key: cord-330647-w1bpeqzg
authors: Wong, Samson Sai-Yin; Wong, Sally Cheuk-Ying
title: Ebola virus disease in nonendemic countries
date: 2015-05-31
journal: Journal of the Formosan Medical Association
DOI: 10.1016/j.jfma.2015.01.012
sha: 
doc_id: 330647
cord_uid: w1bpeqzg

The 2014 West African outbreak of Ebola virus disease was unprecedented in its scale and has resulted in transmissions outside endemic countries. Clinicians in nonendemic countries will most likely face the disease in returning travelers, either among healthcare workers, expatriates, or visiting friends and relatives. Clinical suspicion for the disease must be heightened for travelers or contacts presenting with compatible clinical syndromes, and strict infection control measures must be promptly implemented to minimize the risk of secondary transmission within healthcare settings or in the community. We present a concise review on human filoviral disease with an emphasis on issues that are pertinent to clinicians practicing in nonendemic countries.

The largest outbreak of Ebola virus disease (EVD) in history has renewed interest in filoviruses and has provided an unprecedented impetus to the development of new therapeutics and vaccines for this highly lethal infection. Hemorrhagic fevers caused by Ebola and Marburg virusesdalso collectively known as filoviral hemorrhagic fever (FHF)dpreviously caused dramatic, albeit limited, outbreaks in central Africa. Their impact on global health was rather small (except in the realm of biological warfare research) because of the high mortality rate, lack of effective antiviral therapies and vaccines, and potential for person-to-person transmission. 1 The 2014 West African outbreak of EVD proved that these filoviruses should no longer be considered as merely regional problems. A short review of EVD and its clinical relevance to the nonendemic countries is presented. The current epidemic is caused by Zaïre ebolavirus; however, references will also be made to the related Marburgvirus, which shares many virological, clinical, and epidemiological characteristics.

Conflicts of interest: The authors have no conflicts of interest relevant to this article.

The order Mononegavirales consists of enveloped, nonsegmented, negative-sense, single-stranded RNA viruses. The Family Filoviridae comprises three genera: Cuevavirus, Ebolavirus, and Marburgvirus. 2 In 2011, the sole species of Cuevavirus, Lloviu cuevavirus, was described. It was discovered during an investigation of massive die-offs of Miniopterus schreibersii bats in France, Spain, and Portugal in 2002; and the virus was detected in bat carcasses collected from northern Spain. 3 The genus Ebolavirus The name "filovirus" describes a unique morphological characteristic of the viruses. The virions are generally filamentous (in Latin, filum means "thread") with a diameter of approximately 80 nm and a highly variable length of 800e14,000 nm. They may also appear as branched filaments, short rods, U-shaped, circular, or hairpin-shaped. 4, 5 The genomes of EBOV and MARV are approximately 19 kb and consist of seven genes (from the 3 0 to 5 0 end): nucleoprotein (NP), VP35, VP40, glycoprotein (GP), VP30, VP24, and RNA-dependent RNA polymerase (L). 4, 6 Ebolavirus expresses an additional protein through transcriptional editing of the GP gene. In addition to GP, a smaller secreted glycoprotein (sGP) is produced and excreted extracellularly. 4, 7 At 20 C, EBOV and MARV are stable and resist desiccation, which probably explains their stability in aerosol droplets. 7, 8 They are however inactivated by heat and common disinfectants such as detergents, phenolics, and hypochlorites. 7 The usual heat treatment of clinical samples at 56 C for 30 minutes may fail to render the specimen noninfectious. Thermal inactivation at 60 C for 60 minutes or 75 C for 30 minutes is necessary. 9e11 Gamma irradiation readily inactivates the filoviruses, although this method may not be readily available in routine clinical or laboratory settings. 12 The genetics and molecular biology of the filoviral genome have been previously reviewed. 4, 7 In addition to the essential functions for viral replication and assembly, many viral proteins exert their effects on the host immune system and may contribute to the pathogenesis of the infection (Table 1) . 4,7,13e15,26,191,192 For example, VP35 and VP24 inhibit the normal antiviral activities of type I interferons at multiple steps of the pathway, whereas sGP may contribute to immune evasion by absorbing anti-GP antibodies (i.e., antigenic subversion). 13e15 Because of the essential roles of many viral proteins in replication and assembly, some viral proteins (e.g., VP30 and VP35) are potential targets for antiviral agent development. 16, 17 In recent years, the pathogenesis of FHF has been better elucidated. 18 Filoviruses are pantropic with the ability to infect different host cell types. The initial cells in which the viruses replicate are likely dendritic cells, macrophages, monocytes, and Kupffer cells at the site of entry. A large number of lectins (e.g., DC-SIGN and L-SIGN) and immunorecognition receptors [i.e., triggering receptors expressed in myeloid cells (TREM)] can serve as receptors for the viruses. 19 After the initial multiplication in the aforementioned cell types, the viruses are transported to the reticuloendothelial system (e.g., lymph nodes, spleen, liver) and other organs where infection of other cell types occur. The resulting massive necrosis and end organ damage are reflected in the histopathology of human and primate infection models with necrosis in the liver, kidneys, lungs, lymphoid tissues, and other organs. 20, 21 In addition, various mechanisms contribute to the development of coagulopathy and disseminated intravascular coagulation, which is a hallmark of viral hemorrhagic fevers. Patients with FHF develop significant platelet dysfunction (which is not merely accountable for by thrombocytopenia), and this is contributed to by platelet activation and decreased vascular endothelium production of prostacyclin. 22 Another important target in the pathogenesis of FHF is the endothelium. Human and primate endothelial cells are susceptible to infection by EBOV, although direct cyopathic effects are not an important factor in the development of vasculopathy and coagulopathy. 23 The release of vasoactive Table 1 Filovirus genes and their functions. 4,7,13e15,26,191,192 factors (e.g., nitric oxide) or cytokines and chemokines from monocytes and macrophages (e.g., tumor necrosis factor-alpha, interferons, monocyte chemoattactant protein-1, interleukin-8) could be important in the genesis of vascular damage. 23 The combined effects of increased secretions of proinflammatory cytokines, activation of the coagulation cascade, consumption and/or reduced production of protein C, thrombocytopenia and platelet dysfunction, hepatic damage with impaired production of coagulation factors, and vascular damage contribute to the development of coagulopathy in FHF. 24 Protective humoral and cellular immune responses can be demonstrated in patients who survive, and antibody levels persist for years. 25 In addition to the various immune evasion mechanisms alluded to previously [e.g., binding of anti-GP antibodies by sGP (i.e., immune subversion), suppression of innate immune responses, and inhibition of interferon pathways], other potential virulence and pathogenic mechanisms of filoviruses such as the NP and VP24 proteins have been identified. 26 The generation of antibodies towards GP is critical for the protective efficacy of vaccines. 27 

