Severe acute respiratory syndrome (SARS)

Severe acute respiratory syndrome (SARS) is a viral respiratory disease of zoonotic origin caused by the SARS coronavirus (SARS-CoV). Between November 2002 and July 2003, an outbreak of SARS in southern China caused an eventual 8,098 cases, resulting in 774 deaths reported in 37 countries, with the majority of cases in China and Hong Kong (9.6% fatality rate) according to the World Health Organization (WHO). No cases of SARS have been reported worldwide since 2004. In late 2017, Chinese scientists traced the virus through the intermediary of civets to cave-dwelling horseshoe bats in Yunnan province. Initial symptoms are flu-like and may include fever, muscle pain, lethargy symptoms, cough, sore throat, and other nonspecific symptoms. The only symptom common to all patients appears to be a fever above 38 °C (100 °F). SARS may eventually lead to shortness of breath and pneumonia; either direct viral pneumonia or secondary bacterial pneumonia. The average incubation period for SARS is 4–6 days, although rarely it could be as short as 1 day or as long as 14 days. The primary route of transmission for S.A.R.S is contact of the mucous membranes with respiratory droplets or fomites. Whilst diarrhoea is common in people with SARS, the fecal-oral route does not appear to be a common mode of transmission. The basic reproduction number of SARS, R0, ranges from 2 to 4 depending on different analyses. Control measures introduced in April 2003 reduced this down to 0.4. SARS may be suspected in a patient who has: For a case to be considered probable, a chest X-ray must be positive for atypical pneumonia or respiratory distress syndrome. The WHO has added the category of 'laboratory confirmed SARS' for patients who would otherwise be considered 'probable' but who have not yet had a positive chest X-ray changes, but have tested positive for SARS based on one of the approved tests (ELISA, immunofluorescence or PCR). The appearance of SARS in chest X-rays is not always uniform but generally appears as an abnormality with patchy infiltrates.