SARS
Summary
Severe acute respiratory syndrome is an atypical pneumonia caused by SARS-CoV, a betacoronavirus that emerged in Guangdong, China in 2002 and spread internationally before being contained in 2003. It binds ACE2, had a case fatality rate near 10%, and has not circulated since.
Detail
SARS-CoV is an enveloped, positive-sense, single-stranded RNA coronavirus whose reservoir is horseshoe bats, with masked palm civets in live-animal markets acting as the intermediate host. Illness begins with fever, myalgia, and headache, and progresses after several days to dry cough and dyspnoea, with diffuse alveolar damage on histology; diarrhoea and lymphopenia are common and upper respiratory symptoms are conspicuously mild. A defining epidemiological feature is that viral shedding peaks late, after symptoms are established, which made symptom-based isolation and contact tracing effective and allowed global eradication of human transmission by mid-2003, with a total of about 8,000 cases. This contrasts sharply with SARS-CoV-2, which uses the same ACE2 receptor but sheds substantially before and without symptoms, making containment by isolation of symptomatic cases impossible. Superspreading events and nosocomial transmission to healthcare workers dominated SARS epidemiology.
Sources
- Levinson Medical Microbiology and Immunology
- Harrison's Principles of Internal Medicine
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