key: cord-0877267-h89s56z8
authors: Chan, Jasper F.W.; Li, Kenneth S.M.; To, Kelvin K.W.; Cheng, Vincent C.C.; Chen, Honglin; Yuen, Kwok-Yung
title: Is the discovery of the novel human betacoronavirus 2c EMC/2012 (HCoV-EMC) the beginning of another SARS-like pandemic?
date: 2012-10-13
journal: J Infect
DOI: 10.1016/j.jinf.2012.10.002
sha: e74846054350d79eb8dcc0e2f4f3dd7e0b444539
doc_id: 877267
cord_uid: h89s56z8

Fouchier et al. reported the isolation and genome sequencing of a novel coronavirus tentatively named “human betacoronavirus 2c EMC/2012 (HCoV-EMC)” from a Saudi patient presenting with pneumonia and renal failure in June 2012. Genome sequencing showed that this virus belongs to the group C species of the genus betacoronavirus and phylogenetically related to the bat coronaviruses HKU4 and HKU5 previously found in lesser bamboo bat and Japanese Pipistrelle bat of Hong Kong respectively. Another patient from Qatar with similar clinical presentation and positive RT-PCR test was reported in September 2012. We compare and contrast the clinical presentation, laboratory diagnosis and management of infection due to this novel coronavirus and that of SARS coronavirus despite the paucity of published information on the former. Since 70% of all emerging infectious pathogens came from animals, the emergence of this novel virus may represent another instance of interspecies jumping of betacoronavirus from animals to human similar to the group A coronavirus OC43 possibly from a bovine source in the 1890s and the group B SARS coronavirus in 2003 from bat to civet and human. Despite the apparently low transmissibility of the virus at this stage, research preparedness against another SARS-like pandemic is an important precautionary strategy.

Summary Fouchier et al. reported the isolation and genome sequencing of a novel coronavirus tentatively named "human betacoronavirus 2c EMC/2012 (HCoV-EMC)" from a Saudi patient presenting with pneumonia and renal failure in June 2012. Genome sequencing showed that this virus belongs to the group C species of the genus betacoronavirus and phylogenetically related to the bat coronaviruses HKU4 and HKU5 previously found in lesser bamboo bat and Japanese Pipistrelle bat of Hong Kong respectively. Another patient from Qatar with similar clinical presentation and positive RT-PCR test was reported in September 2012. We compare and contrast the clinical presentation, laboratory diagnosis and management of infection due to this novel coronavirus and that of SARS coronavirus despite the paucity of published information on the former. Since 70% of all emerging infectious pathogens came from animals, the emergence of this novel virus may represent another instance of interspecies jumping of betacoronavirus from animals to human similar to the group A coronavirus OC43 possibly from a bovine source in the 1890s and the group B SARS coronavirus in 2003 from bat to civet and human. Despite the apparently low transmissibility of the virus at this stage, research preparedness against another SARS-like pandemic is an important precautionary strategy. ª 2012 The British Infection Association. Published by Elsevier Ltd. All rights reserved.

In 2003, the world witnessed the first pandemic of the new millennium. Instead of the anticipated influenza virus, the pandemic was caused by, for the first time, a novel coronavirus which was subsequently named the severe acute respiratory syndrome (SARS) coronavirus (CoV). 1e6 Within a few months, the virus caused a total of 8422 cases of SARS with 916 deaths in over 30 countries among five continents, with a crude fatality rate of around 11%. 7 The outbreak had left a lasting impact not only in the lives of those who were infected, but also the frontline healthcare workers, public health officials, and even general public. To many, the slightest hint of the potential re-emergence of SARS would be the beginning of another nightmare. On 23 September 2012, less than a decade after the SARS pandemic, the World Health Organization (WHO) reported two cases of severe community-acquired pneumonia which bear significant reminisce with SARS (Table 1 ). 8e13 Subsequent laboratory tests revealed a novel human coronavirus, the human betacoronavirus 2c EMC/2012 (HCoV-EMC). 14, 15 The emergence of these two cases of HCoV-EMC infection at this stage may represent one of the four possible scenarios. Firstly, HCoV-EMC may be similar to the seasonal human coronavirus HKU1 which was detected in less than 5% of samples from those with respiratory tract infections while 22%e59.2% of the general population is seropositive due to mild or asymptomatic infections in the past. 16e22 Even human coronavirus HKU1 was occasionally associated with mortality in those with underlying multiple comorbidities who presented with acute communityacquired pneumonia. 23 Therefore these two severe cases of HCoV-EMC may just represent the tip of an iceberg due to another previously unknown seasonal coronavirus. Secondly, it may be analogous to the situation of avian influenza H5N1 in which there are occasional transmissions of the virus from poultry to humans manifesting with severe disease and a mortality of over 50%. 24e36 Thirdly, this is a rare instance of a few isolated zoonotic infections which are dead-ends. The fourth situation, the most dangerous one, is that this is the beginning of another SARS-like pandemic in which there will be increasing animal-to-human and subsequent human-to-human transmissions. When the suitable environmental conditions and opportunities for transmission associated with lapse in biosafety and infection control measures are present, the virus may cause an explosive outbreak as in the case of SARS. It would therefore be important to review the current knowledge on the clinical features, epidemiology, virology, and laboratory diagnosis of this novel coronavirus, and most importantly, to formulate possible treatment options and infection control measures based on comparisons made with other coronaviruses including SARS CoV.

