SARS is caused by a coronavirus, one of a group of viruses that are responsible for about one third of all cases of the common cold. The variety that causes SARS had not been previously identified, and may have been transmitted to humans from a civet species in whose blood the virus is also found. Civets are considered a delicacy in SE China, where the disease originated. Infection with SARS mainly occurs when a person in close contact with someone who has the disease is exposed to exhaled droplets. The spread of the disease has been controlled by isolating infected patients and quarantining those exposed to them.
The disease apparently first occurred in Nov., 2002, in Foshan, Guangdong prov., China, but provincial authorities withheld information about it, and when it spread to Beijing local authorities there acted similarly. In Feb., 2003, the World Health Organization first noted reports of cases of atypical pneumonia from China, but Chinese officials did not begin cooperating fully with international experts until April. SARS subsequently spread to some 30 countries on five continents, and affected the economies of China, Hong Kong, and Toronto, where cases were the highest; Taiwan and Singapore were also hard hit. The rapid international spread of the 2002-3 outbreak was facilitated by air travel and the lack of prompt, early information about SARS from Chinese officials.
See study by T. Abraham (2004).