Ebolavirus and MARV are geographically restricted to and cause outbreaks in sub-Saharan Africa; however, REBOV is found in nonhuman primates and pigs in the Philippines (Table 2) . 5, 68, 80, 176, 193, 194 The first filovirus was discovered in 1967 after an outbreak of Marburg hemorrhagic fever infection in Germany. This infection originated from Cercopithecus aethiops monkeys that were imported from Uganda. 28 In 1976, the first natural outbreak of ZEBOV occurred in northern Zaïre (now called the Democratic Republic of the Congo). 29 In 1976, SEBOV was discovered in an outbreak in Nzara in Sudan. 30 In 2007e2008, BEBOV caused an outbreak in Uganda, followed by another outbreak in the Democratic Republic of the Congo in 2012. 31, 32 In 1994, TAFV was discovered in a Swiss biologist who acquired the infection in the Republic of Côte d'Ivoire (i.e., the Ivory Coast). 33 In 1989, REBOV was first discovered in monkeys (Macaca fascicularis) that were exported from the Philippines to Reston, Virginia, USA The infected monkeys were subsequently exported to Italy (1992e1993) and to Texas (1996) . Cynomolgus macaques in the Philippines are naturally infected, as are pigs. The REBOV virus appears to be nonpathogenic to humans. 34e36 Human filovirus infections are primary zoonotic diseases with a high propensity for interpersonal transmission. The primary animal reservoir of EBOV and MARV are bats (especially fruit bats). 37 Bats support long-term viral replication without developing the disease. 38 Virological and serological studies have confirmed filoviral infection in diverse bat species. 37, 39, 40 In the Philippines, China, and Bangladesh, there is also evidence of REBOV (and possibly other filoviral) infection in bats. 41e43 Cases of FHF have been epidemiologically linked to contact with bat carcasses, spelunking among tourists, and outbreaks among gold miners who work in caves. 44e46 Peak seasons of bat MARV infection have been correlated with the incidence of human "spillover"infections. 47 Primates are also naturally infected with filoviruses, although they are likely to be infected by natural reservoir hosts (e.g., bats) and are not considered important reservoirs. 48, 49 Primates, nevertheless, remain important vectors for the introduction of the disease into humans in rural Africa, and wild animal mortality sometimes precede human outbreaks of EVD. 50 Other mammals that can be infected by EVD include pigs (especially by REBOV and ZEBOV) and dogs; however, their role in causing human EVD outbreaks is uncertain. 51e53 Human infections typically occur with a few patterns of transmission. Inhabitants of endemic areas, especially individuals dwelling in forests with occupational exposure to wild animals (e.g., hunters and people handling bushmeat), may develop symptomatic or subclinical infections, presumably because of the exposure to animal reservoirs of the virus. In some cases of human infection, a history of direct exposure to animal carcasses (such as primates, bats, duiker antelopes, and porcupines) or indirect exposure to bats in caves has occurred. 44e46,54,55 These single or multiple introductions to human populations may result in short chains of human transmission. When FHF patients are admitted to healthcare facilities where infection control measures are inadequate, a large outbreak may occur with transmission to other patients and healthcare workers. Hospitals have been a major amplifying and disseminating factor in many previous outbreaks of FHF in Africa.

Direct person-to-person transmission of EBOV and MARV occurs via blood or body fluids by percutaneous inoculation or by mucosal exposures. 56e58 During an outbreak of SEBOV, the virus was detected by viral culture or reverse transcription polymerase chain reaction (RT-PCR) in patients' saliva, skin swab, stool, tears, breast milk, and semen, but not in environmental samples. 59 In view of the persistence of the viruses in semen and breast milk at 91 days and 15 days, respectively, after illness onset, 58,59 the use of condoms and withholding breastfeeding are recommended during convalescence.

