key: cord-0042176-j89djkgx
authors: Baker, Katherine H.; Troy, Marleen A.; Herson, Diane S.
title: Detection and Occurrence of Indicator Organisms and Pathogens
date: 2001-10-01
journal: Water Environ Res
DOI: 10.2175/106143000x138373
sha: 61d42b43d3817797ec17625682b0bde8b9726825
doc_id: 42176
cord_uid: j89djkgx

nan

The prevention of infectious diseases transmitted by contaminated water was one of the primary motivations for the development of modern water and wastewater treatment. While current methods to monitor and treat water and wastewater have resulted in dramatic declines in the incidence of such waterborne diseases as cholera and typhoid fever, the organisms causing these diseases still pose a major threat to human health and well-being. Globally, diarrheal diseases, usually transmitted by contaminated food or water, are among the leading causes of infant and child mortality. In addition, emerging waterborne diseases, such as cryptosporidiosis, have emphasized the importance of providing microbiologically safe water to the consumer. In this paper, we review recent information on both indicator organisms and pathogens in the water environment. The focus of this review is on the detection and occurrence of these organisms.

Studies concerning such topics as the design and evaluation of treatment processes, including disinfection, are included only if they relate directly to the detection and occurrence of indicator organisms and pathogens.

recommendation that E. coli should be the principal microbial indicator for potability of untreated waters.

In a review of the prevention and treatment of traveler's diarrhea intended primarily for physicians, Juckett (1999) , emphasized that improvement of sanitary engineering and the development of safe water supplies are more important in the control of these diseases than medical interventions such as prophylaxis or antibiotic therapy. A novel water quality intervention strategy consisting of point-of-use water disinfection, safe storage and community education was field tested in Bolivia (Quick et al., 1999) . Implementation of this intervention strategy resulted in 44% fewer diarrhea episodes in those households using the strategy than in control.

Of particular concern in the control of waterborne diseases are small private water supplies and similar sources of water not receiving adequate treatment. Reacher et al. (1999) reported on an outbreak of gastroenteritis in a village of 700 residents traced to a private water supply and argued that the regulatory framework for such supplies should be modified to ensure safer design and operation. Investigators from the Centers for Disease Control and Prevention (1999) summarized the outbreak of E. coli O157: H7 and Campylobacter jejuni that occurred in September 1999 at the New York State Fair. Contaminated well water was implicated as the source for this outbreak. Based on the results of a survey of the microbiological quality of investigated the relationship between agricultural land-use within a small upland catchment in north Derbyshire, England and concentrations of indicator organisms (fecal coliforms and fecal streptococci). During its passage through the catchment, the stream became significantly contaminated by fecal bacteria, suggesting the existence of a semipermanent store of fecal bacteria in catchment soils, combined with hydrological transport mechanisms capable of moving bacteria from the land to the stream channel. A clear and consistent relationship between the bacterial quality of catchment waters and the intensity of adjacent agricultural land-use was not apparent indicating that multiple factors control the concentration of indicator organisms. Brion and Lingireddy (1999) used fecal bacteria concentrations in water and rainfall data as inputs for training a neural network model to distinguish between urban and agricultural fecal contamination present in inputs to a drinking water reservoir. The average concentrations of microorganisms measured were highly variable and analysis of FC/FS ratios was not able to differentiate between urban or agriculturally impacted sites while the use of the neural network model allowed for differentiation of these sites.

A total of 238 E. coli isolates from human sources (HS) and nonhuman sources (NHS) collected from the Apalachicola National Estuarine Research Reserve, from associated sewage treatment plants, and directly from animals were tested for ribotype (RT) profile by Parveen et al.(1999) . HS and NHS isolates showed 41 and 61 RT profiles, respectively. Discriminant analysis of RT profiles proved to be a useful method for identifying HS and NHS fecal pollution potentially facilitating management practices. Patterns of antibiotic resistance in fecal streptococci were analyzed by discriminant and cluster analysis and used to identify sources of fecal pollution in a rural Virginia watershed (Hagedorn et al., 1999) . Comparison of 892 known-source isolates from a test watershed against the database of organisms of known source resulted in an average correct classification rate of 88%. Combining all animal isolates increased correct classification rates to > or = to 95% for separations between animal and human sources. These results demonstrated that antibiotic resistance profiles in fecal streptococci can be used to reliably determine sources of fecal pollution, and water quality improvements can occur when efforts to address the identified sources are made.

There is a growing appreciation for the impact of wildlife on the presence of indicator organisms and pathogens in aquatic ecosystems. To determine the actual fecal coliform concentrations of gulls and geese and their potential to contaminate water supplies, fecal samples from 249 ring-billed gulls and 236 Canada geese in Westchester County, N.Y., were analyzed over a 2-year period (Alderisio and DeLuca, 1999) . Gull feces contained a greater average concentration of fecal coliform bacteria per Gram than goose feces; however, average fecal sample weights of the geese were more than 15 times higher than those of the gulls. Harwood et al. (1999) isolated total and fecal coliforms from the cloaca and feces of the estuarine diamondback terrapin. Escherichia coli was the predominant fecal coliform species isolated, and members of the genus Salmonella were isolated from 2 of 39 terrapins.

Recreational water that is contaminated with fecal material may pose a risk to individuals using the water for swimming, boating and related activities. There are a myriad of factors which can influence the concentration of indicator organisms (and pathogens) in recreational water.

Emuliani et al. (1999) reported a six to ten fold increase in the numbers of E. coli, thermotolerant coliforms and total coliforms in fluvial recreational waters in Argentina following rainstorms than during dry periods. Even under steady-state weather conditions they found significant temporal and spatial variability in bacterial numbers. Cavallo et al. (1999) also noted a seasonal variability in the numbers of indicator organisms at an anthropogenically-impacted site in the Ionian Sea, Italy. Numbers of indicator organisms were highest in the summer and lowest in autumn. The addition of a new biological sewage treatment plant was found to significantly decrease the number of indicator organisms found at two recreational beaches in Morecambe Bay (Obiri-Danso et al. (1999b) . Interestingly, however, the numbers of thermophilic Campylobacters remained unchanged indicating a source for these pathogens other than wastewater contamination. Smith et al. (1999) demonstrated the importance of consideration of wind speed and direction in the proper monitoring of indicator bacteria in an area where sewage was discharged into the sea near the mouth of a river. They reported that the numbers of E. coli found in a sample were significantly higher at downwind sites than at upwind sites and argued that the failure to account for wind speed and direction could call the validity of many monitoring programs into question.

In addition to direct transmission of diseases via ingestion of contaminated water, water can also serve as an indirect source of microorganisms by contaminating foods prepared in the water. Rampersad et al. (1999) found the water used in the preparation of raw oysters in Western Trinidad was a significant source of contamination with both indicator organisms and pathogens (Salmonella). Rhodes and Kator (1999) reported that human-specific bifidobacteria correlated with identifiable human sanitary deficiencies in feeder streams to estuarine creeks in two of three watersheds examined, one rural and one moderately developed. Recovery of sorbitol-fermenting bifidobacteria, however, was complicated by high background levels of Gram-positive rods and cocci and although human specific bifidobacteria hold promise as indicators of diffuse fecal contamination, methodological constraints limit application to situations of gross contamination.

Widespread use of antibiotics has lead to the proliferation of antibiotic resistant strains of bacteria. When the incidence of resistance to a number of antibiotics (ampicillin, chloramphenicol, kanamycin, naladixic acid, neomycin, and streptomycin) in native heterotrophic bacteria and E. coli isolates along a range of sites on the Yarra River in southeastern Australia was examined, E. coli from rural sites were found to have a lower incidence of resistance than isolates from urban sites (Boon and Cattanach, 1999) . This may indicate that antibiotic resistance can be used as an indicator of bacteriological water quality. Wiggins et al. (1999) conducted a study to determine the reliability and repeatability of antibiotic resistance analysis as a method of identifying the sources of fecal pollution in surface water and groundwater. Four large sets of isolates of fecal streptococci (from 2,635 to 5,990 isolates per set) were obtained from 236 samples of human sewage and septage, cattle and poultry feces, and pristine waters. Their data indicated that there are measurable and consistent differences in the antibiotic resistance patterns of fecal streptococci isolated from various sources of fecal pollution and that antibiotic resistance analysis can be used to classify and identify these sources.

The presence of fecal sterols such as 4-desmethyl sterols and n-alkanols has been used as a biomarker for fecal contamination. Fernandes et al. (1999) used fecal sterols to evaluate the sources of organic matter in a eutrophic urban estuary. Using these compounds as markers, they were able to demonstrate the o of sewage input into the system. in situ survival experiments performed in river water, whereas the numbers of phages decreased between 1 and 2 log units. Chlorination and pasteurization treatments that reduced the numbers of bacteria by approximately 4 log units reduced the numbers of bacteriophages by less than 1 log unit. Sata et al. (1999) examined the influence of starvation on the culturability of E. coli O157:H7 in selective and nonselective media. Their results indicated that the isolation of staved cells would be extremely difficult with direct culture on selective media and recommended the inclusion of a resuscitation step in non-selective media to improve recovery of the organism from water samples. Rajiowski et al. (1999) also found improved recovery of VTEC from spiked samples of reconditioned wastewater from a pork-processing plant when the samples were plated onto non-selective rather than selective media. Pyle et al. (1999) described a rapid direct method to enumerate active E. coli O157:H7 in food and water samples. The method which combines immunomagnetic separation to concentrate the cells with specific fluorescent antibody staining and activity determination using cyanoditolyl tetrazolium chloride reduction allowed for the direct microscopic enumeration of the organism. Studies using spiked samples indicated that enumeration using this method was comparable to enumeration using cultural methods in a significantly shorter period of time (5-7 h.). Kurokawa et al. (1999) compared direct in situ PCR with HNPP/Fast Red TR to direct fluorescent antibody staining for the detection of VTEC in river water. Their results indicated that the two methods gave similar counts of organisms and therefore concluded that direct in situ PCR is a useful tool for detecting cells carrying specific genes in natural environments.

Water obtained from a shallow well was implicated as the source of an outbreak of E. coli O157:H7 among tourists visiting the Canary Islands in March 1997 . While the well water was not used directly for drinking, it was used to wash raw vegetables before consumption. The electrophoretic mobilities (EPMs), an indicator of the transport of organisms in groundwater, of a number of Escherichia coli O157:H7 and wild-type E. coli strains were measured (Lytle et al., 1999b) . The effects of pH and ionic strength on the EPMs were investigated. The EPMs of E. coli O157:H7 strains differed from those of wild-type strains. As the suspension pH decreased, the EPMs of both types of strains increased. Paunio et al. (1999) presented an epidemiological analysis of an outbreak of E. coli O157:H7 in Finland in 1997. Infected individuals were found to have been significantly more likely to have swum in a shallow beach than matched uninfected controls implicating lake water as a vehicle of E. coli O157:H7 transmission. Livestock such a cattle are frequent carriers of E. coli O157:H7 and contamination of surface water with feces from livestock can result in the presence of these organisms in recreational and drinking water. Michel et al. (1999) examined the temporal and spatial distribution of 3001 cases of verocytotoxigenic (VTEC) E. coli occurring in Ontario, Canada. They found that cattle density had a positive and significant association with VTEC incidence of reported cases. Rice et al. (1999) determined the sensitivity to chlorination of isolates of E. coli O157:H7 from waterborne outbreaks. Chlorine levels typically maintained in water systems were found to be sufficient to inactivate these organisms. Holler et al. (1999) reported on the isolation of enterohaemorrhagic E. coli from municipal sewage indicating that contamination of either drinking or recreational water with improperly treated sewage could pose a health risk. responsible for human infections belonging to subspecies 1. Salmonella can be differentiated into over 2000 serotypes. In recent years taxonomists have suggested several different nomenclatures for Salmonella, but because of their complexity none has been generally accepted. Ingestion of Salmonella usually leads to one of three possible manifestations -gastroenteritis, systemic infection or an asymptomatic carrier state -with gastroenteritis being the most common outcome.