There are four genera in the family Coronaviridae within the order Nidovirales (Fig. 1A) . 37 The genus alphacoronavirus contains the human coronavirus 229E and NL63 which are associated with common cold, and the genera gammacoronavirus and deltacoronavirus which contain viruses that affect only animals especially the avian species. The genus betacoronavirus contains four groups. Group A contains human coronavirus OC43, which is associated with respiratory tract infections. Group B contains SARS-CoV, which is associated with severe pneumonia. HCoV-EMC belongs to the group C betacoronavirus. Group D betacoronavirus contains the Rousettus bat coronavirus HKU9. Members of Coronaviridae are known causes of respiratory, intestinal, hepatic and neurological diseases of varying severity in humans and animals. Similar to other coronaviruses, HCoV-EMC is an enveloped positive-sense singlestranded RNA virus with a genome size of about 30 kb. It is classified as a group 2c coronavirus by previous nomenclature, and was named as such by the Erasmus Medical Center in Rotterdam, the Netherlands, which was the first institution to sequence the viral genome. It is most closely related to the bat coronaviruses HKU4 and HKU5 found in the lesser bamboo bats (Tylonycteris pachypus) ( Fig. 2A and B) and Japanese Pipistrelle bat (Pipistrellus abramus) ( Fig. 2C and D) respectively as shown in the phylogenetic tree (Fig. 1A) . 38, 39 As expected, their genome arrangements are also similar to those of the members of group C betacoronavirus but different from other groups. 40 The gene order from 5 0 to 3 0 is Orf1ab containing the highly conserved polymerase and helicase genes, followed by the highly variable gene encoding Spike, five other accessory proteins, and then the more conserved Envelope, Membrane and Nucleoprotein (Fig. 1B) . The polymerase gene (RdRp) of HCoV-EMC has 90e92% amino acid identity with that of bat coronaviruses HKU4 or 5 while its spike gene (S) has only 64e67% amino acid identity with that of bat coronaviruses HKU4 or 5. The environmental stability of the virus is not known at this stage but might be important in determining its potential for further dissemination. In the case of SARS CoV, the virus had a higher degree of stability in the environment than other human coronaviruses, and could survive for at least two to three days on dry surfaces at room temperature and two to four days in stool. 41, 42 Further studies should be conducted to obtain the key basic virological information including its life cycle and molecular evolution in order to understand its clinical and epidemiological significance.

The clinical presentation of both laboratory-confirmed cases of infection associated with HCoV-EMC is an acute severe community-acquired pneumonia with acute renal failure (Table 1 ). In case 2, a preceding period of mild respiratory symptoms of fever and rhinorrhoea (from 14 August 2012 to 21 August 2012) was followed by a period of clinical stability (from 21 August 2012 to 3 Sept 2012) prior to the re-emergence of symptoms including cough, arthralgia, myalgia, and deterioration with severe pneumonia with acute renal failure. It is currently unknown whether the initial mild symptoms were caused by this novel virus, or related to another mild viral infection as no microbiological diagnosis was made. Of note, some friends of case 2 who travelled on the same trip also developed the initial mild symptoms, but all recovered without subsequent deterioration. It remains to be seen whether this novel coronavirus can cause mild infections especially as specific virological diagnostic tests are not performed routinely in most places.

