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Update: Severe Acute Respiratory Syndrome --- United States, June 4, 2003

CDC continues to work with state and local health departments, the World Health Organization (WHO), and other partners to investigate cases of severe acute respiratory syndrome (SARS). This report updates SARS cases reported worldwide and in the United States and summarizes changes in CDC's recommendations for travel to Singapore and Hong Kong and the resulting modification to the interim U.S. case definition for SARS.

During November 1, 2002--June 4, 2003, a total of 8,402 SARS cases were reported to WHO from 29 countries, including the United States; 772 deaths (case-fatality proportion: 9.2%) have been reported (1). A total of 373 SARS cases identified in the United States have been reported from 41 states and Puerto Rico, with 306 (82%) cases classified as suspect SARS and 67 (18%) classified as probable SARS (i.e., more severe illnesses characterized by the presence of pneumonia or acute respiratory distress syndrome) (2). One probable and nine suspect cases have been identified since the previous update (3). No SARS-related deaths have been reported in the United States. Of the 67 probable cases, 65 (97%) were attributed to international travel to areas with documented or suspected community transmission of SARS within the 10 days before illness onset; the remaining two (3%) probable cases occurred in a health-care worker who provided care to a SARS patient and a household contact of a SARS patient. Since the previous update (3), the number of cases with laboratory-confirmed infection with SARS-associated coronavirus (SARS-CoV) remains at seven; all are probable SARS cases, with no suspect SARS cases having laboratory evidence of infection with SARS-CoV.

CDC has downgraded the traveler notification for Hong Kong from a travel advisory to a travel alert (4,5). This change is based on surveillance data from Hong Kong indicating that the symptoms onset date of the last reported patient without a known source of exposure occurred on April 30, 2003, and that more than 20 days, or two SARS incubation periods, have elapsed since that date. Persons who report travel to Hong Kong will continue to meet the surveillance case definition if illness onset occurs within 10 days of travel.

The travel alert for Singapore was removed on June 4 because 30 days (three maximum incubation periods) had elapsed after the date of onset of symptoms for the last case (6). As a result, the epidemiologic criteria for travel exposure in the interim U.S. case definition have been revised. Illness in persons reporting travel to Singapore will be consistent with the surveillance case definition if onset occurred within 10 days (one maximum incubation period) after removal of the travel alert. This revision to the case definition is for surveillance purposes only. Clinical judgment, rather than surveillance criteria, should continue to guide the management of patients and implementation of public health response measures when persons with an unknown respiratory illness are identified.

Reported by: State and local health departments. SARS Investigative Team, CDC.


  1. World Health Organization. Cumulative number of reported cases of severe acute respiratory syndrome (SARS). Available at
  2. CDC. Updated interim U.S. case definition of severe acute respiratory syndrome (SARS). Available at
  3. CDC. Update: severe acute respiratory syndrome---United States, 2003. MMWR 2003;52:500--1.
  4. CDC. Interim definitions and criteria: travel alerts vs. travel advisories. Available at
  5. CDC. Interim travel alert: Hong Kong. Available at
  6. CDC. Travel alert removal: Singapore. Available at

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