Salmonella are associated with fecal pollution, and may be found in any water source subject to such contamination. Rajkowski and Dudley (1999) compared the recovery of Salmonella sp. and Vibrio sp. grown under nutrient limited conditions using nonselective and pathogen-specific selective media. For both of these organisms, spiked into filter-sterilized reconditioned wastewater, recovery was significantly higher using non-selective media than on selective media. The authors concluded that the presence of stressed or injured cells in low-nutrient conditions such as water samples could result in underestimation of the number of these pathogens present. Waage et al. (1999b) developed a PCR assay with two nested pairs of primers selected from a DNA fragment from the Salmonella typhimurium chromosome. When this assay was used to evaluate spiked water samples after overnight enrichment in non-selective media, detection levels as low as 10 CFU per 100 ml were found even in the presence of 8700 heterotrophic organisms and 1000 coliforms per 100 ml sample. A comparative evaluation between the ISO method and one based on polymerase chain reaction (PCR), the PROBELIA, for the detection of Salmonella in water was performed (Coquard et al., 1999) . Waters from different origins were tested either directly or after artificial contamination with selected Salmonella strains isolated from the environment. The results clearly demonstrated that the PCR-based method can advantageously replace the ISO 6340 method. It is quicker, less labor intensive, reproducible, and provides results that match those obtained by the ISO method.

The incidence of serotypes of Salmonella in three types of environmental water (sea, river and fresh) from north-east Spain was investigated over a period of five years (1992) (1993) (1994) (1995) (1996) (Polo et al., 1999) . A total of 823 strains were isolated and 55 different serotypes were identified, 42 were recovered from sea water, 32 from river water and 12 from fresh water reservoirs.

Significant differences were assessed in the indicator organism densities between the samples with serotypes of clinical significance (S. enteritidis, S. infantis, S. typhimurium, S. virchow and S. paratyphi B) and those without clinical significance. Krampitz et al. (1999) examined the survival of Salmonella enteritidis, Yersinia enterocolitica, and Campylobacter Jejuni in artificially contaminated cistern-collected rain water. While both Salmonella and Yersinia were able to persist longer than Campylobacter, none of the organisms was able to grow under the temperatures examined (5 to 37 o C) even in the presence of supplemental organic matter. Tarr et al. (1999) reported on the ongoing epidemic of typhoid fever in Tajikistan that started in 1996 involving more than 24,000 cases, and characterized by multiple point sources, overflow of sewage, contaminated municipal water, and person-to-person spread. More than 90% of the Salmonella typhi isolates were multidrug-resistant (MDR) including the first reported isolates resistant to ciprofloxacin. The authors argued that mass immunization may be a useful measure for the control of prolonged MDR typhoid fever epidemics, as an adjunct to correction of municipal infrastructure and public health intervention. Aiat Melloul and Hassani (1999) concluded that the use of untreated wastewater caused an excess of Salmonella infection among children living in El Azzouzia (the wastewater-spreading area of Marrakesh city, Morocco) compared with those from a control area that does not practice sewage irrigation (Sidi Moussa).

The prevalence of infection in the exposed group (32.56%) was significantly (P < 0. 001) higher than for the control group (1.14%). Crop irrigation with untreated wastewater caused a significantly higher rate of infection with Salmonella in the children of agricultural workers (39.33%) than in the children of non-agriculturists (24.58%). A retrospective study of the Salmonella sp. strains and human salmonellosis episodes registered in the Public Health Laboratory of the Principado de Asturias, Spain, over the seven year period (1990) (1991) (1992) (1993) (1994) (1995) (1996) documented the presence of 45 serotypes among the isolates with Enteritidis, Typhimurium, Virchow, and Hadar being the serotypes most frequently isolated (Gonzalez-Hevia et al., 1999) . Murakami et al. (1999) examined the genetic diversity of Salmonella choleraesuis subspecies choleraesuis serovar Infantis focusing on whether environmental isolates were similar or identical to human isolates. While the isolates showed 35 distinct pulsed-field profiles, none had the genotype of the human isolates. These results indicated that relatively fewer clonal lines of S.

serovar Infantis had spread widely.

Vibrio spp. are Gram negative, rod-shaped, motile bacteria, which show a curvature when examined under optimum conditions. There are a large number of species now described in this genus. In relation to public health, the important species are V. cholerae, V. parahaemolyticus and V. vulnificus. Other vibrios, which are usually regarded as non-pathogens, are common in the coastal environment, e.g. V. alginolyticus and V. metschnikovii.

The most important human disease caused by vibrios is cholera, a disease that is characterized by acute diarrhea and dehydration. Historically there have been cholera pandemics, which have been documented, from 1817. Until 1991 these were caused by the O1 serotype of V.

cholerae which produces a cholera toxin. In 1991 a new serotype, O139 was identified as causing cholera in South Asia with epidemic potential. Other serotypes of V. cholerae can also cause gastroenteritis by toxin production or other enteropathogenic mechanisms. V. parahaemolyticus can cause gastroenteritis frequently associated with under-prepared seafood in areas with warm sea water. Infection of wounds with V. vulnificus may result from contact with contaminated sea water. Some other vibrios have been associated with gastroenteritis (e.g. V. fluvialis and V. mimicus) or localized superficial infections (e.g. V. alginolyticus). Shapiro et al. (1999) performed a case-control study among 61 cholera patients and matched controls in Nyanza Province in western Kenya. Multivariate analysis showed that risk factors for cholera were drinking water from Lake Victoria or from a stream, sharing food with a person with watery diarrhea, and attending funeral feasts. Compared with other diarrheal pathogens, cholera was more common among persons living in a village bordering Lake Victoria.

The occurrence, diversity, and pathogenicity of Vibrio spp. were investigated in two estuaries along the Italian Adriatic coast (Barbieri et al., 1999) . Vibrio alginolyticus was the predominant species, followed by Vibrio parahaemolyticus, non-O1 Vibrio cholerae, and Vibrio vulnificus indicating a significant presence of potentially pathogenic Vibrio strains along the Adriatic coast.

Zooplankton and phytoplankton have been considered as possible reservoirs for Vibrio cholerae in estuarine and brackish waters. Islam et al. (1999) examined the possible role of a cyanobacterium, Anabaena sp., as a reservoir of V. cholerae O1 using culture, PCR, and immunoelectron microscopy. Culturable V. cholerae were detected for up to 1 hour in association with Anabaena sp. ;however, viable but nonculturable (VBNC) V. cholerae O1 were detected for up to 25 months using PCR and immunoelectron microscopy. The authors concluded that VBNC V. cholerae can multiply and maintain their progeny in the mucilaginous sheath of Anabaena sp. Biofilms are known to serve a protective role in microbial communities. Yildiz and Schoolnik (1999) examined the genetics of exopolysaccharide production in the rugose colony variant of Vibrio cholerae O1, biotype El Tor, They note that the biofilm-forming properties of exopolysaccharide production may enable the survival of V. cholerae O1 within aquatic habitats between outbreaks of human disease. Watnick and Kolter (1999) reported that, in a simple, static culture system, wild-type Vibrio cholerae El Tor forms a three-dimensional biofilm with characteristic water channels and pillars of bacteria.

The emergence of Vibrio cholerae O139 in 1992 and reports of an increasing number of other non-O1 serogroups being associated with diarrhea, stimulated Dalsgaard et al. (1999) Arias et al. (1999) evaluated the occurrence of Vibrio vulnificus in natural marine samples from the Spanish Mediterranean Sea using nested PCR and cultural approaches using thiosulphate-citrate-bile salts-sucrose agar (TCBS) and cellobiose-polymixin B-colistin agar (CPC), incubated at 40 o C, as selective media. They isolated the organism from sea water and edible bivalves. The incidence of this species in the samples studied was lower than that described for other geographical areas, probably due to the high salinity values of the Mediterranean Sea. The occurrence of Vibrio vulnificus in coastal sea water and sand was investigated by Ghinsberg et al. (1999) . V. vulnificus isolates were recovered from both sea water and sand. V. vulnificus was more frequently isolated during July, August and September. The relatively high isolation rate of this bacterium from sea water may be dangerous to bathers, fishermen, and divers with predisposed wounds. Marino et al. (1999) evaluated the accumulation and depuration of microorganisms in mussels maintained in static seawater, contaminated with 10 4 to 10 6 cells/ml. E. coli and S. typhi accumulated to a greater extent and were released from mussels more quickly than vibrios. Zanetti et al. (1999) investigated the usefulness of a PCR fingerprinting technique to differentiate 30 Vibrio alginolyticus strains isolated in Sardinian waters. The results were then compared with the patterns obtained by ribotyping. PCR fingerprinting could differentiate the strains analyzed into 12 different patterns, whereas ribotyping generated only 7 different profiles.

The study revealed the superior discriminative power of the PCR for the differentiation of related V. alginolyticus strains and its potential use in epidemiological studies.

Culture of Campylobacter from environmental samples typically involves the use of selective media containing antibiotics. Manson et al. (1999) demonstrated that such techniques failed to detect sublethally injured cells from water samples; however initial enrichment in broth without antibiotics for four hours followed by the addition of antibiotics significantly increased recovery of Campylobacter from water. Cappelier et al. (1999) were able to recover cells of Campylobacter from a VBNC state (starvation in surface water for 30 days) by inoculating the cells into the yolk sacs of embryonated eggs even though direct plating onto solid media failed to detect the cells. Waage et al. (1999c) developed a rapid and sensitive semi-nested PCR assay for detection of small numbers of Campylobacter jejuni and Campylobacter coli cells in environmental water, sewage, and food samples. The assay allowed for the detection of 3 to 15 CFU of C. jejuni per 100 ml in water samples containing a background flora consisting of up to 8700 heterotrophic organisms per ml and 10000 CFU of coliform bacteria per 100 ml. Merritt et al. (1999) investigated an outbreak of Campylobacter enteritis among staff on a resort island in north Queensland. Although Campylobacter sp. were not isolated from any environmental samples, fecal contamination was detected in four rainwater tanks. In addition, there was a strong association between gastrointestinal illness and consumption of water from a dispenser in the staff restaurant that had probably been filled from one of the contaminated tanks.

The authors concluded that the outbreak was probably a waterborne outbreak and postulated that Campylobacter species were introduced into one or more of the tanks by contamination with the feces of wild animals. Hudson et al. (1999) analyzed 180 Campylobacter isolates from human and veterinary cases, raw milk and chicken, and untreated water. Isolates were typed by Penner serotyping and pulsed-field gel electrophoresis (PFGE) of restriction enzyme-produced DNA fragments.

Seasonal differences between the isolate were used in serotyping. In contrast, one PFGE restriction profile type was dominant regardless of season. Some isolates from human cases were indistinguishable from others isolated from water and raw chicken, indicating possible routes of infection for humans. Campylobacter spp. were isolated from 50% of samples from non-EEC standard beaches and 40% from EEC standard beaches in a study by Bolton et al. (1999) . The prevalence of Campylobacter spp. was greater in wet sand from both types of beaches but, surprisingly, more than 30% of samples from dry sand also contained these organisms. The major pathogenic species C. jejuni and C. coli were more prevalent in sand from non-EEC standard beaches indicating that Campylobacter strains associated with human infections are frequently found in sand on bathing beaches. Obiri-Danso and Jones (1999a) monitored two freshwater bathing sites, on the River Lune in the north-west of England over a 2 year period for fecal indicators, fecal coliforms and fecal streptococci, as well as, Salmonella and Campylobacter, to determine compliance with the EU Directive on Bathing Water Quality. Fecal indicator numbers showed no seasonal variation, with numbers in the bathing season similar to those in the nonbathing season. Fecal indicator numbers in the sediments were an order of magnitude higher than in the overlying water. Campylobacter numbers showed seasonal variation in the water with higher counts in winter than in the summer, although numbers were low. Higher numbers were found in the sediments but there was no seasonal variation. Analysis of various inputs showed that indicators and Campylobacters came from a mixture of sources, namely a sewage treatment works, agricultural run-off, streams and mallards. Thomas et al. (1999) Campylobacter coli and C. upsaliensis demonstrated comparable survival characteristics but were less resilient than C. jejuni and C. lari. The authors concluded that C. jejuni and C. lari are most likely to be the causative agents in water-mediated Campylobacteriosis.