More than 80% of patients in the 1995 Kitwit outbreak in the Democratic Republic of the Congo had secondary cases in the household; the risk was highest for people with direct physical contact with the body fluids of symptomatic patients and exposure to patients in the late stages of the disease; this finding can be explained by the high viral load at this phase of disease. 58 Reusing needles or other medical instruments without adequate sterilization, needle stick injuries, lack of isolation facilities, and inadequate and inappropriate use of personal protective equipment all contribute to explosive hospital outbreaks. African burial customs of washing dead bodies and transporting bodies without barrier precautions further transmit the disease in the community. 29, 58, 60, 61 Infected pigs can transmit REBOV to nonhuman primates via the airborne route and nonhuman primates can be infected experimentally by the inhalation of droplets (droplet size of 0.8e1.2 mm), although parenterally infected primates do not transmit the infection via the airborne route. 62e64 True airborne transmission of EBOV between humans has likewise not been documented. Up to 40% of patients in some EBOV outbreaks may have no known contact or exposure history, although it remains unclear whether this is because of fomites, true airborne transmission, or inadequate investigation. 57,58,61,65 Table 2 Outbreaks of human filovirus infection. 5, 68, 80, 176, 193, 194 Virus The ongoing EVD outbreak at the time of this writing is unique in two aspects: (1) its unprecedented scale and (2) its origination in West Africa (Guinea) rather than in central Africa. The first case occurred in Guinea in February 2014, and subsequently spread to the African countries of Liberia, Sierra Leone, Nigeria, Senegal, and Mali. In October 2014, the World Health Organization declared the epidemic over in Senegal and Nigeria. 66, 67 Further epidemiological investigations suggested the index case was probably a 2year-old child who died on December 6, 2013 in southern Guinea. 60 The infection was subsequently transmitted from the child to family members, a village midwife, and a healthcare worker; some of these patients later caused outbreaks in different areas of Guinea. Ebola virus disease has caused infection in 838 local healthcare workers of whom 495 (59%) workers died (as of January 7, 2015); four of these infected healthcare workers were citizens of the United States of America, Spain, and the United Kingdom who returned to their respective countries for further management. 68 34 On the other hand, asymptomatic infection was described in 1996, as evidenced by seroconversion in 46% of close contacts of patients, in two ZEBOV outbreaks in Gabon. 75 In 64% (7/11) of the seroconverted asymptomatic contacts, RT-PCR of the peripheral blood mononuclear cells was positive for the virus, and viremia persisted up to 2 weeks in some contacts. Another line of evidence for asymptomatic infections comes from seroprevalence studies in Africa, in which 2.2e15.3% of the surveyed population in central Africa was seropositive for EBOV with the seroprevalence consistently higher among forest-dwelling populations and hunters. 76e78 The incubation period of EVD varies from 2 days to 21 days (commonly, 6e10 days), but a recent analysis of the cases in the 1995 ZEBOV outbreak in Kitwit suggested that the mean incubation period was 12.7 days, and the maximum incubation period was up to 25 days. 79 A biphasic illness has been described with an apparent remission of 1e2 days in between. 5,6,80e82 The disease usually begins abruptly with nonspecific symptoms such as fever (93e95% of patients, ut infra), malaise (85e95%), headache (52e74%), sore throat, odynophagia or dysphagia (56e58%), hiccoughs (5e17%), and nonproductive cough (7e26%). Abdominal pain (62e68%) or nausea and vomiting (68e73%) often precede the onset of diarrhea (84e86%), usually 5 days after the onset of illness). The abdomen can be tender on palpation. In the absence of supportive therapy, diarrhea and vomiting may lead to fluid depletion and electrolyte disturbances such as hypokalemia. Other symptoms include arthralgia or myalgia (50e79%), chest pain (5e10%), and conjunctival injection (42e47%). A diffuse erythematous rash (14e16%) appears towards the end of the 1 st week which will later desquamate. The nonpruritic rash appears first on the trunk, and then spreads to the entire body with sparing of the face. Three early symptoms of bilateral conjunctival injection, rash, and sore throat are suggestive of EVD in the differential diagnosis. 82 After the appearance of the rash, patients may either gradually recover or, in severe cases, progress over 7e14 days to the full-blown hemorrhagic fever syndrome with petechiae (8%), gum bleeding (0e15%), melaena (8e16%), hemoptysis (0e11%), hematemesis (0e13%), epistaxis (0e2%), hematuria (7e16%), menorrhagia, bleeding at venipuncture sites (5e8%), and show features of disseminated intravascular coagulation. 82, 83 The typical hemorrhagic fever picture, however, occurs only in approximately 40% of the patients (range, 17e71%). 82, 84 Other manifestations in the late stage include evidence of multiorgan failure such as circulatory shock, obtundation, tachypnea, renal shutdown, convulsion, delirium, and coma. Fever is often absent at this stage. Death often occurs between Days 6 and 16, whereas patients who survive will show improvement around Days 6 to 11. 6 Intrauterine death is common in pregnant patients. Mortality among pregnant women is substantial but may not be significantly higher than for nonpregnant patients; and pregnant women do not have an increased susceptibility to the infection. 85, 86 Survivors tend to improve from the 2 nd week of illness. They make a slow recovery during which arthralgia (which could be asymmetric and migratory and often involves the large joints), uveitis, conjunctivitis, orchitis, parotitis, hearing loss, and tinnitus may occur. 80, 82 Chronic infection by filoviruses has not been documented, but male patients may shed the virus in the semen for 40e91 days after the onset of illness, and the transmission of MARV has occurred via sexual intercourse. 58, 59, 87, 88 Common laboratory findings include lymphopenia, thrombocytopenia, elevated aminotransferases, hyperproteinemia, proteinuria, and prolonged prothrombin and activated partial thromboplastin time. 6 With the progression of disease, evidence of disseminated intravascular coagulation and renal failure will appear. Disease progression is also associated with worsening lymphopenia and rising antigenemia. 89 Compared to survivors, patients with fatal EVD are more likely to have tachypnea. 82 Patients with disease also have a significantly higher level of viremia and a much weaker humoral immune response to the infection. 90 Significant differences in a number of cytokine and chemokine levels have also been detected between patients with nonfatal and fatal EVD; in particular, the levels of many proinflammatory cytokines and nitric oxide are higher in nonsurvivors (with the possible exception of BEBOV), whereas the level of T cells and CD8 þ T cells were lower. 25,89,91e94 A high viral load is of prognostic significance. In SEBOV FHF, patients with fatal cases had an average of 10 8 e10 9 (up to 10 10 ) copies of RNA/mL of serum, compared to the approximately 10 7 copies of RNA/mlL of serum in survivors. 90 Patients with MARV FHF likewise have high levels of viremia in blood with a median level of 4.1 Â 10 4 (range, 2.62 Â 10 2 e9.33 Â 10 8 )/mL of serum serum. 95 

There are no pathognomonic signs or symptoms in the early stages of EVD. The most useful history is epidemiological linkage to possible cases by travel history or by contact with known or suspected cases. Laboratory investigations are necessary to confirm the diagnosis. Other differential diagnoses (vide infra) should be excluded, as appropriate.

All clinical specimens must be handled with great care from their collection to transport and testing in the laboratories. Laboratory-acquired infection of EBOV has occurred via percutaneous exposures. 96 Marburgvirus retains its infectivity in dried blood for at least 5 days. 11 Filoviruses can be inactivated by heat [60 C for 60 minutes or 75 C for 30 minutes; or 60 C for 15 minutes in the presence of 0.2% (final concentration) sodium dodecyl sulfate or 0.1% (final concentration) Tween 20] or inactivated by 1% sodium deoxycholate solution, acetone, diethyl ether, 1% formalin, methanol, sodium hypochlorite, glutaraldehyde, 2% peracetic acid, phenolic disinfectants, and osmium tetroxide (used in fixation for electron microscopy). 11 Ultraviolet light is an effective means for surface disinfection. Depending on the type of specimen and testing methodology, treatment of the sample with either Triton X-100, Tween 20, sodium dodecyl sulfate, beta-propiolactone, chloramine B, or 3% acetic acid (pH 2.5) should be done before routine hematological, biochemical, and serological testing. 11 Heat inactivation is recommended for blood sodium, potassium, magnesium, urate, urea, creatinine, bilirubin, glucose, and C-reactive protein; however, other methods of inactivation would be necessary for calcium, phosphate, albumin, transaminases, gammaglutamyltransferase, and creatine kinase determination. 11 Standard virological techniques also apply to the diagnosis of FHF. These include viral culture, electron microscopy, serological tests using antigen or antibody detection, and nucleic acid amplification. 5, 97 Filoviruses can be cultivated from clinical specimens (especially blood and liver samples); however, because of the associated biohazards, a viral culture is notdand should not bedroutinely performed, except in facilities that can handle biosafety level 4 agents. Electron microscopy, which has excellent specificity because of the unique morphology of filoviruses, is also not routinely performed because of biosafety considerations, limited availability of electron microscope facilities in routine diagnostic settings, and the relatively high viral load necessary for visualization.

