Severe Acute Respiratory Syndrome (SARS)

Severe acute respiratory syndrome (SARS) is a new human disease caused by an animal coronavirus that adapted to efficient human-to-human transmission. The disease first emerged in November 2002 in Guangdong Province, China and spread globally within months. The SARS coronavirus (SARS CoV) affects multiple organ systems with severe viral pneumonia as its main clinical manifestation but with diarrhea, lymphopenia, and mild liver dysfunction being common extra-pulmonary manifestations. Increasing age and the presence of underlying respiratory diseases worsens the prognosis. Unlike other respiratory viral infections, transmission of SARS was less frequent in the first 5 days of illness and correlated with low viral load in the upper respiratory tract at this stage of the illness. This fortuitous feature of the disease allowed the public health measures of case detection and patient isolation to interrupt virus transmission in the community and abort the SARS outbreak. Bats are a reservoir of a virus closely related to SARS CoV and this may be the likely precursor from which the human-adapted SARS CoV emerged. Small mammals such as ‘civet-cats’ (Paguma larvata) within live animal markets in southern China serve as amplifiers of infection and these markets were the likely interface where zoonotic transmission occurred. The viral spike protein is necessary and sufficient for inducing protective antibody responses and has been a key target in the development of candidate vaccines.