Initially classified as aerotolerant members of the Campylobacters, Arcobacter was recently recognized as an independent genus of bacteria. Members of the genus Arcobacter are Gram-negative, non-sporeforming rods. The cells are usually curved or S-shaped, and are motile with a darting, corkscrew-like motion by means of a single polar, unsheathed flagellum. Four species of similar general morphology are recognized: Arcobacter cryaerophilus (containing two subgroups, and formerly called Campylobacter cryaerophila), A. butzleri (also formerly C. cryaerophila), A. skirrowii, and A. nitrofigilis (formerly C. nitrofigilis). A. butzleri is the species most commonly associated with illness in humans and has been isolated from stools of patients with abdominal pain and/or diarrheal illness. It is not known how humans become infected by Arcobacters, but consumption of or contact with potentially contaminated water associated with travel has been suggested as a possible pathway. Rice et al. (1999) reported on the isolation of Arcobacter butzleri from a contaminated ground water source. Survival studies with this isolate indicated that it was capable of surviving in the ground water environment. The isolate was found to be sensitive to chlorine. The presence of thermophilic Campylobacters and Arcobacter was investigated in four types of sewage sludge taken from the treatment plant in Bologna (Italy): primary, activated, thickened and anaerobically digested sludge (Stampi et al., 1999) . Arcobacter butzleri were found in all types of sludge. They were less sensitive to anaerobic digestion than fecal bacteria, probably due to their microaerophilic growth properties; therefore, land application of digested sludges may cause high risks of infection.

Helicobacter pylori is a spiral shaped bacterium frequently isolated from the gastric mucosa of humans. In most individuals, the organism appears to be a commensul with no clinical symptoms associated with colonization. In a small percentage of infected individuals, however, significant clinical manifestations including peptic and duodenal ulcers, MALT lymphoma and adenocarcinoma of the stomach develop.

The route of transmission of this organism remains controversial, however, there is growing evidence implicating a waterborne route of transmission. Velazquez and Feirtag (1999) reviewed the phenotypic and genotypic characteristics, methods for culturing, role in gastric pathogenicity, evidence involving its mode of transmission, difficulty in its isolation and detection methodology of Helicobacter pylori. They noted that both foodborne and waterborne pathways have been proposed as the mode of transmission for H. pylori as the patterns of the infection are consistent with those from fecal-oral and oral-oral transmission. Finally, they review current methods for the detection of the organism including filtration, immunoseparation (IMS), polymerase chain reaction (PCR), probe hybridization, immunostaining, autoradiography and ATP bioluminescence. On the other hand, Stone (1999) and Nabwera and Logan (1999) argue against waterborne transmission of H. pylori in favor of direct person-to-person transmission.

In an epidemiological study of H. pylori infection among preschool children in Taiwan, Lin et al. (1999) found a higher incidence of infection in children from aboriginal townships than metropolitan areas. This suggested that a poor water supply system, sewage disposal, and other environmental hygiene in the aboriginal townships might have played some role in infection with H. pylori. Lindkvist et al. (1999) found that children who obtained their drinking water from rivers or pipers were significantly more likely to be infected with H. pylori than children who obtained their drinking water from a well in an epidemiological study in Ethiopia. Lindo et al. (1999) researched epidemiological associations between environmental and demographic factors and prevalence of Helicobacter pylori infection in a suburban Jamaican community. Logistic regression showed that sanitation and the presence of domestic animals were independently associated with H. pylori seropositivity, indicating that a combination of demographic, environmental and zoonotic factors is involved in the spread of H. pylori infections at the tropical community level. In a follow-up to a 1996 epidemiological study, Sasaki et al. (1999) assayed samples of tap and well water, in addition to soils, flies, and cow feces for the presence pylori, by PCR, in local water supplies. The seroprevalence of H. pylori in the study group was higher than rates in southern Canadian populations. The detection of H. pylori in local water supplies may indicate a natural reservoir for the organism or possible contamination from human sewage. In contrast, Bernstein et al. (1999) were unable to detect H. pylori DNA in lake water in an Indian village in Manitoba Canada where the incidence of infection among the residents was high.

Hegarty et al. (1999) used combined fluorescent-antibody-tetrazolium-reduction in a survey of surface water and shallow water for the presence of H. pylori. H. pylori were found in the majority of samples tested supporting a waterborne route of transmission for this organism.

There was no significant correlation between the occurrence of either total coliforms or E. coli in the water and the presence of H. pylori, indicating that routine screening of water supplies for traditional indicator organisms may fail to protect the consumer from exposure to H. pylori. Stark et al. (1999) reported on the production of a water-insoluble biofilm when H. pylori was grown with a high carbon:nitrogen ratio. They suggested that the production of a biofilm might be important in enhancing survival of H. pylori under adverse environmental conditions.

Legionella are small, aerobic, motile rod-shaped bacteria. The respiratory diseases produced by the Legionella genus of bacteria are collectively called Legionellosis. Presently more than 34 species of Legionella have been identified, 20 of which have been isolated from both environmental and clinical sources. The diseases produced by Legionella include the pneumonic form, Legionnaires' disease, and the flu-like form, Pontiac fever Legionella pneumophila is widespread within aquatic environments and can infect humans following the inhalation of aerosols generated by air-conditioners and other devices.

Winiecka-Krusnell and Linder (1999) under adverse environmental conditions such as desiccation, elevated temperatures and the presence of disinfectants as well as the importance of amoebae in the transport of these bacteria.

Kasuga et al. (1999) investigated selective cultivation media and previous treatments of samples suitable for detection of Legionella species from environmental water and for elimination of co-existing microbes, which gave, rise to an interference with the evaluation of Legionella sp. growth. They found that the combined pre-treatment of water samples with acid after heating and the addition of polymyxin-B and oxytetracycline into selective cultivation medium enhanced the detection of Legionella sp. from environmental water. Two different decontamination systems, heat and acid, and two isolation media, GVPC and MWY agar were tested for the recovery of Legionella pneumophila from drinking water (De Luca et al. 1999) .

Heating at 50 o C for 30 minutes was seen to be the best decontamination system. Agar containing vancomycin, polymyxin B, anysomicin and dyes produced the highest isolation percentages and the highest counts. Schultz-Robbecke et al. (1999) compared four methods for the cultural recovery of Legionellae from naturally contaminated water samples. They recommended the use of direct inoculation onto selective solid growth medium for the recovery of Legionellae at concentrations of > or = to 1 CFU/ml. If Legionellae below this concentration are to be detected they recommend filtration of the sample through cellulose nitrate filters with incubation of the filter directly on the medium as the easiest and most sensitive technique. Saint and Ho (1999) developed a PCR test for the specific identification of Legionella longbeachae targeting a sequence unique to both serogroups 1 and 2. PCR testing was demonstrated as a superior method of identification to traditional seroagglutination reactions. Nakadate et al. (1999) reported on 3 patients who were admitted to the same hospital with atypical pneumonia. All 3 patients had elevated antibody titers for Legionella pneumophila serogroup 1, and had visited the same spa prior to the onset of their symptoms. Inspection of the spa resulted in isolation of Legionella pneumophila serogroup 1 from the facility's hot water tanks and outlets. Luttichau et al.(1999) investigated an outbreak of fever typical of Pontiac fever most likely due to a contaminated whirlpool among nine adults and six children visiting a holiday home. Two adult non-users of the whirlpool had no symptoms and no serological evidence of infection. Castellani et al. (1999) reported on a case of Legionnaire's disease in a 67-year-old, male who contracted the disease during a cruise in September 1995 and died 9 days after disembarking. Legionella pneumophila serogroup 1 was isolated from the patient's sputum and the ship's water supply. Samples from the air-conditioning system were negative.

Sixteen warm-water systems of hospitals, spread out over two locations, were examined for the presence of Legionella (Kohler et al.,1999) . Legionella pneumophila was found in fifteen warm water systems, with a distinct pattern of serogroups between the two locations. Legionella of the same serogroups as those isolated from patients were present in each hospital water supply. Visca et al. (1999) While warm water systems are frequently cited as a reservoir for Legionella, Hoebe et al. (1999) investigated two nosocomial cases of Legionnaires' disease in a rehabilitation center in the South of Limburg, the Netherlands. Legionella cultures were made from respiratory patients' specimens, water samples and smears from all mixing taps (used in showers), samples from hot and cold water taps from the infected ward and from the five other wards. The strains were typed by serotyping and polymerase chain reaction. The circulating cold water sometimes warmed up to 40 o C (within the Legionella growth range). Cultures from the hot water supply were negative just like control cultures from five other wards and swabs from showerheads and hoses. The authors concluded that the combination of an elevated cold water temperature caused by heating along a distance by nearby hot water and heating piping and the regular stasis of water during the weekends when the ward was closed, most probably stimulated the multiplication of Legionella in the cold water supply. From July to September 1994, 29 cases of community-acquired Legionnaires' disease were reported in Delaware. Brown et al. (1999) conducted an investigation to identify the source of the outbreak and risk factors for developing Legionella pneumophila serogroup 1 pneumonia. Water samples taken at the hospital, from eight nearby cooling towers, and from four of the patient's homes were cultured for Legionella. Isolates were subtyped using monoclonal antibody analysis and arbitrarily primed polymerase chain reaction. The results of their investigation suggested that the hospital cooling towers were the source of the community outbreak.

Gregerson et al. (1999) investigated a disease outbreak with fever and flu-like symptoms in wastewater treatment plant workers after repairing a decanter for sludge concentration. The work took place over a period of 10 days in a small closed room, while another decanter was in operation and was consequently emitting aerosol to the environment, to which the workers were exposed. The clinical picture agreed with that described for Pontiac fever, and positive antibody titers to L. pneumophila serogroup 1 were found in blood from all 5 patients. L. pneumophila serogroup 1 was cultured in high amounts from sludge from the decanter. Lawrence et al. (1999) used arbitrarily primed PCR with three primers and pulsed-field gel electrophoresis to characterize a set of 75 clinical Legionella pneumophila serogroup 1 isolates, with no apparent epidemiological link, obtained from 24 hospitals in Paris, France, from 1987 to 1997.

Unexpectedly, 25 clinical isolates from 15 hospitals had an identical profile (termed type A) by both methods. The same profile was subsequently found in 16 of 64 randomly selected environmental L. pneumophila serogroup 1 isolates suggesting that a particular type of L.

pneumophila serogroup 1 is specifically present in the Paris water distribution network. Although about 25% of municipalities in the USA use monochloramine for disinfection of drinking water, the effect of monochloramine on the occurrence of Legionnaires' disease has never been studied. Kool, Carpenter and Fields (1999) used a case-control study to compare disinfection methods for drinking water supplied to 32 hospitals that had had outbreaks of Legionnaires' disease with the disinfection method for water supplied to 48 control-hospitals, with control for selected hospital characteristics and water treatment factors. Hospitals supplied with drinking water containing free chlorine as a residual disinfectant were more likely to have a reported outbreak of Legionnaires' disease than those that used water with monochloramine as a residual disinfectant suggesting that many of outbreaks associated with drinking water might not have occurred if monochloramine had been used instead of free chlorine for residual disinfection.