From the limited clinical information released up to this stage, their clinical presentation of HCoV-EMC infection is unusual among the human coronaviruses 229E, NL63, OC43, and HKU1 which cause predominantly an acute self-limited upper respiratory tract infection without renal failure. The only exception is SARS CoV which causes an acute 

Pi-BatCoV HKU5 Ty-BatCoV HKU4 community-or hospital-acquired pneumonia with rapid respiratory deterioration. Besides the presenting symptoms of fever, chills, myalgia, malaise, and nonproductive cough, clinical deteriorations typically occurred one week after the onset of symptoms in SARS and were usually accompanied by watery diarrhoea. 5,6,43e53 Physical findings were indiscriminative from other causes of atypical pneumonia. Common chest radiograph findings included ground-glass opacities, focal consolidations with a predilection for involvement of the periphery and subpleural regions of the lower zones, progressive involvement of bilateral lung fields, and spontaneous pneumomediastinum. 44,54e58 The most prominent histopathological features in SARS patients who died before and after the tenth day of symptom onset were acute diffuse alveolar damage with air space oedema, and mixture of acute changes with organizing phase of diffuse alveolar damage respectively. 59e61 Less commonly, haemophagocytosis in the alveolar exudates, thrombosis of venules, secondary bacterial and fungal pneumonia, 62 and systemic vasculitis involving the walls of small veins have also been reported. 63 Unfortunately, the postmortem histopathological findings in case 1 are not available for comparison at this stage. The other unusual clinical feature observed in both cases of infection associated with HCoV-EMC was the presence of acute renal failure. Acute renal failure with histological evidence of acute tubular necrosis was present in 6.9% of patients with SARS which is possibly due to hypoxic kidney damage, 64 and was a poor prognostic factor. 65 However, 28.8% of SARS patients' urine had viral load detectable by quantitative reverse transcription-polymerase chain reaction (RT-PCR) which correlated with abnormal urinalysis. 66 It would be important to know the relative contribution of the direct HCoV-EMC induced cytolysis and the indirect pneumonia-related hypoxic damage to the severity of the renal pathology. In broiler chickens suffering from infection by the avian nephropathogenic infectious bronchitis virus, severe renal swelling and accumulation of urate in the tubules were commonly seen. 67 Histological findings included lymphoplasmacytic interstitial nephritis with characteristic tubular epithelial degeneration and sloughing. Minimal respiratory involvement was noted with this nephropathogenic coronavirus. Important differential causes of viral pneumonia with acute renal failure which should be considered when the initial sepsis workup of a compatible case is unrevealing include hantaviruses, agents of viral haemorrhagic fever, and influenza viruses. Other extrapulmonary manifestations of SARS including lymphopenia, diarrhoea, hepatic dysfunction, diastolic cardiac impairment, pulmonary arterial thrombosis, bleeding diathesis, myositis, neuromuscular abnormalities, and epileptic fits should also be looked for in the two cases of HCoV-EMC infection. 43,68e74 Because of the lack of knowledge on the spectrum of disease severity, the WHO's interim case definitions for case finding may only be appropriate for notification but not for frontline clinical management and triage because the initial presentation may be a milder form of acute respiratory infection with or without subsequent deterioration (Table 2 ). In elderly and young children with SARS, atypical presentation with the absence of fever and respiratory symptoms, and mild form of infection were occasionally reported. 77e82 Furthermore, co-infection with other causative agents of community-acquired pneumonia may lead to a false sense of security when other agents of acute respiratory disease were found as in the case of SARS when co-infection by human metapneumovirus was reported in 12.5%e66.7% of such patients. 53, 83 Therefore, applying the WHO interim case definitions in the investigation of patients without individualized risk assessment may lead to a significant proportion of patients with atypical presentation, mild disease, or co-infections being missed. In order to better understand the full spectrum of clinical features, to promptly provide the necessary treatment, and to apply the appropriate infection control measures to stop further dissemination of this novel coronavirus, a working algorithm with less stringent criteria for investigation in areas where resources are available can be considered (Fig. 3) . In Hong Kong, we recommend to investigate patients based on an individualized risk assessment approach, in which immunocompetent adult patients who have travelled to or resided in an area where infection with HCoV-EMC has been reported, or who are close contact within the last 10 days before the onset of illness with a probable or confirmed case while the case was ill, and who present with fever and respiratory symptoms, should receive a baseline chest radiograph for assessment of lower respiratory tract involvement, urinalysis and renal function tests to detect renal impairment. In immunocompromised, elderly, and paediatric patients who may have atypical or mild forms of the infection, the decision for further investigations should be more liberal. not pathognomonic. Similar to SARS CoV, a positive viral culture from respiratory, faecal, urine, or tissue specimens, or a fourfold rise in the neutralizing antibody titre in serum samples taken at 14e21 days apart should be the most definitive evidence of infection. However, their uses during the acute stage of the illness are limited by the long turnaround time, absence of access to designated biosafety level 3 laboratories for viral culture, or the need for convalescent samples. HCoV-EMC can be cultured by Zaki et al. on monkey kidney cells such as the Vero and LLC-MK cell lines. 11 In both cases, the laboratory diagnosis was made by nucleic acid detection by a pancoronavirus RT-PCR followed by viral genome sequencing. The development of specific quantitative real-time RT-PCR, with a turnaround time of a few hours, is expected soon but the low number of cases will impede the validation of such tests. Taking the experience from SARS CoV diagnostics, two specific gene targets, namely the polymerase gene and the nucleoprotein gene, should be considered as they are both well conserved in coronaviruses and less subject to variation with different clinical strains. 84e93 However the use of the accessory protein gene sequence upstream the Envelope gene (E) present only in HCoV-EMC was reported to be highly specific. 14 The nucleoprotein gene has the theoretical advantage of being more sensitive as its subgenomic RNA copy number is more abundant in infected cells, but clinical studies with SARS CoV did not definitively prove this advantage. Since the timing of the peak viral load of HCoV-EMC has not been determined, repeating the test in suspected cases with an initial negative result is necessary to avoid a false-negative result because the viral load of SARS CoV in nasopharyngeal aspirate (NPA) peaked at day 10 of symptom onset. 44, 84 Since the implications of a positive case are significant, positive test results from a single sample should be confirmed by a second test which detects a different region of the viral genome on the same sample in order to avoid falsepositive results due to amplicon carryover.

