The Severe Acute Respiratory Syndrome

Authors: Joseph S.M. Peiris, M.D., D.Phil., Kwok Y. Yuen, M.D., Albert D.M.E. Osterhaus, Ph.D., and Klaus Stöhr, Ph.D.

The severe acute respiratory syndrome (SARS) is responsible for the first pandemic of the 21st century. Within months after its emergence in Guangdong Province in mainland China, it had affected more than 8000 patients and caused 774 deaths in 26 countries on five continents. It illustrated dramatically the potential of air travel and globalization for the dissemination of an emerging infectious disease and highlighted the need for a coordinated global response to contain such disease threats. We review the cause, epidemiology, and clinical features of the disease.


An unusual atypical pneumonia emerged in Foshan, Guangdong Province, mainland China, in November 2002.1,2 In February and March 2003, the disease spread to Hong Kong and then to Vietnam, Singapore, Canada, and elsewhere (Table 1).3,4 The new disease was named the severe acute respiratory syndrome (SARS), and a preliminary case definition was established.4 A novel coronavirus (SARS-CoV) was identified as the causative agent.5-10 Coronaviruses are a family of enveloped, single-stranded–RNA viruses causing disease in humans and animals, but the other known coronaviruses that affect humans cause only the common cold.

The presence of SARS-CoV has been demonstrated by reverse-trancriptase polymerase chain reaction (RT-PCR) and the isolation of the virus from respiratory secretions, feces, urine, and tissue specimens from lung biopsy,11,12 indicating that the infection is not confined to the respiratory tract. The experimental infection of cynomolgus macaques with SARS-CoV produced a pneumonia that was pathologically similar to SARS in humans.8,9 Other pathogens, including human metapneumovirus13,14 and chlamydia,7,15 have been detected together with SARS-CoV in some patients with SARS, but they have not been found consistently.5,9 The experimental infection of macaques with human metapneumovirus did not lead to a SARS-like disease, and coinfection of macaques with human metapneumovirus and SARS-CoV did not enhance the pathogenicity of the SARS-CoV in this animal model.8 Thus, all the information that is available to date suggests that SARS-CoV is necessary and sufficient for the causation of SARS in humans, but it remains to be determined whether microbial or other cofactors enhance the severity or transmissibility of the disease. The complete genetic sequence of the SARS-CoV genome was determined, and it provided confirmation that SARS-CoV belongs to a new group within the coronavirus family.

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