Members of the genus Mycobacterium are relatively slow-growing, aerobic, rod-shaped bacteria. They contain unique waxy components, mycolic acids, within their cell walls that make them difficult to stain with Gram procedure. While the tuberculosis mycobacteria (M. Dailloux et al .(1999) reviewed the ecology and public health significance of the nontuberculosis mycobacteria (NTM). They stressed the difficulties in isolating these organisms from natural habitats and the importance of water as a route of transmission for these organisms. Iivanainen et al. (1999) studied the occurrence of mycobacteria in aerobic brook sediments from 39 drainage areas in Finland. The culturable counts of mycobacteria were related to climatic conditions, characteristics of the drainage area, chemical characteristics of the sediment and water, culturable counts of other heterotrophic bacteria, and microbial respiration rate in the sediment. The occurrence of nontuberculosis mycobacteria (NTM) was examined in drinking water, bottled water, and ice samples (Covert et al., 1999) . A total of 139 samples were examined for NTM by a membrane filtration culture technique followed by PCR amplification and 16S rRNA sequence determination to identify the isolates. NTM were not detected in bottled water or cisterns but were detected in 54% of the ice samples and 35% of the public drinkingwater samples from 21 states. The most frequently occurring isolate was M. mucogenicum.

Aronson et al. (1999) Hillebrand-Haverkort et al. (1999) isolates (Kauppinen et al., 1999) .

Based on the results of a survey in an area in Indonesia where leprosy was highly endemic, Matsuko et al. (1999) proposed that environmental sources could be involved in the transmission of this disease. They analyzed water sources used daily by the villagers for the presence of M. leprae DNA using PCR. Out of 44 water sources evaluated, 21 were positive for the presence of M. leprae DNA and the prevalence of leprosy among individuals using this water for bathing and washing, but not for drinking was significantly increased. Waage et al. (1999a) developed a nested PCR procedure for the detection of low numbers of Y. enterocolitica in spiked samples from natural surface sources with variable background flora ranging from oligotrophic water to sewage. Their procedure enabled the detection of 8-17 cfu 100 ml-1 water with background levels of up to 8700 heterotrophic organisms ml-1 and 10,000 cfu coliform organisms 100 ml-1 water. The analysis can be completed within 2-3 days. 

Bacterial viruses are known as bacteriophages. Almost every species of bacteria has been reported to host at least one bacteriophage. Bacteriophages serve as important tools for the study of microbial disinfection and biocontrol, viral fate and transport, and indicators of microbial contamination of water sources. Mignotte et al. (1999) compared eight virus extraction techniques on three types of residual urban sludge for simultaneous detection of infectious enteroviruses, somatic coliphages, F-specific RNA bacteriophages and Bacteroides fragilis bacteriophages. Dmitrieva et al. (1999) reported on an accelerated method for detecting coliphages in drinking water. Puig et al. (1999) examined the capability of six strains of Bacteroides fragilis to detect phages in a variety of feces and wastewaters in the area of Barcelona, Spain. One strain (RYC2056) recovered consistently higher counts than the other strains. This strain detected bacteriophages in animal feces even though their relative concentration with respect to other fecal indicators was significantly lower in wastewater polluted with animal feces than in urban sewage.

Puig and Girones (1999) developed a genomic library of a Bacteroides fragilis bacteriophage. A clone of this phage including the MP2 ORF was identified and sequenced. Muniesa et al. (1999c) found significant differences in the proportions of different morphological types of infectious somatic coliphages when fecally polluted water samples were compared to non-polluted water samples. Lasobras et al. (1999) compared the usefulness of three groups of bacteriophages -somatic coliphages, F-specific coliphages, and Bacteroides fragilis phages -for the sanitary monitoring of wastewater sludges. While they found differences in the survival of the phages between different types of sludges, none of the phages was clearly superior to the others as an indicator organism. Sinton et al. (1999) compared sunlight inactivation rates of somatic coliphages, F-specific RNA bacteriophages (F-RNA phages), and fecal coliforms in seven summer and three winter survival experiments. Their results indicated that F-RNA phages and fecal coliforms are more susceptible than somatic coliphages to longer solar wavelengths, which predominate in seawater and therefore warrant consideration as fecal, and possibly viral, indicators in marine waters. Brion and Silverstein (1999) investigated iodine disinfection of a model bacteriophage, MS2. They observed that in the presence of dissolved organic substances, such as detergents and proteins, the inactivation of MS2 viruses decreased significantly. Of special note, was the observation that in the presence of beef extract proteins, an apparent reversal of MS2 inactivation occurred, which was dubbed rebound by the authors.

They noted that MS2 rebound occurred only when the oxidized iodine residual had been quickly consumed by beef extract proteins in solution. The results of their study supported the hypothesis that iodine causes changes in the charge distribution characteristics of the virus protein coat. Kudva et al. (1999) isolated and tested Eschericia coli O157:H7 antigen-specific bacteriophages to determine their ability to lyse laboratory cultures of Eschericia coli O157:H7.

The authors report that virulent O157 anitgen-specific phages could play a role in the biocontrol of E. coli O157:H7 in animals and fresh food without compromising the viability of other normal flora or food quality. The behavior outside the gut of seeded Eschericia coli O157:H7, naturally occurring E.coli, somatic coliphages, bacteriophages infecting O157:H7, and Shiga toxin 2 (Stx2) encoding bacteriophages was studied by Munisea et al. (1999a) . The objective of their study was to determine if the phages persist more successfully in the environment than their host bacteria. They concluded that Stx2-encoding phages persist longer than their host bacteria in the water environment and are more resistant that their host bacteria to chlorination and heat treatment. Schmidt et al. (1999) investigated the ability of a detoxified derivative of Shiga toxin 2 (Stx2)-encoding bacteriophage to infect and lysogenize enteric Eschericia coli strains and to develop infectious progeny from such lysogenized strains. The results of their study demonstrated that phage Φ3538(∆stx 2 ::cat) was able to infect and lysogenize particular enteric strains of pathogenic and nonpathogenic E. coli and that the lysogens produced infectious phage progeny. Stx-encoding bacteriophages are able to spread stx genes among enteric E. coli strains. Hertwig et al. (1999) studied phage-mediated gene transfer in Yersinia enterocolitica by investigating the ability of Yersinia phages to transduce naturally occurring plasmids. The transduction experiments were performed with a temperate phage isolated from a pathogenic Yersinia enterocolitica strain and phage mixtures isolated from sewage. Transductants obtained by infections with the temperate phage were lysogenic and harbored phage genome in their chromosomes.

Shaffer et al. (1999) characterized Pseudomonas aeruginosa bacteriophage UNL-1, a bacterial virus with a novel UV-A-inducible DNA damage reaction phenotype. Their report is the first description of a recA-independent, UV-inducible virus DNA damage repair system.

Their findings suggest that a combination of both host and virus DNA repair processes contribute to the persistence and sustained replication of some bacterial viruses in aquatic environments. Muniesa et al. (1999b) found that the ratios between numbers of bacterial indicators and the numbers of bacteriophages are much higher in feces of seagulls than in treated or raw sewage contributed by out-falls from the northern coastal area of Catalonia (North-eastern Spain). Muniesa et al. (1999c) determined the proportions of different morphological types of infectious somatic coliphages in fecally polluted freshwaters. Nasser and Oman (1999) Bacteriophages have been widely used as surrogates for human enteric viruses in many studies on virus transport and fate. Thompson and Yates (1999) investigated the fates of three bacteriophages, MS2, R17 and phiX174 in a series of batch dynamic systems. Their data suggested that viral inactivation in simple dynamic batch experiments is dependent upon (i) the presence of a dynamic air-water-solid interface (where the solid is a hydrophobic surface), (ii) the ionic strength of this solution, (iii) the concentration of surface active compounds in the solution, and (iv) the type of virus used. Deborde et al. (1999) studied the rapid transport of viruses in an unconfined floodplain aquifer near Missoula, MT, which was instrumented with 89 monitoring wells and 20 four-port multilevel samplers. Bromide, bacteriophages MS2, PRD1 and ΦX174 and the attenuated enterovirus poliovirus (type-1 CHAT) strain were seeded into the aquifer as slug injections. The authors observed that although relative attenuations at downgradient monitoring wells indicated that the virus tracers were attaching to aquifer material along the groundwater flowpath, the virus peaks arrived at observation wells at rates similar to that which was observed for the bromide tracer. Deborde et al. (1999) indicated that natural attenuation of a slug virus input over a "typical" source supply-set-back distance of 30.5m would most likely not reduce virus concentrations to proposed acceptable risk levels in similar cold-water high-velocity groundwater systems. Yanko et al. (1999) tested potable and monitoring wells located in close proximity to a large groundwater recharge project which utilizes a blend of surface water and reclaimed wastewater for recharge. The authors analyzed for coliphage over a six-month period to assess the potential for virus migration. The concentration and distribution of phage isolated was found to be quite different in chlorinated effluent compared to river water. The majority of isolates from reclaimed water were filamentous DNA F-specific phage suggesting that this group was more resistant to chlorine. Groundwater samples were analyzed using a novel large volume enrichment technique that proved very sensitive for determining low concentrations of phage. Chauret et al. (1999) assessed the extent of reduction in selected microorganisms during both aerobic wastewater treatment and anaerobic digestion of sludge at an Ottawa, Ontario, Canada wastewater treatment. The fate of two encysted pathogenic protozoa was compared with that of microbial indicators including somatic coliphages. A reduction in the numbers of somatic coliphages was observed during both aerobic wastewater treatment and anaerobic sludge digestion. Lasobras et al. (1999) studied the recovery of three groups of bacteriophages, somatic coliphages, Bacteroides fragilis phages and F-specific bacteriophages from the primary sludge of a biological treatment plant, a lime-treated sludge and in a de-watered anaerobically, mesophilically-digested sludge. All phages studied accumulated in the sludges. In primary and activated sludges, all three types accumulated similarly, but in lime-treated sludge and dewatered, anaerobically, mesophilically-digested sludge, the relative proportion of F-specific bacteriophages decreased significantly with respect to somatic coliphages and bacteriophages infecting B. fragilis. All phages survived successfully in stored sludge, depending on the temperature. F-specific bacteriophages survived less successfully than the others.

An evaluation to determine possible indicators of viral aerosol contamination in sewage treatment plants was conducted in a yearlong study by Carducci et al. (1999) . The objective of their study was to evaluate the relationships between the presence of cytopathogenic viruses and the counts of total bacteria, fecal streptococci and somatic coliphages in samples collected at various distances from an aeration tank at an activated sludge plant. The authors report that when the virus was found to be present in sewage, it was also in the air at the sites sampled closest to the aeration tank. Total bacteria and fecal streptococci counts were generally positively correlated with viral presence, while coliphage counts yielded no analogous relationship.

Infections with viral hepatitis are currently attributed to five known agents, hepatitis A, hepatitis B, hepatitis C, hepatitis D and hepatitis E. The primary target for all five of the known hepatitis viruses in humans is the liver. Currently, waterborne disease transmission is most frequently associated with hepatitis A virus (HAV), hepatitis E virus (HEV) and potentially forms of non-A and non-B hepatitis virus.

Winn (1999) reviewed enterically-transmitted hepatitis, which is caused by hepatitis A virus and hepatitis E virus. Both agents are transmitted via contaminated water, often through food vehicles. Lerman et al. (1999) conducted a study to identify occupations at risk for hepatitis A infection and to determine their relative risk. Their study entailed determining the relative risk of hepatitis A among different occupations in Israel according to the incidence of hepatitis A in different occupations during 1993 and 1994 compared with the incidence of hepatitis A in two standard populations. After, age, gender, ethnicity, and time of immigration to Israel were controlled for, certain occupations showed a significant increased risk of hepatitis A: yeshiva students, day care center and kindergarten staff, food industry workers, teachers, physicians and dentists and therapists and medical technicians. Sewage workers and nurses did not show any significantly increased risk.

De Serres et al. (1999) found that an outbreak of hepatitis A virus in a rural river-island community was associated with the consumption of contaminated well water. Immunocapture reverse-transcription polymerase chain reaction was used to assess specimens from case-patients, the implicated well and a cesspool suspected to be the source of contamination. All were positive for HAV RNA. HAV RNA was also detected in the contamination source six months after the initial contamination, when fecal coliform bacteria were no longer present. Their findings demonstrated the utility of viral detection techniques to evaluate contaminated ground

water. An initial retrospective study conducted by Leach et al. (1999) demonstrated a high prevalence of hepatitis A but not hepatitis B or C infection among children living along the Texas-Mexico border. Independent risk factors for hepatitis A infection included increased age, residence, and history of residence in a developing country. Use of bottled water (vs. municipal or spring/well water) and years of maternal secondary education were found to be protective.