The detection antibodies [e.g., immunoglobulin M (IgM) or immunoglobulin G (IgG)] is commonly achieved using immunofluorescent assays and enzyme-linked immunoassay (ELISA) against recombinant NP, GP, VP40, VP35, or VP30 antigens. 97e99 The appearance of IgM and IgG antibodies occurs at approximately 2 days and 6e18 days, respectively, after the onset of illness. 6 Various antigen detection assays have been developed for the diagnosis of FHF and some have been used in field situations. The techniques include antigencapture ELISA, immunofluorescent assay, dot-immunobinding assay, immunofiltration assay with different genus-specific or species-specific reactivity towards common targets such NP, GP, and VP40 proteins. 97, 100, 101 A practical limitation of these serological assays is the limited availability of these tests in laboratories in nonendemic countries.

Nucleic acid amplification is the diagnostic test of choice because of its high sensitivity (especially in the early phase of illness); its ability to differentiate between different agents of viral hemorrhagic fever; and its relatively lower biohazard, if the viruses are appropriately inactivated; and because antigen and antibody assays are often unavailable in laboratories in nonendemic countries. When the viral load is determined by quantitative assays, prognostic information can also be obtained. The most commonly used test is RT-PCR. A reverse transcriptioneloop-mediated isothermal amplification assay has also been developed for EBOV and MARV. 102, 103 All diagnostic nucleic acid amplification tests must be adequately validated before being used clinically. If appropriately validated, the use of multiplex PCR/RT-PCR allows simultaneous detection of multiple pathogens that cause hemorrhagic fever. 104, 105 The provision of nucleic acid amplification tests should preferably be centralized in national or regional reference laboratories to ensure adequate biosafety containment and quality of results. The RNA of EBOV can be detected in the sera by RT-PCR 24e48 hours earlier than by antigen capture; in some studies, it is detectable on Day 1 of the illness. 6, 90 However, the viral load gradually reaches its peak at approximately 3 e7 days after the onset of the disease. 90 Retesting is therefore necessary if RT-PCR is initially negative but clinical suspicion is high, especially when the first sample was obtained within 3 days of the onset of disease. Blood is the most commonly used sample for RT-PCR. Oral fluid specimens can be a viable alternative to blood samples for RT-PCR in situations in which blood taking may be difficult or infeasible. 106 Common targets for nucleic acid amplification include the L, GP, and NP genes. 89, 90, 95, 107, 108 Clinical management and vaccine development Treatment of FHF is primarily supportive owing to the unavailability of approved, specific antiviral agents. Concurrent infections such as malaria or bacterial sepsis should be treated, as appropriate. Fluid and electrolyte replacement, blood product transfusion, renal replacement therapy, and ventilatory support such as extracorporeal membrane oxygenation should be administered, as necessary. 6, 109 Various experimental therapeutic approaches have been attempted in experimental animals or clinically; however, no randomized controlled trials prove their efficacy. Examples include recombinant inhibitor of factor VII (rNAPc2), recombinant human activated protein C, and interferon-beta. 110e112 As in cases of other severe viral infections, convalescent plasma from recovered patients has been used to treat FHF. This was deployed with apparent benefits in the 1995 EVD outbreak in Kitwit. 113 The World Health Organization (WHO) published a guideline on the collection and preparation of convalescent plasma for use in the outbreak situation; however, the WHO recognizes the uncertainties in the efficacy of this treatment. 114 Cocktails of monoclonal antibodies have similarly been used recently with some success in reducing the mortality of EBOV infection in nonhuman primates. These antibodies have been produced in plants and in mice. 115e117 Based on these studies, an optimized cocktail of plant-derived monoclonal antibodies, called the ZMapp, was produced; it protected 100% of rhesus macaques infected up to 5 days with EBOV. 118 These antibodies have been used experimentally for treating human EBOV patients in the 2014 West African outbreak, although the actual benefit to human EVD remains to be confirmed.

A second approach to the treatment of FHF lies in the development of specific antiviral agents. A current nucleotide analogue is favipiravir (T-705), which was developed and approved in Japan for the treatment of influenza. Favipiravir inhibits viral RNA-dependent RNA polymerase of the influenza virus. It was subsequently found to exhibit in vitro antiviral activities against certain other RNA viruses such as bunyaviruses, arenaviruses, flaviviruses, alphaviruses, norovirus, and EBOV. 119e123 Animal studies also demonstrate the efficacy of favipiravir in the treatment of Junín virus, arenavirus, and EBOV hemorrhagic fevers, and the drug was used to treat human EVD in the 2014 West African epidemic. 124e128 A dosing regimen of favipiravir for use in a clinical trial for the treatment of EVD has been published. 129 Another nucleotide analogue, brincidofovir (a lipid conjugate of cidofovir), was previously developed to treat infections due to DNA viruses such as adenoviruses, herpesviruses, and orthopoxviruses; the drug was granted Emergency Investigational New Drug Applications in October 2014 by the United States (US) Food and Drug Administration for evaluation in EVD treatment, and a clinical trial was started in January 2015 in Monrovia, Liberia. 130e132 The nucleoside analogue BCX4430 was recently shown to inhibit RNA polymerase of negative-and positive-sense RNA viruses via chain termination effects. 133 Its in vivo activity against MARV was demonstrated in guinea pigs and cynomolgus macaques. The development of BCX4430 for human clinical trials will require a long time.

Another approach involves the screening of currently available nonantimicrobials for their activities on filoviruses. Compounds such as selective estrogen receptor modulators (e.g., clomiphene, toremifene), amiodarone, dronedarone, and verapamil have antifilovirus activity in cell cultures and/or murine models. 134, 135 In addition, RNA interference using small interfering RNAs provide postexposure protection of animals infected with EBOV and MARV. 136e138 A third approach to the specific management of filoviral infections explores the potential of postexposure prophylaxis. Such regimens would benefit exposed healthcare workers and other social contacts, and laboratory staff experiencing accidental exposures. Protective immunity towards filoviruses does exist, as demonstrated in the possible benefits of convalescent plasma and animal studies, in which humoral immunity (i.e., IgG) protects against EBOV infection. 139 Animals studies also confirm that passive immunization by neutralizing monoclonal antibodies is protective in primates. 140 Previously examined filovirus vaccine candidates that elicit protective humoral immunity experimentally include EBOV-like particles containing GP, NP, and VP40; replication-deficient EBOV mutants that lack the VP30 gene; and EBOV GP-containing fragment or fusion protein. 141e144 A phase 1 clinical trial has tested DNA vaccines encoding the glycoproteins of EBOV and MARV. 145 One of the most promising vaccine candidates for filoviruses is the recombinant vesicular stomatitis virus-based vaccine system that expresses filoviral GP. This system elicits protective immunity against ZEBOV, SEBOV, BEBOV, and MARV; it also offers substantial postexposure prophylaxis in primate and murine models. 146e152 The vaccine was used for postexposure prophylaxis in a laboratory staff person who sustained a needle stick injury with ZEBOV in 2009. 153 A similar vaccine system used replication-defective recombinant adenovirus that expressed EBOV GP was protective in animal models. 154, 155 Phase 1 clinical trials of the vesicular stomatitis virus-based and adenovirus-based vaccines began in late 2014. 156 Ebola virus disease as a problem in nonendemic countries: issues on prevention and control

