Update: Severe Acute Respiratory Syndrome --- United States, 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). During November 1, 2002--April 30, 2003, a total of 5,663 SARS cases were reported to WHO from 26 countries, including the United States; 372 deaths (case-fatality proportion: 6.6%) have been reported (1). This report updates information on reported SARS cases among U.S. residents and provides an overview regarding CDC's issuance of travel alerts and advisories.
As of April 30, a total of 289 SARS cases were reported to CDC from 38 states, of which 233 (81%) were classified as suspect SARS, and 56 (19%) were classified as probable SARS (more severe illnesses characterized by the presence of pneumonia or acute respiratory distress syndrome) (Figure 1, Table) (2). Laboratory testing to evaluate infection with the SARS-associated coronavirus (SARS-CoV) has been completed for 60 cases. Laboratory-confirmed infection, based on detection of antibody to SARS-CoV in serum or evidence of virus in clinical specimens by reverse transcriptase polymerase chain reaction analysis, has been identified in six patients; all were probable cases, as described previously (3,4). Negative findings (i.e., the absence of antibody to SARS-CoV in convalescent serum obtained >21 days after symptom onset) have been documented for 54 cases (41 suspect and 13 probable).
Of the 56 probable SARS patients, 37 (66%) were hospitalized, and two (4%) required mechanical ventilation. One patient (2%) was a health-care worker who provided care to a SARS patient, and one (2%) was a household contact of a SARS patient. The remaining 54 (96%) probable SARS patients (including the six patients with positive SARS-CoV laboratory results) had traveled to mainland China; Hong Kong Special Administrative Region, China; Singapore; Hanoi, Vietnam; or Toronto, Canada.
As of April 30, the SARS outbreak control strategy for the United States has included issuance of travel alerts and advisories and distribution of health alert notices to travelers arriving from areas with SARS to facilitate early identification of imported cases. Current travel alerts (Hanoi and Toronto) and advisories (Hong Kong, Taiwan, mainland China, and Singapore) can be found at http://www.cdc.gov/ncidod/sars/travel.htm.
Health alert notices, which have been translated into seven languages (Chinese [Simplified and Traditional], French, Japanese, Korean, Spanish, and Vietnamese), inform the returning traveler of potential exposure to cases of SARS. They alert travelers to the symptoms of SARS and to promptly seek medical attention if symptoms develop. Travelers should call their health-care provider in advance to report recent travel to areas with SARS. The notices also provide information and additional instructions for physicians.
During March 16--April 29, CDC distributed 735,370 health alert notices to travelers arriving from the areas with SARS in Southeast Asia at 22 airports at points of entry into the United States. As of April 26, health alert notices have been distributed at the Lester B. Pearson International Airport in Toronto to embarking U.S. passengers destined for 58 airports in the United States (Figure 2) and overland crossings of the U.S.-Canadian border (Figure 3). In addition, copies of health alert notices have been provided to cargo and cruise ship lines for distribution to crew and passengers.
As of April 30, 96% of probable U.S. SARS cases have occurred among international travelers, with only two instances of secondary transmission associated with these cases (5). Since the previous SARS update (4), no additional laboratory-confirmed cases have been identified. The collection and testing of convalescent serum is critical for laboratory confirmation of cases that have undetermined laboratory status.
CDC issues travel alerts and advisories based on evidence of transmission in areas with SARS, translocation of the disease, and the effectiveness of local prevention efforts. The quality of local disease surveillance and the accessibility of medical care in areas with SARS are additional considerations. The definitions of travel alerts and advisories are available at http://www.cdc.gov/ncidod/sars/travel_alertadvisory.htm.
Travel alerts and advisories are notifications that an outbreak of a disease is occurring in a geographic area outside of the United States. A travel alert, the lower-level notice, provides information about the disease outbreak and informs travelers and resident expatriates of ways to reduce their risk for infection. An alert does not include a recommendation against nonessential travel to the area. When the health risk for travelers is thought to be high, a travel advisory is issued that recommends against nonessential travel to the area. Travel advisories are intended to reduce the number of travelers to areas with SARS and the risk for translocating disease to other areas.
In response to the SARS outbreak, CDC provided health alert notices to travelers returning from areas with SARS to promptly detect potential cases of SARS. These health alert notices also helped raise awareness of SARS among health-care providers and the general public.
Travel alerts and advisories are disseminated through media advisories, press briefings, e-mail notifications, and State Department advisories. They are posted routinely on the CDC Travelers' Health website at http://www.cdc.gov/travel. Health alert notices can be found at http://www.cdc.gov/ncidod/sars/travel_alert.htm.
- World Health Organization. Cumulative number of reported cases of severe acute respiratory syndrome (SARS). Available at http://www.who.int/csr/sarscountry/2003_04_30/en.
- CDC. Updated interim U.S. case definition of severe acute respiratory syndrome (SARS). Available at http://www.cdc.gov/ncidod/sars/casedefinition.htm.
- CDC. Severe acute respiratory syndrome (SARS) and coronavirus testing---United States, 2003. MMWR 2003;52:297--302.
- CDC. Update: severe acute respiratory syndrome---United States, 2003. MMWR 2003;52:357--60.
- CDC. Update: severe acute respiratory syndrome---United States, 2003. MMWR 2003;52:332--6.
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