The authors report that improved sanitation or routine hepatitis A vaccination in early childhood may reduce the prevalence of hepatitis A in these areas. To assess the impact of water sanitation and sewage disposal as part of a major environmental control program in Rio de Janeiro, Brazil, Struchiner et al. (1999) carried out sero-prevalence studies for hepatitis A virus in three microregions which varied with regard to level of sanitation. The results of their study supported the choice of HAV as a sentinel disease that is associated with level of sanitation.

A study performed by Lee et al. (1999) suggested that direct examination of hepatitis A virus in shellfish indicated that it might be useful for monitoring HAV in the water environment.

An internal standard RNA with a 7-nucleotide deletion for competitive reverse transcription RT-PCR was used by Arnal et al. (1999) to quantify hepatitis A virus in experimentally contaminated mussels. A method for the detection of hepatitis A virus in shellfish by nested reverse transcription-PCR was presented by Croci et al. (1999) . They report that the use of nested PCR rendered the system more sensitive and specific.

The unique riverine ecology of hepatitis E virus transmission in South-East Asia was assessed by Corwin et al. (1999) from a review of reports of hepatitis outbreak investigations, cross-sectional prevalence studies, and hospital-based case-control studies. They report that findings from Indonesia and Viet Nam showed epidemic foci centered in jungle, riverine environments, few cases of acute, clinical hepatitis from cities in Indonesia, Viet Nam and Laos could be attributed to HEV. Uses of river water for drinking and cooking, personal washing, and human excreta disposal were all significantly associated with high prevalence of infection.

Boiling of river water was shown to have protective value in preventing HEV transmission. Martinson et al. (1999) studied hepatitis E virus (HEV) seroprevalence in children living in rural Ghana in a rural district with very little pipe-borne water supply. The authors state that large outbreaks of hepatitis E virus have been reported in warm climates with poor sanitation, although it has also been reported to exist in endemic form in these areas. Divizia et al. (1999b) studied the a total of 202 serum and stool samples form acute hepatitis patients admitted to the Fever Hospital of Alexandria, Egypt to reveal markers of hepatitis A virus and hepatitis E virus infection. Their data confirmed that HAV and HEV are common causes of acute sporadic hepatitis in Alexandria, but with different peak age positivity.

Dual infections (HAV-HEV and HEV-enteric viruses) were also reported. Hau et al. (1999) conducted a study in southwestern Vietnam in an area adjacent to a known focus of epidemic hepatitis E virus for antibody prevalence for hepatitis A virus and hepatitis E. The objective of their investigation was first to provide a prevalence measure of hepatitis infections, and second to determine the outbreak potential of HEV as a function of the susceptible population. Boiling of water was found to be protective measure against HEV transmission. A relatively low prevalence of anti-HEV indicated considerable HEV outbreak potential against a background of 1) poor, water, related hygiene/sanitation, 2) dependence on a (likely human/animal waste)-contaminated Mekong riverine system, and 3) periodic river flooding. Brautbar and Navizadeh (1999) reported that sewage workers may be at increased risk of contacting hepatitis C. Their findings were based on the specific occupational history of two patients as well as an epidemiological literature review where sewer-contaminated water is described as a known vector for outbreaks of hepatitis C.

Members of the genus Enterovirus, of the family Picornaviridae, that are know to infect humans include poliovirus, coxsackieviruses of the A and B groups, echoviruses, and enteroviruses that have been given sequential numbers. Enteroviruses are also increasingly being used as indicators of fecal contamination because they can be easily assayed for in the laboratory and have been found to endure in aquatic environments.

Polymerase chain reaction has been utilized in several studies for the detection of viruses in environmental samples. Abbaszadegan et al. (1999) evaluated the use of PCR for detection of enteric viruses in groundwater in 150 samples. Viruses were detected after concentration from at least 400 gallons of water (1,512 liters). Their results indicated that PCR seems to be a desirable rapid initial screening tool for viruses in water. Green and Lewis (1999) examined the utility of reverse transcription-PCR (RT-PCR) assays for monitoring enteric viruses contaminating wastewaters, sediments and shellfish. Their study was done over a 12-month period from and around a large cosmopolitan sewage treatment facility in Auckland, New Zealand.

Enteroviruses, rotaviruses and hepatitis A virus (HAV) were detected by PCR in different sample types at various time points. The results of this study indicted that RT-PCR was most useful when examining samples for viruses routinely difficult to identify, namely rotaviruses and HAV. Griffin et al. (1999) found that exposure to canal waters in the Florida Keys through recreation and work may be contributing to human health risks. They report that seventy-nine percent of the sites samples were positive for the presence of enteroviruses by reverse transcriptase PCR (poliovirus, coxsackie A and B viruses, and echoviruses). Sixty-three percent of the sites were positive for the presence of hepatitis A viruses. Ten percent of the sites were positive for the presence of Norwalk viruses. Ninety-five percent of the sites were positive for at least one of the virus groups. The results of their study indicate that the canals and nearshore waters throughout the Florida Keys are being impacted by human fecal material carrying enteric viruses through current wastewater treatment techniques such as septic tanks. Gualillo et al. (1999a) describe the identification of enteroviruses in environmental samples using PCR couple with a colorimetric microwell method. Gualillo et al. (1999b) describe a simple method of detecting enteroviruses in contaminated mollusks and sewage by using polymerase chain reaction coupled with colorimetric microwell detection assay. A 5-h, user-friendly PCR assay was used to detect enteroviruses in bivalve mollusks (clams) and sewage. They report that this method has greater advantages over conventional methodologies for routinely screening a large number of samples, specifically, the rapid acquisition of results and cost effectiveness. Pregliasco et al. (1999) describe their experiences on the Ticino River (Italy) searching for enetroviruses in surface waters via RT-PCR. Gantzer et al. (1999) report on a multi-centric study carried out in three laboratories to evaluate the efficiency of a standardized kit (Amplicor) for the detection of enterovirus genome in wastewater. The results of their study indicated that the Amplicor kit is well suited for the detection of enterovirus genome in treated wastewater. Sensitivity of the detection of infectious viruses and virus genome was improved when concentrated samples were used for analysis.

A comparative study was conducted by Bonadonna et al. (1999) to evaluate the potential of peracetic acid and sodium hypochlorite to inactivate bacteria and viruses in sewage effluent.

Under the experimental conditions, no representative results were obtained for enteroviruses and phages because of their low concentrations in the test sample.

Vaccine strains of polioviruses were isolated from surface waters during and shortly after two rounds of mass vaccinations of children in an informal settlement where there was no sewerage.

The results of their study indicated that neither poliovirus vaccine strains nor other viruses were likely to significantly interfere with the detection of wild-type polioviruses. In their study, Grabow et al. (1999a) indicate that optimal isolation of polioviruses was accomplished by parallel inoculation of L120B mouse cells and at least the PLC/PRD/5 human liver and buffalo green monkey (BGM) kidney cell lines. Analysis of cell cultures using the polymerase chain reaction revealed that 319 test samples contained at least 263 human enteroviruses that failed to produce a cytopathogenic effect. This type of analysis was reported to significantly increase the sensitivity of enterovirus detection. Petit et al. (1999) described an extraction procedure for genomic DNA and RNA of viruses (as well as bacteria) from polluted estuary water. They described an example of molecular detection of poliovirus (also Salmonella) in the Seine (France) estuary, and an approach to studying their association with organo-mineral particles. Manor et al. (1999a) utilized a double-selective tissue culture system for isolation of wild-type poliovirus from sewage samples containing vaccine polioviruses and other enteroviruses, with a detection limit of 18 to 50 plaque-forming-units (PFU) per 1 to 2 liters of sewage.

A new adsorbent, active aluminum oxide was evaluated by Amvros'eva et al. (1999) for its concentrating properties towards poliomyelitis virus type III and simian rotavirus in virus contaminated sewage and drinking water. They recommended active aluminum oxide as an adsorbent for the elimination of enteroviruses from water. Hyrin et al. (1999) studied the sorption properties of natural and activated specimens of saponite with respect to poliomyelitis virus, Coxsackie B 1 and B 6 viruses as well as to Enterobacteriaceae group bacteria.

Mechanisms were discussed regarding the decontaminating effect of thermoactivated saponite in water. Divizia et al. (1999b) discuss the genomic characterization of human and environmental polioviruses isolated in Albania during a poliomyelitis outbreak in 1996. Their study confirmed the environmental circulation in Albania of recombinant poliovirus strains, probably sustained by a massive vaccination effort and by the presence in the environment of a type 1 poliovirus (isolated from the Lana River in Tirana, Albania approximately two months before the first case of symptomatic acute flaccid paralysis was reported in that town). Kaupert et al. (1999) studied the effect of gamma radiation on poliovirus infectivity seeded in sludge samples. This was done in order to determine the radiation dose required to inactivate 90% of viral infectivity (D10). A D10 of 3.34 kGy was determined for poliovirus type III, Sabin strain, suspended in sludge samples. This value dropped to 1.92 kGy when the virus was suspended in water. Manor et al. (1999b) 1994 . Between 1989 and 1997 sewage samples were processed in the laboratory with a double-selective tissue culture system. Wild-type poliovirus was isolated from 17 of them in four clusters, termed "silent outbreaks." The AFP surveillance failed to detect the circulating wild-type viruses. Their study emphasized the important role that environmental surveillance can play in monitoring the eradication of polioviruses. Muscillo et al. (1999) performed the molecular and biological characterization of poliovirus 3 strains isolated from Adriatic seawater samples. Previous studies by the authors using RT-PCR had identified the presence of poliovirus type 3 (P3). In order to better estimate the risk to human health of these occurrences in bathing water, the authors developed a protocol to distinguish wild from Sabin P3 strains. Three sets of RT-PCR primers were engineered. Eight reference American Type Culture Collection (ATCC) reference strains, whose sequences were known, were also evaluated under the same experimental conditions. Egglestone et al. (1999) collected samples of sewage, seawater, river water, sand and silt from a sewage works at Weston-super-Mare, England and from coastal areas nearby over a period of several weeks during the summer of 1996. Reverse-transcriptase polymerase chain reaction was used to search for human astrovirus (HastV) RNA in concentrates of the samples.

No evidence of astrovirus was found in any of the samples suggesting that contamination with these viruses was not a problem in that area during the summer holiday season. A single case of astrovirus diarrhea was diagnosed in summer at the end of the sampling period, but not in the survey area. However, the authors were able to confirm that poliovirus adsorbs to sand and silt shows that these materials might be able to concentrate other enteric viruses in water to a level that could be a threat to the health of people coming in contact with it.

Gastroenteritis viruses comprise a broad group of agents which include members of the families Adenoviridae (enteric adenoviruses), Astroviridae (astrovirus), Calciviridae (Norwalk group viruses and caliciviruses), Coronaviridae (coronavirus and torovirus) and Reovirdae (rotavirus), (Petric, 1999) . Several viruses which are morphologically analogous to the Norwalk virus have also been referred to Norwalk-like viruses (NLVs) or small round-structured viruses (SRSV). Outbreaks of viral gastroenteritis are usually associated with contaminated water and food. Bon et al. (1999) used enzyme immunoassay or RT-PCR to detect group A rotaviruses, human caliciviruses, astroviruses and adeonoviruses types 40 and 41 in stool specimens from 414 children reporting symptoms of gastroenteritis between 1995 and 1998. The results of their study indicated the importance of caliciviruses in infantile gastroenteritis. The authors also noted the predominance of Norwalk-like viruses belonging to genogroup II.