As the two cases both presented with severe pneumonia with lower respiratory tract involvement, lower tract specimens including sputum, bronchoalveolar lavage, endotracheal aspirate, and even lung tissue as in case 1, are the preferred specimen types to be collected and put into viral transport medium. However, in suspected cases where only upper respiratory tract involvement is clinically apparent, NPA, nasopharyngeal swab, throat swab and/or expectorated sputum should be obtained, and if initially negative, should be repeated with deterioration of symptoms and at day 7 to day 10 of symptom onset (Fig. 3) . As in the case of SARS and other coronaviruses, feces, 66, 94 urine, 64, 66 and sera 95 might be useful and should be collected for further testing as clinically indicated.

Besides RT-PCR, serum antigen detection with monoclonal antibodies or monospecific polyclonal antibody Any person with positive laboratory confirmation of infection with human betacoronavirus 2c EMC/2012 Closed contact 1. Anyone who provided care for the patient including a healthcare worker or family member, or had other similarly close physical contact; OR 2. Anyone who stayed at the same place (e.g.: lived with, visited) as a probable or confirmed case while the case was symptomatic Closed contacts who developed symptoms within the first 10 days after the last contact should be investigated From date of illness onset in index case and throughout their symptomatic period.

1. Health and social care workers: provided direct care or examination of a symptomatic confirmed case or within close vicinity of an aerosol generating procedure (<3 feet) AND not wearing full PPE at the time (correctly fitted high filtration mask, gown, gloves, and eye protection) 2. Household: prolonged face-to-face contact (>15 min) with the confirmed case(s) any time during the illness after onset in a household setting 3. Other close contact: prolonged face-to-face contact (>15 min) with a confirmed case in any other enclosed setting and not wearing a mask (e.g.: school, visitor to the hospital to the bed side) ARDS, acute respiratory distress syndrome; PPE, personal protective equipment.

Is discovery of HCoV-EMC the beginning of another SARS-like pandemic?

against the viral N protein was also shown to be a sensitive and specific test in the sero-diagnosis of SARS before the onset of neutralizing antibody response, 96e98 and might also be useful for infections associated with HCoV-EMC especially in areas where RT-PCR is not available. As the spectrum of clinical manifestations, epidemiology, and potential for further dissemination of this new disease are still poorly understood, antibody detection assays would be useful for seroepidemiological studies which would be highly useful in determining the exact situation and in planning of the relevant infection control strategies to contain the infection at an early stage.