The containment of FHF outbreaks in endemic countries requires substantial resources in coordination between the public health system and other authorities of the countries, surveillance of the disease, education and engagement of local citizens, isolation and treatment facilities, and laboratory support. 157, 158 These requirements are often beyond the capability of endemic countries. Significant international assistance is usually needed to contain major outbreaks. The discussion on these public health issues is beyond the scope of this article. For health authorities in nonendemic countries, a preparedness plan for emerging infections is an indispensable component of the public health system. The development and adoption of preparedness and response plans for emerging infectious diseases are first fostered in anticipation of pandemic influenza. The outbreaks of severe acute respiratory syndrome (SARS), pandemic influenza A (i.e., H1N1), Middle East respiratory syndrome coronavirus (MERS-CoV), and, more recently, avian influenza A (i.e., H7N9) and EVD underscore the importance of such pre-emptive plans in preventing or mitigating the effects of disease transmission. 159, 160 The details may vary, depending on the nature of the pathogens; however, key components in public health response include risk assessment; communication and education; establishing a rapid response team and management team to coordinate responses between different government ministries; monitoring and surveillance; providing adequate facilities and supplies for quarantine and infection control; developing laboratory diagnostics; and where appropriate, antimicrobial and vaccination policies, and/or stockpiling. 159, 161 For clinicians in nonendemic countries, FHF will mostly be encountered in travelers returning from endemic areas. The 2003 SARS epidemic and 2009 influenza A (H1N1) pandemic demonstrated the efficiency of international traveldespecially air traveldin the global spread of infectious diseases. 162, 163 As a continent, Africa has a relatively small number of international travelers (only Oceania has a smaller number of international tourist arrivals), although the exportation of FHF to nonendemic countries is well documented in the present epidemic. 164 It is tempting to consider establishing travel restrictions to limit the spread of EVD outside of Africa; however, the actual benefit of such policies is limited. 165 At the time of this writing, the WHO has issued no travel restrictions to the affected countries. However, it is prudent to issue health warnings to potential visitors to affected countries. Pretravel education on transmission routes, precautionary measures, self-monitoring of signs and symptoms, and availability of medical care in destination countries should be provided. As in other subspecialties of travel medicine, the visiting friends and relatives (VFRs) are at particularly high risk of contracting travel-related infections. 166 Despite the fact that publicity and health alerts are often announced to the general public, VFRs do not always receive the necessary information on the risks because of cultural differences, language barriers, or different perceptions. Hence, efforts must be targeted to VFRs (especially African communities in this context) to reduce the risk of disease importation.

Remote infrared thermal scanners have been used as a means of fever screening at airports in some countries. The practice first gained popularity during the 2003 SARS epidemic, and was subsequently evaluated in the 2009 influenza A (H1N1) pandemic. 167e170 To a lesser extent, this method has also been used for the screening of other febrile illness such as dengue fever. 171 Infrared thermal scanning is relatively popular in Asian countries such as Taiwan, Japan, Korea, and Hong Kong, and it is usually used in conjunction with health questionnaires for self-reported symptoms such as fever and travel history. The tympanic temperature would be measured for suspected cases. The sensitivity, specificity, and positive predictive value of thermal scanning are affected by a variety of factors such as the instruments used, the threshold temperature, the part of the body being measured, the distance of the instruments from the individual, and the previous use of antipyretic agents. Patients in the incubation period of an infection obviously will not be detected by this screening method. Despite the relatively low sensitivity, specificity, and positive predictive values of infrared thermal scanning, some investigators consider it a useful adjunctive measure for border screening, although it cannot be relied on as the sole method for screening. 167e170 Contact tracing must be promptly initiated for any potential contacts of returned travelers diagnosed with a communicable infectious disease such as EVD. Detailed guidance on contact tracing for patients with EVD and other forms of viral hemorrhagic fevers have been published. 172, 173 All suspected contacts must undergo individual risk assessments, based on the travel history, the epidemic situation in the affected countries, and the nature of potential exposure before and during travel. 173 Detailed instructions and information must be provided to the contacts, who will then be monitored for fever and the development of symptoms. The monitoring may be performed in the community or within healthcare facilities, during which some limitations indor at least, advice againstdthe freedom to travel within the community or country may be necessary and interference of daily activities may be inevitable. 174 Close and empathetic liaison between the contacts and health departments is essential to ensure compliance with monitoring and to minimize psychological impacts. A preparedness plan for contact tracing, disease surveillance, clinical management, isolation precautions, and outbreak management must be in place to manage such incidents in nonendemic countries.