PCR and a molecular beacon probe were used by Poddar (1999) for the detection of Adenovirus. The results of this study indicated that the detection limit of adenovirus by PCR in the presence of molecular beacon probe was found to be similar to that obtained by linear probe hybridization following PCR. A study was undertaken by Qiao et al. (1999) Detection of HAV, SRSV, and astrovirus genomes from native oysters in Chiba City, Japan was reported by Kitahashi et al. (1999) . The results of their study indicated that both SRSV and astrovirus were predominantly distributed into naturally grown oysters in the winter season. SRSV and astrovirus appear to contribute mainly to the food-born outbreaks of gastroenteritis which occur as a result of eating contaminated oysters.

Durborow (1999) discussed the avoidance, control, and treatment of a wide range of maladies contracted by humans from fish including the shellfish origin of Norwalk virus infection in a review article. Hardy (1999) reviewed current understanding of Norwalk and Norwalk-like viruses in epidemic gastroenteritis. According the review, prior to 1990, the only nucleotide sequence information for caliciviruses was from viruses isolated from animals.

Currently, there are now sequences available for more than 100 NLV viruses and more are rapidly accumulating. This type of information is being used for the development of new and more sensitive diagnostic assays. Reina and Ballesteros (1999) reviewed caliciviruses, the virus which is reported to emerge in ocean reservoirs. O'Ryan et al. (1999) studied the presence of Norwalk (NV) and Mexico (MX) virus, two human caliciviruses in stools of Chilean children from different settings. Despite the high seroprevalence, NV and MX viruses were detected in a very low proportion of Chilean children stools. Kukkula et al. (1999) described the outbreak of viral gastroenteritis that was the result of drinking water contaminated by Norwalk-like viruses in Heinavesi, a Finnish municipality.

Municipal water consumption was found to be associated with illness. Cama et al. (1999) evaluated enteropathogens and other factors associated with severe disease in children with acute water diarrhea in Lima, Peru. Three hundred eighty one children less than five years of age who had been hospitalized with diarrhea and moderate to severe dehydration and 381 age-sex-, and date-of-visit-matched outpatient children with mild-diarrhea were studied. Rotavirus was detected in 52% of the in-patients and 35% of the out-patients. They found that the risk of severe diarrhea was particularly great in children who were not exclusively breast-fed in early infancy and who also lacked piped water in their homes.

Naficy et al. (1999) performed a study to describe the epidemiology of rotavirus diarrhea in a population-based cohort of children under 3 years of age residing in Abu Homos, Egypt, in 1995 Egypt, in -1996 . They concluded that the use of effective immunization against rotavirus in early infancy should be considered a public health priority. Brugha et al. (1999) Myrmel et al. (1999) developed a detection method for small round structured viruses in artificially contaminated deionized water and raw drinking water. The sensitivity of their method corresponded to a positive SRSV in 500 ml deionized water with an estimated concentration of 0.5 -5 virus particles per ml.

Schvoerer et al. (1999) Takada et al. (1999) evaluated avirulent avian influenza virus as a vaccine strain against a potential human pandemic. They report that surveillance of birds and animals, particularly aquatic birds for viruses to provide vaccine strains, especially surrogate viruses, for a future pandemic is stressed.

Flow cytometry (FCM) was successfully utilized by Marie et al. (1999) to enumerate viruses in seawater after staining with the nucleic acid specific dye SYBR Green-I. Because of its speed and accuracy, FCM should prove very useful for studies of virus infection in cultures and should allow better understanding of the structure and dynamics of virus populations in natural waters.

A one-month study comparing one-step hydrogen peroxide and a multipurpose disinfection solution for contact lenses was carried out in the absence of tap water rinsing.

Acanthamoeba was not isolated from any lenses storage case, with the multipurpose solution giving the lowest rate of bacterial contamination. The modified Field's staining technique was used by Pirehma et al. (1999) to identify Acanthamoeba sp. The authors indicate that the sharp color contrast, short time required, and low number of reagents used make it a practical procedure for field use. Genus and subgenus-fluorescent oligonucleotide probes have been developed for staining of Acanthamoeba in situ (Stothard, 1999) . The former was tested using both cultured trophozoites and cysts in corneal scrapings and the sub-genus probe was indicated to have potential in detection of the subgroup most closely associated with Acanthamoeba keratitis.

Cryptosporidium and Giardia are the two most widely recognized protozoan pathogens for which a waterborne route of transmission has been demonstrated. Both cause chronic diarrheal disease, particularly in immunosupressed individuals. The organisms undergo a complex life cycle during which cysts or oocysts are produced. These structures are highly resistant to disinfection but still remain infectious. Infectious dose for both organisms is extremely low with as few as 10 to 30 cysts or ooocysts capable of causing clinical infection. Cryptosporidium is now recognized as a common cause of diarrhea throughout the world. Although more than 20 species of Cryptosporidium are now recognized, only one, C. parvum is considered to be a human pathogen. Giardiasis is caused by Giardia lamblia, recently renamed G. duodenalis. Gasser and O'Donoghue (1999) reviewed 11 papers from the Consensus Conference on

Cryptosporidium in Water. The papers address the current technologies used to grow and characterize clinical isolates. Lindquist et al. (1999) developed a set of criteria to evaluate the many new methods being proposed for detection of the protozoan pathogens Cryptosporidium parvum and Giardia lamblia. They suggested that these methods be used by those individuals who are evaluating current methods as well as those in the process of developing new methods.

Zuckerman et al. (1999) developed a portable continuous flow centrifugation device for the recovery of Cryptosporidium oocysts and Giardia cysts from large volumes of water. The collected oocysts and cysts were detected using immunofluorescence. The authors indicated that this device is an improvement over current technology and has potential application for drinking water utilities. Sentinel chambers were used by Jenkins et al. (1999) to test the effect of environmental stresses on purified oocysts. Viability was determined using a dye permeability assay. Increased inactivation rates were found in the presence of increasing temperature and decreasing water potential. Oocysts inoculated into waste piles and soil were also inactivated more rapidly than controls.

Chung et al. (1999) developed a PCR method using an internal standard allowing them to quantitatively detect C. parvum oocysts in municipal drinking water. Using this method they were able to quantify C. parvum in oocyst-spiked municipal drinking water. Kostrzynska et al. (1999) described protocols to be used on fecal matter and environmental waters in preparation for PCR detection of C. parvum from these samples. They obtained greater sensitivity when a nested PCR procedure was used. Two predominant C. parvum genotypes were detected when 25

isolates from Canadian crytosporidosis cases were assayed using a nested PCR (Ong et al., 1999) . Hsu et al. (1999) used an immunofluorescence assay for the simultaneous detection of Giardia cysts and Cryptosporidium oocysts in 31 raw and potable water samples collected from water treatment plants. Detection of both cysts and oocysts indicated that water transmission of these organisms if the water is improperly treated. Using an improved immunofluorescence assay Deng and Cliver (1999) were able to detect G. lamblia cysts and C. parvum oocyst in adult cervine animals which did not exhibit signs of illness. These results suggest that these animals could potentially serve as a source of infection for humans and other animals.

Hallier-Soulier and Guillot (1999) used a combination of immunomagnetic separation of C. parvum with PCR to detect low levels of the protozoan. Using this combined assay, they were able to detect one oocyst added to five 100 liter samples. Studies on surface and filter backwash water were carried out using immunomagnetic separation coupled with in vitro culture and PCR (CC-PCR). As a comparison, samples were also assayed using Percoll-sucrose flotation with immunofluorescence for detection of oocysts. The authors reported comparable results when tested on seeded samples (DiGiovanni et al., 1999) . Rochelle et al. (1999) evaluated the Dynal and Crypto-Scan immunomagnetic separation (IMS) kits for C. parvum oocyst recovery. They observed that the type of agitiation used in the procedure affected the ability to recover oocysts and that IMS recovered oocysts maintained their infectivity. Slifko et al. (1999) adapted a cell-culture infectivity assay to use in the development of a focus detection method (FDM)-most probably number (MPN) assay. Their studies indicated that this is an effective method for cell-culture systems and suggest it could be used by individuals testing environmental waters.

C. parvum was found to be endemic in young children in Pakistan. A significantly higher infection rate was found in children with diarrhea compared with those that did not have diarrhea (Iqbal et al.,1999) . Tamburrini and Pozio (1999) determined that seawater and infected mussels could be a source of C.parvum for human infection. C. parvum oocysts were found to remain infectious after a one year incubation in artifical seawater. Oocysts were also observed to maintain their infectivity for 14 days in mussels. C. parvum oocysts were detected in Chesapeake Bay Bent mussels collected from areas where oocyst contaminated oysters were previously found. Oocysts were also able to be isolated from spiked blue mussel tissue. The researchers suggested that Bent mussels, which have wide distribution in the bay, may be valid biological indicators of Cryptosporidium contaminated water (Graczyk et al., 1999b) . Oysters were collected from seven sites in Chesapeake Bay that are used for commercial harvesting. Assay of these oysters indicated that C. parvum oocysts were present (Fayer et al., 1999) . Graczyk et al. (1999a) suggest that the Asian freshwater clam can be used as a biological monitor for contamination with Giardia. Using 160 clams in a 38 liter aquarium, spiked with 10 5 Giardia duodenalis cysts they were able to demonstrate the presence of cysts in clam tissue for up to three weeks after exposure. Water borne cysts were not detectable using the membrane filter technique 90 minutes after seeding the water. Giardia duodenalis Genotype A cysts were detected in Chesapeake Bay Macoma clams by Graczyk et al. (1999c) . Since Genotype A is the one most commonly associated with human infection, the suggest using Macoma clams as biological indicators for the presence of Giardia cysts. Levesque et al. (1999) analyzed over 4000 giardiasis cases in Quebec in an attempt to detrermine if a relationship existed between illness and drinking water quality. They found a lower incicence of giardiasis where the St. Lawrence river was used as the source of drinking water. They suggested that this might not be due to lower levels of contamination present in this source, but other variable should also be considered. Franzen and Muller (1999) reviewed the literature on cryptosporidia and microsporidia from a public health perspective. Sources of organisms, modes of transmission and reservoirs were considered. Dowd et al. (1999) compared the use of immunofluorescent analysis (IFA) and PCR for the detection of microsporidia in water. Their results indicated that IFA was an unacceptable method. The two methods used to isolate DNA from water as a source for PCR coupled with PCR were found to detect low levels of spores in water.

Cotte et al. (1999) report that an analysis of over five thousand stool samples for microsporidia over the three year period of 1993 to 1996 yielded positive results in approximately 300 samples. The majority of these individuals were HIV positive.

A waterborne outbreak of microsporidiosis occurred in the summer of 1995. Fecal contamination of the water was not detected. Use of a specific water distribution subsystem appeared to me the major fa ctor associated with diagnosis of the disease. Koudela et al. (1999) demonstrated that Encephalitozoon cuniculi spores can survive low (freezing) temperatuares when they are suspended in water, but rapidly lose infectivity at 60 o C.