The information on the epidemiology of infections associated with HCoV-EMC is mainly derived from the sequence of important events which is summarized in Table 1 . The most important epidemiological linkage at present seems to be the travelling to or the residence in areas where the infection has been reported, namely Qatar and the Kingdom of Saudi Arabia, in the preceding 10 days prior to the onset of illness. Case 2 had history of contact with camels and sheep. 10 Given the close phylogenetic relationships between HCoV-EMC and the bat coronaviruses HKU4 and HKU5 (Fig. 1A) , our speculation is that wild animals including bat may serve as the natural reservoir of many group B or C betacoronaviruses which jump into one or more intermediate hosts of food or game animals dwelling closely to human as in the case of infection due to SARS CoV (civet), Hendra (horses), Nipah (swine), and Ebola (primates) viruses. 99, 100 While pipistrelles, the natural reservoir of bat coronavirus HKU5, can be found in the Kingdom of Saudi Arabia, they are also seen in many other parts of the world. One possible reason why cases of infection associated with HCoV-EMC have not been reported in other areas may be explained by drawing an analogy to SARS CoV, whose transmission from the horseshoe bat (Rhinolophus sp.) to human was enhanced by intermediate animal hosts in palm civets and raccoon dogs. In Hong Kong, the regular surveillance of coronaviruses in patients' specimens or non-bat animal specimens in the past 5 years did not reveal a single case of infection by group C betacoronaviruses using consensus coronavirus primers and amplicon sequencing. 101 This might be related to the absence of the necessary intermediate hosts for amplifying the novel virus in our locality and the high level of biosecurity measures adopted at our farms and markets. Further studies are required to prove these postulations concerning animal-to-human transmission. In contrast to SARS, person-to-person transmission has so far not been observed in infections associated with HCoV-EMC. In case 2, no clinically apparent infection was seen in the healthcare workers and personnel of the medical escort company involved in the care and transfer of the patient from Qatar to the United Kingdom. Furthermore, the two confirmed cases were separated by three months temporally, and had no specific epidemiological linkage except for both having been in the Kingdom of Saudi Arabia prior to the onset of illness. There have been no further cases reported which might signify the absence of ongoing transmission in the community. However, if the outbreak of severe respiratory illness that occurred in a Jordanian hospital in April 2012, which involved a total of 11 people with eight of them being healthcare workers and one fatal case, was subsequently confirmed to be associated with HCoV-EMC, then person-toperson transmission, and particularly nosocomial transmission, would be possible (Table 1 ). In the case of SARS, personto-person transmission by direct or indirect contact of the mucosae with infectious respiratory droplets or fomites was considered to be the primary mode of spread, although airborne transmission under special circumstances has been reported. 102 Nosocomial transmission, facilitated by the use of nebulizers, suction, intubation, bronchoscopy, and cardiopulmonary resuscitation, was also well documented. 49, 103, 104 Importantly, unlike those with influenza, patients with SARS were most infectious on or after the fifth day after the onset of symptoms, and the viral load in nasopharyngeal secretions usually peaked on the tenth day. 44 Therefore, if the novel virus was truly capable of causing person-to-person spread, the optimal infection control strategies might need to be further reviewed. As the Hajj is approaching, recommendations on whether travel restrictions or additional infection control measures are required are urgently needed. It would be disastrous if the phenomenon of super-spreading events observed in SARS was also encountered in infections associated with HCoV-EMC. An example was the large community outbreak that occurred in Amoy Garden of Hong Kong in which dried U traps of sewage drains facilitated the contaminated aerosols generated in toilets by exhaust fans to ascend the light well connecting different floors and resulted in a massive outbreak affecting hundreds of residents. 105, 106 In terms of the hosts at risk of developing severe disease, no conclusion could be made at present. Both patients were reported to be free of chronic medical conditions prior to the infection. 107 Another poorly defined characteristic of the infections associated with the novel virus is the incubation period. Neither case gave an accurate account of the incubation period prior to the onset of symptoms as they were both considered to be sporadic cases. In general, the incubation period of human non-SARS coronaviruses is 2e5 days and that of SARS CoV is 2e14 days. 108,109 A well documented incubation period of this novel infection is critical for setting up the appropriate case definition for case finding, optimizing the timing of laboratory tests and number of tests required, and deciding on the necessary periods of medical surveillance and quarantine required for contact and confirmed cases respectively.