Hemorrhagic fever remains an uncommon cause of fever in returned travelers, although it is severe clinically and has substantial public health implications. The risk of FHF in returned travelers is low. Ten cases of Marburg hemorrhagic fever were reported from 1967 to 2012, and all patients had a travel history to Africa. 175 Cases of imported EVD (excluding the nonpathogenic REBOV) were described in South Africa in 1996 (ZEBOV) and in Switzerland in 1994 (TAFV). 176 Other causes of fever in such settings must be excluded by appropriate laboratory investigations. These include (depending on the itinerary and exposure history) other causes of fever with or without hemorrhagic presentations such as meningococcal infections, severe sepsis due to other bacterial infections (including rare infections such as anthrax and plague as guided by the clinical picture and exposure history), leptospirosis, typhoid and other causes of enteric fever, rickettsioses, malaria, trypanosomiasis, visceral leishmaniasis, dengue fever, and yellow fever. In particular, malaria (which is a very common treatable cause of fever in returned travelers and is endemic in sub-Saharan Africa) must be excluded by appropriate testing. Depending on the travel destination, other causes of viral hemorrhagic fever have to be considered such as Lassa fever, Hantavirus infection, Crimean-Congo hemorrhagic fever, and Rift Valley fever. The travel history should also include human contacts with sick individuals in the community (e.g., attending local funerals) or in healthcare facilities (as in the case of volunteer workers). 84 Another important exposure history is interaction with bats and other wild animals (especially primates). For example, a history of spelunking has resulted in FHF among local citizens and foreign visitors. Cases of Marburg hemorrhagic fever have occurred after exposure of visitors to bats in caves in Kenya and Uganda. 177, 178 When FHF is suspected based on travel and/or exposure histories, pre-emptive isolation is essential to minimize the risk of subsequent interpersonal spread, until the diagnosis is excluded. The routes of transmission of filoviruses are well documented. Transmission can be interrupted, provided that proper infection control and public health measures are implemented. Detailed infection control guidelines on caring for patients with FHF have been published. 57,179e182 In essence, the principles of isolation and use of personal protective equipment are not significantly different from standard precautions and transmissionbased precautions (i.e., contact, droplet, and airborne) that are universally practiced in healthcare facilities. However, numerous studies and reviews have confirmed that the compliance with the choice and use of personal protective equipment among healthcare workers are almost always suboptimal. 183e185 Essential factors that ensure the optimal implementation of infection control protocols are adequate training of healthcare workers on isolation procedures and on the appropriate use of personal protective equipment, preferably by interactive training with clear instructions; adequate manpower and organizational support; and the availability of timely and adequate guidance and support. 186e188 Such training should not be limited to staff working in clinical areas; it must also include other healthcare workers such as laboratory workers and paramedical personnel. The key elements of infection control consist of patient placement (e.g., isolation facilities), strict adherence to hand hygiene (e.g., the WHO's "five moments for hand hygiene"), proper use of personal protective equipment such as gloves (e.g., double gloves in special circumstances), waterproof gowns, respiratory protection (e.g., surgical masks, respirators during aerosol-generating procedures), eye protection, rubber boots, and safe handling of sharp objects. 55 Support staff engaged in environmental disinfection, funerals, and burial services must also be adequately trained on the proper use of personal protective equipment and chemical disinfectants, and on the handling of human remains to ensure adequate disinfection and minimize the risk of accidental exposure to the virus. 55, 189, 190 Conclusion Filoviral hemorrhagic fevers are uncommon, but they pose real clinical and public health threats to countries outside endemic areas. The routes of transmission, clinical manifestations, and infection control measures are well documented. Prevention of secondary transmission is possible, provided that cases are promptly identified, and standard isolation and precautionary measures are strictly followed. As in cases of pandemic influenza or other epidemic-prone infections, a preparedness plan is essential to cope with the importation of the diseases and limit their subsequent spread. To minimize the risk of disease importation, it is essential to have a concerted program to engage VFRs and other at-risk travelers by community health education and advisories. The current EVD outbreak provides an opportunity to evaluate new therapeutic and prophylactic strategies, whereas their actual value of these strategies in controlling the current and future epidemics require detailed clinical evaluations.

Ebola and Marburg haemorrhagic fever viruses: major scientific advances, but a relatively minor public health threat for Africa

Taxonomy of Viruses. Virus taxonomy: 2013 release

Discovery of an Ebolavirus-like filovirus in Europe

Ebolavirus and Marburgvirus: insight the Filoviridae family

Ebola and Marburg hemorrhagic fever

Ebola haemorrhagic fever

Filoviridae: Marburg and Ebola viruses

An introduction to Ebola: the virus and the disease

Vervet monkey disease: studies on some physical and chemical properties of the causative agent

Physicochemical inactivation of Lassa, Ebola, and Marburg viruses and effect on clinical laboratory analyses

A compendium of 40 years of epidemiological, clinical, and laboratory studies

Inactivation of Lassa, Marburg, and Ebola viruses by gamma irradiation

Evasion of interferon responses by Ebola and Marburg viruses

Antigenic subversion: a novel mechanism of host immune evasion by Ebola virus

The Ebola virus interferon antagonist VP24 directly binds STAT1 and has a novel, pyramidal fold

In silico-derived small molecules bind the filovirus VP35 protein and inhibit its polymerase cofactor activity

Development of RNA aptamers targeting Ebola virus VP35

How Ebola and Marburg viruses battle the immune system

Activation of triggering receptor expressed on myeloid cells-1 on human neutrophils by Marburg and Ebola viruses

Pathogenesis of filoviral haemorrhagic fevers

A compendium of 40 years of epidemiological, clinical, and laboratory studies

Hemorrhagic fever virus-induced changes in hemostasis and vascular biology

The contribution of the endothelium to the development of coagulation disorders that characterize Ebola hemorrhagic fever in primates

Host response dynamics following lethal infection of rhesus macaques with Zaire ebolavirus

Characterization of host immune responses in Ebola virus infections

Molecular determinants of Ebola virus virulence in mice

Antibodies are necessary for rVSV/ZEBOV-GPmediated protection against lethal Ebola virus challenge in nonhuman primates

Forty years of Marburg virus

Report of an International Commission: Ebola haemorrhagic fever in Zaïre

World Health Organization/International Study Team. Ebola haemorrhagic fever in Sudan

Ebola hemorrhagic fever associated with novel virus strain

World Health Organization. Ebola outbreak in Democratic Republic of Congo eupdate

Human infection due to Ebola virus, subtype Côte d'Ivoire: clinical and biologic presentation

WHO experts consultation on Ebola Reston pathogenicity in humans

Reston ebolavirus in humans and animals in the Philippines: a review

Discovery of swine as a host for the Reston ebolavirus

Fruit bats as reservoirs of Ebola virus

Experimental inoculation of plants and animals with Ebola virus

Isolation of genetically diverse Marburg viruses from Egyptian fruit bats

Large serological survey showing cocirculation of Ebola and Marburg viruses in Gabonese bat populations, and a high seroprevalence of both viruses in Rousettus aegyptiacus

Reston Ebolavirus antibodies in bats, the Philippines

Ebola virus antibodies in fruit bats

Serological evidence of ebolavirus infection in bats, China

Risk factors for Marburg hemorrhagic fever, Democratic Republic of the Congo

International Scientific and Technical Committee for Marburg Hemorrhagic Fever Control in the Democratic Republic of the Congo. Marburg hemorrhagic fever associated with multiple genetic lineages of virus

Human Ebola outbreak resulting from direct exposure to fruit bats in Luebo, Democratic Republic of Congo

Seasonal pulses of Marburg virus circulation in juvenile Rousettus aegyptiacus bats coincide with periods of increased risk of human infection

Multiple Ebola virus transmission events and rapid decline of central African wildlife

A serological survey of Ebola virus infection in central African nonhuman primates

