1 figure, 1 table omitted
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 highlights recent modifications to
the U.S. SARS case definition that define criteria for exclusion of previously
reported SARS cases and for reporting travel-associated cases of SARS.
During November 1, 2002–May 21, 2003, a total of 7,956 SARS cases
were reported to WHO from 28 countries, including the United States; 666 deaths
(case-fatality proportion: 8.4%) have been reported.1 A total of
355 SARS cases identified in the United States have been reported from 40
states with 290 (82%) cases classified as suspect SARS and 65 (18%) classified
as probable SARS (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 last update.3
Of the 65 probable SARS patients, 41 (63%) were hospitalized, and two
(3%) required mechanical ventilation. No SARS-related deaths have been reported
in the United States. Of 65 probable cases, 63 (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. Among the 63 probable SARS cases attributed
to travel, 33 (52%) patients reported travel to mainland China; 19 (30%) to
Hong Kong Special Administrative Region, China; six (10%) to Singapore; two
(3%) to Hanoi, Vietnam; nine (14%) to Toronto, Canada; and one (2%) to Taiwan.
Of the probable SARS patients, five (8%) had visited more than one area with
SARS during the 10 days before illness onset.
Laboratory testing to evaluate infection with the SARS-associated coronavirus
(SARS-CoV) has been completed for 122 cases (26 probable and 96 suspect).
Since the last update,3 the number of cases with laboratory-confirmed
infection with SARS-CoV remains at six; all are probable SARS cases with no
suspect SARS cases having laboratory evidence of infection with SARS-CoV.
Negative findings (i.e., the absence of antibody to SARS-CoV in convalescent
serum obtained >21 days after symptom onset) have been documented for 116
cases (96 suspect and 20 probable).
The number of new cases reported in the United States has been decreasing
in recent weeks. The epidemiologic profile of reported cases remains unchanged
with most cases associated with international travel and few instances of
secondary spread to family members or other contacts. However, vigilance is
critical to ensure rapid recognition and appropriate management of persons
The low specificity of the surveillance case definition captures many
persons unlikely to have SARS. The CDC surveillance case definition has been
revised to include interim criteria for excluding new or previously reported
suspect or probable cases of SARS for whom an alternative diagnosis can fully
explain the patient's illness.2 Factors that might be considered
in assigning alternative diagnoses include the strength of the epidemiologic
exposure criteria for SARS, the specificity of the diagnostic tests, and the
compatibility of the clinical presentation and course of illness for the alternative
diagnosis. The epidemiologic criteria for travel exposure also have been revised
and now reflect updated information about the occurrence of community transmission
in areas with SARS. Hanoi, Vietnam and Toronto, Canada are now considered
areas with previous community transmission of SARS because >30 days have elapsed
since the onset of symptoms for the last reported case.4 As a result,
travel alerts for these cities were removed on May 15 and May 20, respectively.
Persons reporting travel to these areas will meet the surveillance case definition
if illness onset occurred within 10 days (i.e., one incubation period) after
removal of the travel alert.
These revisions to the case definition are 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.
As state and local health departments review and reclassify cases using
these new criteria, case counts might change but the result will more accurately
reflect the occurrence of SARS in the United States.
State and local health departments. SARS Investigative Team, CDC.
References: 4 available
Update: Severe Acute Respiratory Syndrome—United States, May 21, 2003. JAMA. 2003;289(22):2932. doi:10.1001/jama.289.22.2932-a