There is no proven effective antiviral agent against coronaviruses including SARS and HCoV-EMC. 3, 110 No animal model for satisfying Koch's postulates or for testing antiviral treatment or immunization is yet reported for HCoV-EMC. Clinical management is therefore mainly supportive, with particular emphasis on organ support for respiratory and renal failure. The recent advances made in the use of extracorporeal membrane oxygenation (ECMO) in the intensive care unit has been shown to improve survival rates to up to 50e70% in cases of acute respiratory failure. 111e114 As for renal failure, continuous venousevenous haemofiltration is commonly used in the intensive care unit with the aim of tiding the patient over the initial critical stage. Broad-spectrum antimicrobial coverage against typical and atypical agents of severe community-acquired pneumonia, such as a regimen consisting of a b-lactam, a macrolide, and an antiviral against influenza, should be instituted while awaiting the laboratory diagnosis. The antimicrobial treatment should be stopped when the diagnosis of HCoV-EMC associated pneumonia is made, unless in situations where nosocomial infections or immunosuppressive states coexist. 115 Specific antiviral agents including interferons (interferon-alfacon-1), ribavirin, and lopinavir-ritonavir with or without high-dose corticosteroid have been used in patients with SARS. 3 But their use was limited by a lack of evidence from randomized control trials and their potential side effects especially for ribavirin and steroid. Many other agents have shown in-vitro activities against SARS CoV, and included protease inhibitors such as nelfinavir and others, angiotensin-converting enzyme 2 analogues, helicase inhibitors and nucleoside analogues. However, their in-vivo activity and clinical utility for SARS and other coronaviruses remain elusive. 3 Corticosteroid should no longer be considered since patients with severe pneumonia and respiratory failure can be supported by ECMO till the cytokine storm is over.

Immunomodulating therapy with IgM-enriched immunoglobulin or convalescent plasma with neutralizing antibodies has been used in a small number of patients with SARS. 116e119 The data generated from these studies were limited by the small number of patients involved and the lack of randomized control trials conducted. Convalescent plasma is relatively free of side effect and might be considered should the novel virus continue to cause severe infections in a larger number of patients. However, if there were only a few convalescent patients, the preparation of convalescent plasma would not be feasible.

There is currently no specific international guideline for the infection control of HCoV-EMC. The WHO recommends strategies discussed in the WHO interim guideline for "infection prevention and control of epidemic-and pandemic-prone acute respiratory diseases in heath care". 120 These include the practice of Standard, Contact, and Airborne Precautions before the route of transmission is better defined. The HPA of the United Kingdom recommends a similarly stringent approach. 76 Besides these recommendations, a second virological test should be considered as the patient deteriorates or at day 7 to day 10 of symptom onset in symptomatic contacts who have an initial negative test result because the viral load may peak at day 10 as in the case of SARS CoV. While there is no travel restrictions imposed at present, the subsequent development of events associated with HCoV-EMC must be closely monitored especially as the Hajj is approaching. There is no recommendation on the infection control measures regarding animal contact. Simple personal hygienic measures such as hand hygiene after contact with animals and their excreta should be taken.

One of the major reasons why the SARS CoV successfully caused a devastating pandemic was the lack of anticipation by the global health community. Although the currently available information about HCoV-EMC seems to suggest that it has a lower transmissibility than that of SARS CoV, many important epidemiological, clinical and scientific questions remain unresolved. Healthcare authorities should not discard the potential of this novel virus to cause another SARS-like pandemic before such answers are available. While over-reactions are unnecessary, appropriate preparations and collaborations by international and local health agencies are important.

Koch's postulates fulfilled for SARS virus

The aetiology of SARS: Koch's postulates fulfilled

Severe acute respiratory syndrome coronavirus as an agent of emerging and reemerging infection

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

A cluster of cases of severe acute respiratory syndrome in Hong Kong

Coronavirus as a possible cause of severe acute respiratory syndrome

summary table of SARS cases by country

Global alert and response (GAR): novel coronavirus infection in the United Kingdom

Severe respiratory illness caused by a novel coronavirus

The United Kingdom public health response to an

Novel coronavirus e Saudi Arabia: human isolate

Rapid risk assessment: severe respiratory disease associated with a novel coronavirus

