Severe acute respiratory syndrome (SARS)

Severe acute respiratory syndrome (SARS) is a newly recognized illness that appears to be caused by a previously unknown virus belonging to the coronavirus family. The first known outbreak occurred in Guangdong Province in southern China in November 2002, and ultimately led to outbreaks in Hong Kong, Taiwan, Singapore, Viet Nam, and Toronto (Canada). Worldwide, more than 8000 cases and 800 deaths were reported. On July 5, 2003, the World Health Organization announced that the last chain of transmission had been been broken and the outbreak appeared to be over. Four more cases were reported from mainland China in December 2003-January 2004, and an additional eight cases in April 2004. Several other cases have been caused by laboratory exposure to the SARS virus. However, there is no evidence at present that the virus has re-entered the general population.

The incubation period for SARS usually ranges from 2-10 days (median 5 days). The first symptom is usually fever, often accompanied by chills, headache, body aches, and malaise. This is typically followed by dry cough and difficulty breathing, at times severe enough to require intubation and mechanical ventilation. The most recent analysis indicates that the overall fatality rate is approximately 15%, ranging from less than 1% in those younger than 25 years old to greater than 50% in those aged 65 years or older.

Much is still unknown concerning the mode of transmission. The overwhelming majority of the initial cases occurred in health care workers and in family members or other close contacts of those with the disease. This implied that intimate exposure to secretions from an infected person was necessary to become infected. However, a large number of cases were subsequently reported from a housing estate in Hong Kong, probably caused by contamination of the sewage system by infected fecal material from a man who had SARS and diarrhea. Recent studies have shown that the SARS virus may survive in fecal material for up to four days. Also, the virus may survive for 36 hours on a plastered wall or a formica surface, for 72 hours on a plastic surface or stainless steel, and for 96 hours on a glass slide, raising the possibility that SARS may be acquired from inanimate objects, though this remains unproven.

No travel restrictions are recommended at this time. However, since the virus is believed to have originated in civet cats and other wildlife sold for human consumption in open markets, the Centers for Disease Control advises that travelers to Asia should avoid visiting live food markets and having direct contact with civets and other wildlife from these markets.

For further information, go to the SARS pages of the World Health Organization, the Centers for Disease Control, and Health Canada. Also see the following:

From the New England Journal of Medicine

Peiris J. S.M., Yuen K. Y., Osterhaus A. D.M.E., Stöhr K. Current Concepts: The Severe Acute Respiratory Syndrome. N Engl J Med 2003; 349:2431-2441, Dec 18, 2003. Review Article.

Olsen S. J., Chang H.-L., Cheung T. Y.-Y., Tang A. F.-Y., Fisk T. L., Ooi S. P.-L., Kuo H.-W., Jiang D. D.-S., Chen K.-T., Lando J., Hsu K.-H., Chen T.-J., Dowell S. F. Transmission of the Severe Acute Respiratory Syndrome on Aircraft. N Engl J Med 2003; 349:2416-2422, Dec 18, 2003.

From Emerging Infectious Diseases

2004 SARS Edition