Aramini et al. (1999) 

Outbreak of Escherichia coli O157:H7 and Campylobacter Among Attendees of the Washington County Fair-New York. MMWR Morb Mortal Wkly Rep

A Strategy for Detection of Viruses in Groundwater by PCR

Salmonella Infection in Children from the Wastewaterspreading Zone of Marrakesh City (Morocco)

Occurrence of Haemolytic & Cytotoxic Aeromonas Species in Domestic Water Supplies in Chennai. Indian J. Med Isolates Recovered from AIDS and Non-AIDS Patients with those of Isolates from Potable Water

Enteric Viruses and Other Microorganisms of Fecal Origin in Waters Affected by Sewage Effluents

Animals as a Source of Infections for Humans--Diseases Caused by EHEC

Inactivation of Crykptosporidium parvum Oocyst Infectivity by Disinfection and Sterilization Processes

Pathogenicity of Halophilic Vibrio spp. and Non-O1 Vibrio cholerae from Estuarine Waters Along the

Seroprevalence of Helicobacter pylori, Incidence of Gastric Cancer, and Peptic Ulcer-Associated Hospitalizations in a Canadian Indian Population

Aeromonas hydrophila Bacteremia Acquired from an Infected Swimming Pool

Verocytotoxin-producing Escherichia coli O157: public health and microbiological significance

Copyright © 2000 by the Water Environment Federation

Presence of Campylobacter and Salmonella in Sand from Bathing Beaches

Prevalence of Group A Rotavirus, Human Calicivirus, Astrovirus, and Adenovirus Type 40 and 41 Infections Among Children With Acute Gastroenteritis

Reduction of Microorganisms in Sewage Effluent Using Hypochlorite and Peracetic Acid as Disinfectants

Antibiotic Resistance of Native and Faecal Bacteria Isolated from Rivers, Reservoirs and Sewage Treatment Facilities in Victoria, South-Eastern Australia

Sewer Workers: Occupational Risk for Hepatitis C--Report of Two Cases and Review of Literature

Iodine Disinfection of a Model Bacteriophage, MS2, Demonstrating Apparent Rebound

A Neural Network Approach to Identifying Non-Point Sources of Microbial Contamination

Community Outbreak of Legionnaires' Disease

Linked to Hospital Cooling Towers: An Epidemiological Method to Calculate Dose of Exposure

A Community Outbreak of Food-Borne Small Roundstructured Virus Gastroenteritis Caused By a Contaminated Water Supply

Enteropathogens and Other Factors Associated With Severe Disease in Children With Acute Watery Diarrhea in Lima

Recovery in Embryonated Eggs of Viable but Nonculturable Campylobacter Jejuni Cells and Maintenance of Ability to Adhere to HeLa Cells after

Assessment of Microbial Parameters as Indicators of Viral Contamination of Aerosol from Urban Sewage Treatment Plants

Chlorine Disinfection of Recreational Water for Cryptosporidium parvum

Legionnaires' Disease on a Cruise Ship Linked to the Water Supply System: Clinical and Public Health Implications

Viable Heterotrophic Bacteria in Water and Sediment in 'Mar Piccolo' of Taranto

Fate of Cryptosporidium Oocysts, Giardia Cysts, and Microbial Indicators During Wastewater Treatment and Anaerobic Sludge Digestion

PCR-Based Quantitaton of Cryptosporidium parvum in Municipal Water Samples

Routine Detection of Salmonella Species in Water: Comparative Evaluation of the ISO and PROBELIA Polymerase Chain Reaction Methods

The Unique Riverine Ecology of Hepatitis E Virus Transmission in South-East Asia

Waterborne Outbreak of Intestinal Microsporidiosis in Persons With and Without Human Immunodeficiency Virus Infection

Occurrence of Nontuberculous Mycobacteria in Environmental Samples

Detection of Hepatitis A Virus in Shellfish by Nested Reverse Transcription-PCR

Water and Nontuberculous Mycobacteria

Ribotypes of Clinical Vibrio cholerae Non-O1 Non-O139 Strains in Relation to O-serotypes

Rapid Transport of Viruses in a Floodplain Aquifer

Improved Immunofluorescence Assay for Detection of Giardia and Cryptosporidium from Asymptomatic Adult Cervince Animals

Molecular Confirmation of Hepatitis A Virus from Well Water: Epidemiology and Public Health Implications

Detection of Infectious Cryptosporidium parvum Oocysts in Surface and Filter Backwash Water Samples by Immunomagnetic Separation and Integrated Cell Culture-PCR

Copyright © 2000 by the Water Environment Federation

Genomic Characterization of Human and Environmental Polioviruses Isolated in Albania

HAV and HEV Infection in Hospitalised Patients in

An Accelerated Method for Detecting Coliphages in the Drinking Water

Evaluation of Methodologies Including Immunofluorescent Assay (IFA) and the Polymerase Chain Reaction (PCR) for Detection of Human Pathogenic Microsporidia in Water

Risk Screening for Exposure to Groundwater Pollution in a Wastewater Irrigation District of the Mexico City Region

Health and Safety Concerns in Fisheries and Aquaculture

Absence of Human Astrovirus RNA in Sewage and Environmental Samples

Temporal and Spatial Variations of Coliforms and Escherichia coli in Fluvial Recreational Waters

Relationship with the Quality Standards

Copyright © 2000 by the Water Environment Federation

Cryptosporidium parvum in Oysters from Commercial Harvesting Sites in the Chesapeake Bay

Sedimentary 4-Desmethyl Sterols and n-Alkanols in an Eutrophic Urban Estuary

Microbiological Safety of Drinking Water: United States and Global Perspectives

Cryptosporidia and Microsporida --Waterborne Diseases in the Immunocompromised Host

Enterovirus Genome Detection in Wastewater: Multi Centric Evaluation of a Commercial Kit

Isolation, Propagation and Characterization of Cryptosporidium

Isolation of Vibrio vulnificus from Sea Water and Sand Along the Dan Region Coast of the Mediterranean

Waterborne Microbiological Risk Assessment: A State of the Art and Perspectives

Salmonella and Salmonellosis in the Asturias District, Spain, During a Seven Year Period (1990-1996)

Assessment of Cell Culture and Polymerase Chain Reaction Procedures for the Detection of Polioviruses in Wastewater

Elimination of Viruses, Phages, Bacteria and Cryptosporidium by a New Generation Aquaguard Point-of-Use Water Treatment Unit

Evaluation of the Recovery of Waterborne Giardia Cysts by Freshwater Clams and Cyst Detection in Clam Tissue

Cryptosporidium Oocysts in Bent Mussels (Ischadium recurvum) in the Chesapeake Bay

Giardia duodenalis Cysts of Genotype A Recovered from Clams in the Chesapeake Bay Subestuary, Rhode River

Comparative Detection of Enteric Viruses in Wastewaters, Sediments and Oysters by Reverse Transcription-PCR and Cell Culture

Copyright © 2000 by the Water Environment Federation

Pontiac Fever at a Sewage Treatment Plant in the Food Industry

Detection of Viral Pathogens By Reverse Transcriptase PCR and of Microbial Indicators by Standard Methods in the Canals of the Florida Keys

Identification of Enteroviruses in Environmental Samples Using PCR Coupled With a Colorimetric Microwell Method

Simple Method of Detecting Enteroviruses in Contaminated Molluscs and Sewage by Using Polymerase Chain Reaction Coupled with a Colorimetric Microwell Detection Assay

Semi-Quantitative Characterization of Electroporation-Assisted Disinfection Processes for Inactivation of Giardia and Cryptosporidium

Determining Sources of Fecal Pollution in a Rural Virginia Watershed with Antibiotic Resistance Patterns in Fecal Streptococci

The Health Effects of Swimming in Ocean Water Contaminated by Storm Drain Runoff

An Immunomagnetic Separation Polymerase Chain Reaction Assay for Rapid and Ultra-Sensitive Detection of Cryptosporidium parvum in drinking water

Norwalk and "Norwalk-like Viruses

Isolation of Fecal Coliform Bacteria from the Diamondback Terrapin (Malaclemys terrapin centrata)

Prevalence of Enteric Hepatitis A and E in the Mekong River Delta Region of Vietnam

Occurrence of Helicobacter pylori in Surface Water in the United States

Generalized Transduction of Small Yersinia enterocolitica Plasmids

Generalized Mycobacterium genavense Infection in HIV-Infected Patients: Detection of the Mycobacterium in Hospital Tap Water

Cold Tap Water as a Source of Fatal Nosocomial Pneumonia due to Legionella pneumophila in a Rehabilitation Center

Isolation of Enterohaemorrhagic Escherichia coli from Municipal Sewage

Copyright © 2000 by the Water Environment Federation

The Prevalence of Giardia and Cryptosporidium in Taiwan Water Supplies

Seasonal Variation of Campylobacter Types from Human Cases, Veterinary Cases, Raw Chicken, Milk and Water

Agricultural Land-Use Effects on the Indicator Bacterial Quality of an Upland Stream in the Derbyshire Peak District in the

Microbiological Quality of Drinking Water from Office Water Dispensers

The Use of the Natural Mineral Saponite for Water Decontamination

Environmental Factors Affecting the Occurrence of Mycobacteria in Brook Sediments

Risk Analysis of Poor Health and Growth Failure of Children in the Central Highlands of Guatemala

Cryptosporidium Infection in Young Children with Diarrhea in Rawalpindi

Association of Vibrio cholerae O1 with the Cyanobacterium, Anabaena sp., Elucidated by Polymerase Chain Reaction and Transmission Electron Microscopy

Copyright © 2000 by the Water Environment Federation

Use of a Sentinel System for Field Measurements of Cryptosporidium parvum Oocyst Inactivation in Soil and Animal Waste

Prevention and Treatment of Traveler's Diarrhea

Inactivation of Poliovirus by Gamma Irradiation of Wastewater Sludges

Hospital Water Supply as a Source of Disseminated Mycobacterium fortuitum Infection in a Leukemia Patient

Waterbirths: Regional Audit of Infection Control Practices

Detection of HAV, SRSV, and Astrovirus Genomes From Native Oysters in Chiba City

Detecting Legionellosis by Unselected Culture of Respiratory Tract Secretions and Developing Links to Hospital Water Strains

Effect of Monochloramine Disinfection of Municipal Drinking Water on Risk of Nosocomial Legionnaires' Disease

Literature Review 2000. for Polymerase Chain Reaction Based Detection of Cryptosporidium parvum in Environmental Samples

Effect of Low and High Temperatures on Infectivity of Encephalitozoon cuniculi Spores Suspended in Water

Longevity of Pathogenic Bacteria Especially Salmonella in Cistern Water

Quantitative Bacterial Examination of Domestic Water Supplies in the Lesotho Highlands: Water Quality, Sanitation, and Village Health

Biocontrol of Eschericia coli 0157 with 0157-Specfic Bacteriophages

Outbreak of Viral Gastroenteritis Due to Drinking Water Contaminated by Norwalk-like Viruses

Abundance and Distribution of Bacteria Carrying sltII Gene in Natural River Water

Isolation of Avian Influenza Viruses in Central Oklahoma

Occurrence and Levels of Phages Proposed as Surrogate Indicators of Enteric Viruses in Different Types of Sludges

Copyright © 2000 by the Water Environment Federation

Single Clonal Origin of a High Proportion of Legionella pneumophila Serogroup 1 Isolates from Patients and the Environment in the Area

The Epidemiology of Viral Hepatitis in Children in South Texas: Increased Prevalence of Hepatitis A Along the Texas-Mexico Border

Occurrence of Hepatitis A Virus in Green-Lipped Mussels (Perna Viridis)

Occupations at Increased Risk of Hepatitis A: A 2-year Nationwide Historical Prospective Study

Study of the Incidence of Giardiasis in Quebec (Canada) and Association with Drinking Water Source and Quality

Seroepidemiology of Helicobacter pylori Infection Among Preschool Children in Taiwan

Criteria for Evaluation of Proposed Protozoan Detection

Helicobacter pylori Infection in Ethiopian Children: a Cohort Study

Copyright © 2000 by the Water Environment Federation

Seroepidemiology of Helicobacter pylori Infection in a Jamaican Community

Molecular Detection of Norwalk-like Caliciviruses in Sewage

An Outbreak of Pontiac Fever among Children and Adults Following a Whirlpool Bath

Virus Passage Through Track-Etch Membranes Modified by Salinity and Nonionic Surfactant

Electrophoretic Mobilities of Escherichia coli O157:H7 and Wild-Type Escherichia coli Strains

A Double-Selective Tissue Culture System for Isolation of Wild-Type Poliovirus from Sewage Applied in a Ling-Term Environmental Surveillance

Detection of Poliovirus Circulation by Environmental Surveillance in the Absence of Clinical Cases in Israel and the Palestinian Authority

Copyright © 2000 by the Water Environment Federation

Mycobacterium leprae DNA in Daily Using Water as a Possible Source of Leprosy Infection