Communicable disease threats report (week 18

Detection of a novel human coronavirus by real-time reverse-transcription polymerase chain reaction

Partial genetic sequence information for scientists about the novel coronavirus

Characterization and complete genome sequence of a novel coronavirus, coronavirus HKU1, from patients with pneumonia

Phylogenetic and recombination analysis of coronavirus HKU1, a novel coronavirus from patients with pneumonia

Coronavirus genomics and bioinformatics analysis

Clinical features and molecular epidemiology of coronavirus-HKU1-associated community-acquired pneumonia

Epidemiology of coronavirusassociated respiratory tract infections and the role of rapid diagnostic tests: a prospective study

Coronavirus HKU1 and other coronavirus infections in Hong Kong

Development of a nucleocapsid-based human coronavirus immunoassay and estimates of individuals exposed to coronavirus in a U.S. metropolitan population

Clinical and molecular epidemiological features of coronavirus HKU1-associated community-acquired pneumonia

Clinical features and rapid viral diagnosis of human disease associated with avian influenza A H5N1 virus

Human infection by avian influenza A H5N1

Re-emergence of fatal human influenza A subtype H5N1 disease

H5N1 influenza: a protean pandemic threat

Avian influenza virus infections in humans

Avian influenza A/H5N1 virus: management in human and bird

Infectious diseases emerging from Chinese wet-markets: zoonotic origins of severe respiratory viral infections

Characterization of H9 subtype influenza viruses from the ducks of southern China: a candidate for the next influenza pandemic in humans?

Genesis of a highly pathogenic and potentially pandemic H5N1 influenza virus in eastern Asia

Establishment of multiple sublineages of H5N1 influenza virus in Asia: implications for pandemic control

Avian influenza A (H5N1) infection in a patient in China

Systemic infection of avian influenza A virus H5N1 subtype in humans

Avian influenza A (H5N1) infection in humans

Coronavirus diversity, phylogeny and interspecies jumping

Molecular diversity of coronaviruses in bats

Severe acute respiratory syndrome coronavirus-like virus in Chinese horseshoe bats

Comparative analysis of twelve genomes of three novel group 2c and group 2d coronaviruses reveals unique group and subgroup features

Stability of SARS coronavirus in human specimens and environment and its sensitivity to heating and UV irradiation

Stability and inactivation of SARS coronavirus

Viral replication in the nasopharynx is associated with diarrhea in patients with severe acute respiratory syndrome

Clinical progression and viral load in a community outbreak of coronavirus-associated SARS pneumonia: a prospective study

Clinical course and management of SARS in health care workers in Toronto: a case series

Clinical features and short-term outcomes of 144 patients with SARS in the greater Toronto area

Severe acute respiratory syndrome-associated coronavirus infection

Severe acute respiratory syndrome (SARS) in Singapore: clinical features of index patient and initial contacts

A major outbreak of severe acute respiratory syndrome in Hong Kong

Evaluation of WHO criteria for identifying patients with severe acute respiratory syndrome out of hospital: prospective observational study

The severe acute respiratory syndrome

Description and clinical treatment of an early outbreak of severe acute respiratory syndrome (SARS) in Guangzhou, PR China

Identification of severe acute respiratory syndrome in Canada

Severe acute respiratory syndrome: radiographic review of 40 probable cases in Toronto

Radiographic appearance and clinical outcome correlates in 26 patients with severe acute respiratory syndrome

Severe acute respiratory syndrome: quantitative assessment from chest radiographs with clinical and prognostic correlation

Severe acute respiratory syndrome: radiographic appearances and pattern of progression in 138 patients

Spontaneous pneumomediastinum in patients with severe acute respiratory syndrome

Lung pathology of severe acute respiratory syndrome (SARS): a study of 8 autopsy cases from Singapore

Lung pathology of fatal severe acute respiratory syndrome

Pulmonary pathology of severe acute respiratory syndrome in Toronto

Fatal aspergillosis in a patient with SARS who was treated with corticosteroids

The clinical pathology of severe acute respiratory syndrome (SARS): a report from China

Acute renal impairment in coronavirus-associated severe acute respiratory syndrome

Renal hypouricemia is an ominous sign in patients with severe acute respiratory syndrome

Viral loads in clinical specimens and SARS manifestations

Nephropathogenic infectious bronchitis in Pennsylvania chickens 1997e2000

SARS-associated viral hepatitis caused by a novel coronavirus: report of three cases