Wild animal mortality monitoring and human Ebola outbreaks, Gabon and Republic of Congo

Replication, pathogenicity, shedding, and transmission of Zaïre ebolavirus in pigs

Review of Ebola virus infections in domestic animals

Ebola virus antibody prevalence in dogs and human risk

The natural history of Ebola virus in Africa

Ebola and Marburg virus disease epidemics: preparedness, alert, control, and evaluation

Ebola hemorrhagic fever transmission and risk factors of contacts

Ebola virus disease in southern Sudan: hospital dissemination and intrafamilial spread

Transmission of Ebola hemorrhagic fever: a study of risk factors in family members

Assessment of the risk of Ebola virus transmission from bodily fluids and fomites

Emergence of Zaïre Ebola virus disease in Guinea

Clinical manifestations and case management of Ebola haemorrhagic fever caused by a newly identified virus strain

Transmission of Ebola virus from pigs to nonhuman primates

Evaluation of transmission risks associated with in vivo replication of several high containment pathogens in a biosafety level 4 laboratory

Lethal experimental infections of rhesus monkeys by aerosolized Ebola virus

Ebola hemorrhagic fever, Kikwit, Democratic Republic of the Congo, 1995: risk factors for patients without a reported exposure

World Health Organization. The outbreak of Ebola virus disease in Senegal is over

World Health Organization. WHO declares end of Ebola outbreak in Nigeria

Ebola situation report

The basic reproductive number of Ebola and the effects of public health measures: the cases of Congo and Uganda

Understanding the dynamics of Ebola epidemics

WHO Ebola Response Team. Ebola virus disease in West Africadthe first 9 months of the epidemic and forward projections

Genomic surveillance elucidates Ebola virus origin and transmission during the 2014 outbreak

World Health Organization. WHO declares end of Ebola outbreak in the Democratic Republic of Congo

Democratic Republic of Congo: "classic" Ebola in a country experiencing its seventh outbreak

Human asymptomatic Ebola infection and strong inflammatory response

Antibody prevalence against haemorrhagic fever viruses in randomized representative Central African populations

High prevalence of both humoral and cellular immunity to Zaïre ebolavirus among rural populations in Gabon

Prevalence of IgG antibodies to Ebola virus in individuals during an Ebola outbreak, Democratic Republic of the Congo

Incubation period of Ebola hemorrhagic virus subtype Zaïre

Ebola haemorrhagic feverda review

Ebola hemorrhagic fever outbreaks in Gabon, 1994-1997: epidemiologic and health control issues

Ebola hemorrhagic fever in Kikwit, Democratic Republic of the Congo: clinical observations in 103 patients

A compendium of 40 years of epidemiological, clinical, and laboratory studies

A clinical guide to viral haemorrhagic fevers: Ebola, Marburg and Lassa

Ebola hemorrhagic fever and pregnancy

What obstetrician-gynecologists should know about Ebola: a perspective from the Centers for Disease Control and Prevention

Clinical, virologic, and immunologic follow-up of convalescent Ebola hemorrhagic fever patients and their household contacts, Kikwit, Democratic Republic of the Congo. Commission de Lutte contre les Epidémies à Kikwit

Spermatogenic transmission of the "Marburg virus". (Causes of "Marburg simian disease")

Analysis of human peripheral blood samples from fatal and nonfatal cases of Ebola (Sudan) hemorrhagic fever: cellular responses, virus load, and nitric oxide levels

Rapid diagnosis of Ebola hemorrhagic fever by reverse transcription-PCR in an outbreak setting and assessment of patient viral load as a predictor of outcome

Ebola hemorrhagic fever: novel biomarker correlates of clinical outcome

Human fatal Zaïre Ebola virus infection is associated with an aberrant innate immunity and with massive lymphocyte apoptosis

Cytokine and chemokine expression in humans infected with Sudan Ebola virus

Serology and cytokine profiles in patients infected with the newly discovered Bundibugyo ebolavirus

Viral load among patients infected with Marburgvirus in Angola

A case of Ebola virus infection

Filoviruses. a compendium of 40 years of epidemiological, clinical, and laboratory studies

ELISA for the detection of antibodies to Ebola viruses

Enzyme-linked immunosorbent assay for detection of filovirus species-specific antibodies

Development of an immunofiltrationbased antigen-detection assay for rapid diagnosis of Ebola virus infection

Enzyme immunosorbent assay for Ebola virus antigens in tissues of infected primates

Rapid and simple detection of Ebola virus by reverse transcription-loop-mediated isothermal amplification

Development and evaluation of a simple assay for Marburg virus detection using a reverse transcription-loop-mediated isothermal amplification method

Comprehensive multiplex one-step real-time TaqMan qRT-PCR assays for detection and quantification of hemorrhagic fever viruses

Simultaneous detection of CDC category "A" DNA and RNA bioterrorism agents by use of multiplex PCR & RT-PCR enzyme hybridization assays

Detection of Ebola virus in oral fluid specimens during outbreaks of Ebola virus hemorrhagic fever in the Republic of Congo

Detection and molecular characterization of Ebola viruses causing disease in human and nonhuman primates

Laboratory diagnosis of Ebola hemorrhagic fever during an outbreak in Yambio, Sudan

Clinical management of filovirus-infected patients

Treatment of Ebola virus infection with a recombinant inhibitor of factor VIIa/tissue factor: a study in rhesus monkeys

Interferon-beta therapy prolongs survival in rhesus macaque models of Ebola and Marburg hemorrhagic fever

Recombinant human activated protein C for the postexposure treatment of Ebola hemorrhagic fever

Treatment of Ebola hemorrhagic fever with blood transfusions from convalescent patients. International Scientific and Technical Committee

Use of convalescent whole blood or plasma collected from patients recovered from Ebola virus disease. Empirical treatment during outbreaks

Therapeutic intervention of Ebola virus infection in rhesus macaques with the MB-003 monoclonal antibody cocktail

Delayed treatment of Ebola virus infection with plant-derived monoclonal antibodies provides protection in rhesus macaques

Successful treatment of Ebola virus-infected cynomolgus macaques with monoclonal antibodies

Reversion of advanced Ebola virus disease in nonhuman primates with ZMapp

Favipiravir (T-705), a novel viral RNA polymerase inhibitor

Efficacy of favipiravir (T-705) and T-1106 pyrazine derivatives in phlebovirus disease models

T-705) inhibits in vitro norovirus replication

Treatment of late stage disease in a model of arenaviral hemorrhagic fever: T-705 efficacy and reduced toxicity suggests an alternative to ribavirin