Enumeration of Marine Viruses in Culture and Natural Samples by Flow Cytometry

Uptake and Retention of Vibrio cholerae Non-O1, Salmonella typhi, Escherichia coli and Vibrio harvey by Mussels in Seawater

Hepatitis E Virus Seroprevalence in Children Living in Rural Ghana

An Outbreak of Acute Gastroenteritis in a Geriatric Long-Term-Care Facility: Combined Application of Epidemiological and Molecular Diagnostic Methods

Isolation of Sublethally Injured Campylobacters from Poultry and Water Sources

Helicobacter pylori in the Canadian Arctic: Seroprevalence and Detection in Community Water Samples

Copyright © 2000 by the Water Environment Federation

The Fate of Environmental Coliforms in a Model Water Distribution System

An Outbreak of Campylobacter Enteritis on an Island Resort, North Queensland

Temporal and Geographical Distributions of Reported Cases of Escherichia coli O157:H7 Infection in Ontario

Comparative Study of Techniques Used to Recover Viruses from Residual Urban Sludge

Comparative Survival of Free Shiga Toxin 2-Encoding Phages and Eschericia coli Strains Outside the Gut

Occurrence and Numbers of Bacteriophages and Bacterial Indicators in Faeces of Yellow-Legged Seagull (Larus cachinnans)

Study of the Potential Relationship Between the Morphology of Infectious Somatic Coliphages and their Persistence in the Environment

Genotypic Characterization of Human and Environmental Isolates of Salmonella choleraesuis subspecies choleraesuis serovar Infantis by Pulsed-Field Gel Electrophoresis

Copyright © 2000 by the Water Environment Federation

Molecular and Biological Characterization of Poliovirus 3 Strains Isolated in Adriatic Seawater Samples

Detection of Small Round Structured Viruses in Artificially Contaminated Water Using Filter Adsorption and Reverse Transcription Polymerase Chain Reaction

Epidemiology of Helicobacter pylori: Transmission, Translocation and Extragastric Reservoirs

An Outbreak of Legionnaire's Disease Associated with a Japanese Spa

Epidemiology of Rotoavirus Diarrhea in Egyptian Children and Implications for Disease Control

Quantitative Assessment of the Inactivation of Pathogenic and Indicator Viruses in Natural Water Sources

DNA Probes Specific for Aeromonas hydrophila (HG1)

Distribution and Seasonality of Microbial Indicators and Thermophilic Campylobacters in Two Freshwater Bathing Sites on the River Lune in Northwest England

The Effect of a New Sewage Treatment Plant on Faecal Indicator Numbers, Campylobacters and Bathing Water Compliance

Molecular Epidemiology of Cryptosporidiosis Outbreaks and Transmission in British Columbia

Detection of Norwalk and Mexico Viruses, Two Human Caliciviruses in Stools of Chilean Children

Discriminant Analysis of Ribotype Profiles of Escherichia coli for Differentiating Human and Nonhuman Sources of Fecal Pollution

Swimming-Associated Outbreak of Escherichia coli O157:H7

Poor Efficacy of Residual Chlorine Disinfectant in Drinking Water to Inactivate Waterborne Pathogens in Distribution Systems

An International Outbreak of Vero Cytotoxin-Producing Escherichia coli O157 Infection

Amongst Tourists; a Challenge for the European Infectious Disease Surveillance Network

Nucleic Acid Extraction from Polluted Estuarine Water for Detection of Viruses and Bacteria by PCR and RT-PCR Analysis

Caliciviruses, Astroviruses, and Other Diarrheic Viruses

Field's Stain --a Rapid Staining Method for Acanthamoeba spp

Detection of Adenovirus Using PCR and Molecular Beacon

Prevalence of Salmonella Serotypes in Environmental Waters and their Relationships with Indicator Organisms

The Search for Enterovirus in Surface Waters via RT-PCR: Experience on the Ticino River

Use of PNA Oligonucleotides for the in situ Detection of Escherichia coli in Water

Diversity of Bacteroides fragilis Strains in their Capacity to Recover Phages from Human and Animal Wastes and From Fecally Polluted Wastewater

Genomic Structure of Phage B40-8 of Bacteroides fragilis

Sensitive Detection of Escherichia coli O157:H7 in Food and Water by Immunomagnetic Separation and Solid-Phase Laser Cytometry

Viral Diarrhea in Children in Bejing

Diarrhoea Prevention in Bolivia Through Point-Of-Use Water Treatment and Safe Storage: a Promising New Strategy

The Norway Rat as a Reservoir Host of Cryptosporidium parvum

Molecular Characterization of Vibrio cholerae O1 and Non-O1 from Human and Environmental Sources in Malaysia

The Relationship Between E. coli Indicator Bacteria in Well-Water and Gastrointestinal Illnesses in Rural Families

Use of Selective Media to Recover Salmonella and Vibrio cholerae after Growth in Reconditioned Pork-Processing Wastewater

Recovery and Survival of Escherichia coli O157:H7 in Reconditioned Pork-Processing Wastewater

Microbial Quality of Oysters Sold in Western Trinidad and Potential Health Risk to Consumers

Outbreak of Gastroenteritis Associated with Contamination of a Private Borehole Water Supply

Calicivirus. The Virus Which Emerges in Ocean Reservoirs

Sorbitol-Fermenting Bifidobacteria as Indicators of Diffuse Human Faecal Pollution in Estuarine Watersheds

Chlorine Inactivation of Escherichia coli O157:H7. Emerg

Isolation of Arcobacter butzleri from Ground Water

Evaluation of Immunomagnetic Separation for Recovery of Infectious Cryptosporidium parvum Oocysts from Environmental Samples

Bacterial Growth State Distinguished by Single-Cell Protein Profiling: Does Chlorination Kill Coliforms in Municipal Effluent?

Health Effects Among Workers in Sewage Treatment Plants

Growth of Starved Escherichia coli O157 cells in Selective and Non-Selective Media

Helicobacter pylori in the

A Hospital Outbreak of Gastroenteritis Possibly Related to the Contamination of Tap Water by a Small Round Structured Virus

Transduction of Enteric Escherichia coli Isolates with a Derivative of Shiga Toxin 2-Encoding Bacteriophage φ3538 Isolated from Escherichia coli 0157:H7

Disinfection of Contact Lenses Without Tap Water Rinsing: Is it Effective? Eye, 13

Characterization of Pseudomonas aeruginosa Bacteriophage UNL-1, a Bacterial Virus with a Novel UV-A-Inducible DNA Damage Reactivation Phenotype

Copyright © 2000 by the Water Environment Federation

Transmission of Epidemic Vibrio cholerae O1 in Rural Western Kenya Associated with Drinking Water from Lake Victoria: an Environmental Reservoir for Cholera? Am

A Method to Detect Low Levels of Enteric Viruses in Contaminated Oysters

Persistent High Risk of Diarrhea Among Foreigners in Nepal During the First 2 Years of Residence

Sunlight Inactivation of Fecal Bacteriophages and Bacteria in Sewage-Polluted Seawater

A Most-Probable-Number Assay for Enumeration of Infectious Cryptosporidium parvum Oocysts

The Effect of Wind Speed and Direction on the Distribution of Sewage-Associated Bacteria

) Occurrence, Removal and Seasonal Variation of Thermophilic Campylobacters and Arcobacter in Sewage Sludge

Biofilm Formation by Helicobacter pylori

Copyright © 2000 by the Water Environment Federation

Fluorescent Oligonucleotide Probes for Clinical and Environmental Detection of Acanthamoeba and the T4 18S rRNA Gene Sequence Type

Transmission of Helicobacter pylori

Hepatitis A Incidence Rate Estimates From a Pilot Seroprevalence Survey in Rio de Janeiro

Avian Influenza Virus as a Vaccine Strain Against a Potential Human Pandemic

Long-Term Survival of Cryptosporidium parvum Oocysts in Seawater and in Experimentally Infected Mussels (Mytilus galloiprovincialis)

Considerations Regarding Mass Vaccination Against Typhoid Fever as an Adjunct to Sanitation and Public Health Measures: Potential Use in an Epidemic in Tajikistan

Evaluation of the Effect of Temperature and Nutrients on the Survival of Campylobacter spp. in Water Microcosms

Copyright © 2000 by the Water Environment Federation

Bacteriophage Inactivation at the Air-Water-Solid Interface in Dynamic Batch Systems

PCR and the Detection of Microbial Pathogens in Water and Wastewater

Incidence and Risk Factors for Diarrhoea and Acute Respiratory Infections in Urban Communities of Pernambuco

Helicobacter pylori: Characteristics, Pathogenicity, Detection Methods and Mode of Transmission Implicating Foods and Water

A Comparison of Different Culture Media for the Membrane Filter Quantification of Aeromonas in Water

Multiple Types of Legionella pneumophila Serogroup 6 in a Hospital Heated-Water System Associated with Sporadic Infections

Detection of Low Numbers of Pathogenic Yersinia enterocolitica in Environmental Water and Sewage Samples by Nested Polymerase Chain Reaction

Copyright © 2000 by the Water Environment Federation

Detection of Low Numbers of Salmonella in Environmental Water, Sewage and Food Samples by a Nested Polymerase Chain Reaction Assay

Detection of Small Numbers of Campylobacter jejuni and Campylobacter coli Cells in Environmental Water, Sewage, and Food Samples by a Seminested PCR Assay

Seafood-Associated Disease Outbreaks in New York, 1980-1994

Steps in the Development of a Vibrio cholerae El tor Biofilm

Use of Antibiotic Resistance Analysis to Identify Nonpoint Sources of Fecal Pollution

Enterically Transmitted Hepatitis. Hepatitis A and E Viruses

Water Pollution and Human Health in China

An Unexpected Temporal Pattern of Coliphage Isolation in Groundwaters Sampled From Wells at Varied Distances from Reclaimed Water Recharge Sites

Copyright © 2000 by the Water Environment Federation

Vibrio cholerae O1 El Tor: Identification of a Gene Cluster Required for the Rugose Colony Type, Exopolysaccharide Production, Chlorine Resistance, and Biofilm Formation

Differentiation of Vibrio alginolyticus Strains Isolated from Sardinian Waters by Ribotyping and a New Rapid PCR Fingerprinting Method

Evaluation of a Portable Differential Continuous Flow Centrifuge for Concentration of Cryptosporidium Oocysts and Giardia Cysts from Water

Copyright © 2000 by the Water Environment Federation

Amahmid et al. (1999) determined that the use of raw sewage resulted in the contamination of crops with Giardia cysts which persisted on one crop (coriander) for 8 days.The use of treated wastewater or freshwater did not result in contamination. Quy et al. (1999) studied three Norway rat populations living on farmland and attempted to assess their potetnial as reservoirs of C. parvum. They observed C. parvum associated with these populatons and suggested that they could be a source of infection for livestock or humans.An Aquaguard water purifier consisting of a candle prefilter, activated carbon filter and UV irradiation unit was evaluated by Grabow et al. (1999b) . Reverse transcriptase polymerase chain reaction was used to detect seeded C. parvum oocysts and viruses. It was found that this apparatus was effective in removing bacteria, viruses and C. parvum oocysts from water.Haas and Aturaliye (1999) found that a combination of electroporation with combined chlorine, hydrogen peroxide and potassium permanganate resulted in enhanced inactivation of Giardia and Cryptosporidium. They suggest additional studies be done to determine the optinal conditions for control of these organisms in water. Carpenter et al. (1999) considered swimming pool conditions necessary for disinfection of C. parvum. They noted that the presence of fecal matter can change the concentration and time of exposure necessary for effective disinfection. Barbee et al. (1999) addressed the issue of transmission of C. parvum on environmental surfaces and medical devices by testing a variety of commonly used disinfectants and sterilization procedures. The only agent found to inactivate C. parvum greater than 3 logs was 6% and 7.5% hydrogen peroxide. However, since C. parvum rapidly loses infectivity on dry surfaces it was suggested that current disinfection procedures guidelines are valid.