Possible central nervous system infection by SARS coronavirus

Left ventricular performance in patients with severe acute respiratory syndrome: a 30-day echocardiographic follow-up study

Pulmonary artery thrombosis in a patient with severe acute respiratory syndrome

Neuromuscular disorders in severe acute respiratory syndrome

Rhabdomyolysis associated with probable SARS

Haemorrhagic-fever-like changes and normal chest radiograph in a doctor with SARS

Global alert and response (GAR): revised interim case definitiondnovel coronavirus. Geneva, Switzerland: World Health Organization

Infection control advice e novel coronavirus cases. London: HPA

Outbreak of severe acute respiratory syndrome in a tertiary hospital in Singapore, linked to an index patient with atypical presentation: epidemiological study

Severe acute respiratory syndrome (SARS) in a geriatric patient with a hip fracture. A case report

Children hospitalized with severe acute respiratory syndrome-related illness in Toronto

Clinical presentations and outcome of severe acute respiratory syndrome in children

Severe acute respiratory syndrome can be mild in children

Relative rates of non-pneumonic SARS coronavirus infection and SARS coronavirus pneumonia

Human metapneumovirus detection in patients with severe acute respiratory syndrome

Detection of SARS coronavirus in patients with suspected SARS

Early diagnosis of SARS coronavirus infection by real time RT-PCR

Detection of SARS coronavirus in patients with severe acute respiratory syndrome by conventional and real-time quantitative reverse transcription-PCR assays

A one step quantitative RT-PCR for detection of SARS coronavirus with an internal control for PCR inhibitors

Viral shedding patterns of coronavirus in patients with probable severe acute respiratory syndrome

Reverse transcriptase PCR diagnostic assay for the coronavirus associated with severe acute respiratory syndrome

Detection of SARS-associated coronavirus in throat wash and saliva in early diagnosis

Serologic and molecular biologic methods for SARS-associated coronavirus infection

Evaluation of reverse transcription-PCR assays for rapid diagnosis of severe acute respiratory syndrome associated with a novel coronavirus

Detection of human coronaviruses in children with acute gastroenteritis

Detection of SARS coronavirus in plasma by real-time RT-PCR

Detection of specific antibodies to severe acute respiratory syndrome (SARS) coronavirus nucleocapsid protein for serodiagnosis of SARS coronavirus pneumonia

Nucleocapsid protein as early diagnostic marker for SARS

Sensitive and specific monoclonal antibody-based capture enzyme immunoassay for detection of nucleocapsid antigen in sera from patients with severe acute respiratory syndrome

Fruit bats as reservoirs of Ebola virus

Bats as a continuing source of emerging infections in humans

Wild animal surveillance for coronavirus HKU1 and potential variants of other coronaviruses

Possible SARS coronavirus transmission during cardiopulmonary resuscitation

Investigation of a nosocomial outbreak of severe acute respiratory syndrome (SARS) in Toronto, Canada

Viral load distribution in SARS outbreak

Evidence of airborne transmission of the severe acute respiratory syndrome virus

Morbidity and mortality weekly report (MMWR) e severe respiratory illness associated with a novel coronavirus e Saudi Arabia and Qatar

Incubation periods of acute respiratory viral infections: a systematic review

Epidemiologic linkage and public health implication of a cluster of severe acute respiratory syndrome in an extended family

Medical treatment of viral pneumonia including SARS in immunocompetent adult

Extracorporeal membrane oxygenation for adult respiratory failure

High survival rate in 122 ARDS patients managed according to a clinical algorithm including extracorporeal membrane oxygenation

Extracorporeal life support for severe acute respiratory distress syndrome in adults

Extracorporeal membrane oxygenation in adults with severe respiratory failure: a multi-center database

Development of a standard treatment protocol for severe acute respiratory syndrome

Treatment of severe acute respiratory syndrome with convalescent plasma

Experience of using convalescent plasma for severe acute respiratory syndrome among healthcare workers in a Taiwan hospital

Use of convalescent plasma therapy in SARS patients in Hong Kong

Pentaglobin in steroid-resistant severe acute respiratory syndrome

Infection prevention and control of epidemic-and pandemic-prone acute respiratory diseases in health care

We thanked Mr. C.T. Shek and the Agriculture, Fishery and Conservation Department for the photo in Fig. 2