T-705) protects against peracute Rift Valley fever virus infection and reduces delayed-onset neurologic disease observed with ribavirin treatment

T-705) inhibits Junín virus infection and reduces mortality in a guinea pig model of Argentine hemorrhagic fever

Effective oral favipiravir (T-705) therapy initiated after the onset of clinical disease in a model of arenavirus hemorrhagic fever

Successful treatment of advanced Ebola virus infection with T-705 (favipiravir) in a small animal model

Post-exposure efficacy of oral T-705 (Favipiravir) against inhalational Ebola virus infection in a mouse model

Favipiravir: a new medication for the ebola virus disease pandemic

Dose regimen of favipiravir for Ebola virus disease

Potential and emerging treatment options for Ebola virus disease

Chimerix announces emergency investigational new drug applications for brincidofovir authorized by FDA for patients with Ebola virus disease

Oxford University begins trial of possible Ebola treatment at MSF Treatment Centre in Liberia

Protection against filovirus diseases by a novel broad-spectrum nucleoside analogue BCX4430

FDA-approved selective estrogen receptor modulators inhibit Ebola virus infection

The clinically approved drugs amiodarone, dronedarone and verapamil inhibit filovirus cell entry

Postexposure protection of guinea pigs against a lethal ebola virus challenge is conferred by RNA interference

Postexposure protection of nonhuman primates against a lethal Ebola virus challenge with RNA interference: a proof-of-concept study

Protection against lethal Marburg virus infection mediated by lipid encapsulated small interfering RNA

Immune parameters correlate with protection against ebola virus infection in rodents and nonhuman primates

Protective efficacy of neutralizing monoclonal antibodies in a nonhuman primate model of Ebola hemorrhagic fever

Ebola virus-like particle-based vaccine protects nonhuman primates against lethal Ebola virus challenge

Replication-deficient ebolavirus as a vaccine candidate

Ebola virus glycoprotein Fc fusion protein confers protection against lethal challenge in vaccinated mice

A highly immunogenic fragment derived from Zaïre Ebola virus glycoprotein elicits effective neutralizing antibody

VRC 206 Study Team. Safety and immunogenicity of DNA vaccines encoding Ebolavirus and Marburgvirus wild-type glycoproteins in a phase I clinical trial

Live attenuated recombinant vaccine protects nonhuman primates against Ebola and Marburg viruses

Postexposure protection against Marburg haemorrhagic fever with recombinant vesicular stomatitis virus vectors in nonhuman primates: an efficacy assessment

Vesicular stomatitis virus-based vaccines protect nonhuman primates against aerosol challenge with Ebola and Marburg viruses

Recombinant vesicular stomatitis virus vector mediates postexposure protection against Sudan Ebola hemorrhagic fever in nonhuman primates

Vesicular stomatitis virus-based vaccines protect nonhuman primates against Bundibugyo ebolavirus

Immunization with vesicular stomatitis virus vaccine expressing the Ebola glycoprotein provides sustained long-term protection in rodents

Durability of a vesicular stomatitis virus-based Marburg virus vaccine in nonhuman primates

Management of accidental exposure to Ebola virus in the biosafety level 4 laboratory

VRC 205 Study Team. A replicationdefective recombinant Ad5 vaccine expressing Ebola virus GP is safe and immunogenic in healthy adults

Recombinant adenovirus serotype 26 (Ad26) and Ad35 vaccine vectors bypass immunity to Ad5 and protect nonhuman primates against ebolavirus challenge

World Health Organization. Ebola vaccines, therapies, and diagnostics

Ebola virus disease: consolidated preparedness checklist

Filoviruses. A compendium of 40 years of epidemiological, clinical, and laboratory studies

Taiwan faces challenges on the emerging avian influenza A (H7N9) virus in China

The emerging novel Middle East respiratory syndrome coronavirus: The "knowns" and "unknowns

Public health crisis preparedness and response in Korea

The aetiology, origins, and diagnosis of severe acute respiratory syndrome

Spread of a novel influenza A (H1N1) virus via global airline transportation

United Nations World Tourism Organization. UNWTO Tourism Highlights

Assessing the impact of travel restrictions on international spread of the 2014 West African Ebola epidemic

Visiting relatives and friends (VFR), pregnant, and other vulnerable travelers

Thermal image scanning for influenza border screening: results of an airport screening study

Fever screening and detection of febrile arrivals at an international airport in Korea: association among self-reported fever, infrared thermal camera scanning, and tympanic temperature

Investigation of febrile passengers detected by infrared thermal scanning at an international airport

Fever screening during the influenza (H1N1-2009) pandemic at Narita International Airport

Fever screening at airports and imported dengue

Contact tracing during an outbreak of Ebola virus disease

Guidance for contact tracing of cases of Lassa fever, Ebola or Marburg haemorrhagic fever on an airplane: results of a European expert consultation

Retrospective evaluation of control measures for contacts of patient with Marburg hemorrhagic fever

Marburg hemorrhagic fever in returning travellers: an overview aimed at clinicians

Principles and practice of travel medicine

Marburgvirus disease in Kenya

Imported case of Marburg hemorrhagic feverdColorado

Infection prevention and control guidance for care of patients in health-care settings, with focus on Ebola

Personal protective equipment in the context of filovirus disease outbreak response. Rapid advice guideline

Management of hazard group 4 viral haemorrhagic fevers and similar human infectious diseases of high consequence

European Network for Diagnostics of Imported Viral Diseases. Management and control of viral haemorrhagic fevers and other highly contagious viral pathogens

Canadian Nosocomial Infection Surveillance Program. Are health care workers protected? An observational study of selection and removal of personal protective equipment in Canadian acute care hospitals

Compliance with isolation precautions at a university hospital

A review of the evidence for suboptimal compliance of healthcare practitioners to standard/universal infection control precautions

SARS Hospital Investigation Team. Factors associated with critical-care healthcare workers' adherence to recommended barrier precautions during the Toronto severe acute respiratory syndrome outbreak

Behind the mask: determinants of nurse's adherence to facial protective equipment

Barriers to implementing infection prevention and control guidelines during crises: experiences of health care professionals

Guidance for safe handling of human remains of Ebola patients in U.S. hospitals and mortuaries

Supplementary guidance for handling of dead bodies of suspected/confirmed Ebola virus disease (EVD)

The Ebola virus VP35 protein functions as a type I IFN antagonist

Ebolavirus VP24 binding to karyopherins is required for inhibition of interferon signaling

Ebola virus disease

Centers for Disease Control and Prevention. Chronology of Marburg hemorrhagic fever outbreaks