SARS epidemiology to date
11 April 2003
- SARS is a new disease which has its origins in Guangdong Province, China. The earliest known cases were identified in mid-November 2002. Since then, probable cases of SARS have been reported in 17 countries.
- WHO is constantly investigating and, where appropriate, verifying rumours about SARS coming in from a wide range of sources.
- The current cumulative number of cases of SARS is 2781 cases with 111 deaths, officially notified by ministries of health. The global case-fatality rate for probable SARS is 4%.
- Most SARS cases to date have occurred in young adults. This transmission pattern largely reflects the age of health care workers, their family members and social contacts, and international travellers. On the basis of present data, children appear to be less likely to present with SARS than adults.
- SARS appears to be spread most commonly by close person-to-person contact involving exposure to infectious droplets, and possibly by direct contact with infected body fluids.
- China continues to see new cases of SARS although the numbers are decreasing following a peak in cases in February. To date, 1290 cases and 55 deaths have been reported from mainland China.
- Hong Kong is experiencing the second largest outbreak of SARS with 998 cases and 30 deaths. A significant outbreak at the Amoy Gardens apartment block between 27 March to 1 April resulted in a peak in cases. Stringent public health measures appear to have controlled the Amoy Gardens outbreak. However, cases continue to be reported in health care workers, and Hong Kong health authorities are strengthening their infection control and community-based public health measures accordingly.
- Canada has experienced an outbreak of 97 probable SARS cases and 10 deaths. Up to now, the outbreak has been largely confined to Toronto. All cases have been epidemiologically linked to transmission related to a health care setting and transmission among close contacts of known SARS cases. In the Canadian outbreak, the higher case-fatality ratio appears to be linked to the older age of the patients, who frequently have underlying chronic disease.
- Infection control and other public health measures implemented in Viet Nam have effectively controlled the outbreak in Hanoi. Very low levels of transmission have been reported after 24 March. Since the outbreak began on 26 February, 4 deaths have been reported.
- Although Singapore continues to see new cases, including clusters in hospital staff, inpatients, and visitors at two hospitals, the daily increase in numbers has decreased since a peak in mid-March. As of 10 April, a cumulative total of 126 cases with 9 deaths has been reported. Singapore is currently investigating a new cluster at the Singapore General Hospital affecting 52 persons in Wards 57 and 58, comprising 19 probable and 33 suspect SARS cases. The index case was admitted to this hospital on 24 March for the management of unrelated chronic illness, did not show characteristic SARS symptoms initially, and therefore was not placed in isolation and managed according to the principles of strict infection control.
- Cases continue to increase in the United States with 154 persons under investigation. US figures include probable and suspect cases. The US now reports limited transmission from patients to health care workers. No deaths have so far been reported from the US.
- Areas defined as "affected" are updated each day according to the latest data on cases and evidence of patterns of transmission. Epidemiological data indicate that SARS cases occurring in all other countries became infected while present in one of the affected areas or by direct contact with known cases of SARS.