2 tables omitted
During the 2003 epidemic of severe acute respiratory syndrome (SARS),
CDC and the Council of State and Territorial Epidemiologists (CSTE) developed
surveillance criteria to identify persons with SARS. The surveillance case
definition changed throughout the epidemic as understanding of the clinical,
laboratory, and transmission characteristics of SARS-associated coronavirus
(SARS-CoV) increased.1-5 On June 26, CSTE adopted a position statement
to add SARS-CoV disease to the National Notifiable Disease Surveillance System
(NNDSS). The position statement included criteria for defining a SARS case
for national reporting. On November 3, CSTE issued a new interim position
statement* with a revised SARS case definition. This report summarizes the
new U.S. surveillance case definition for SARS and updates reported cases
of SARS worldwide and in the United States.
The revised SARS case definition [available online at
modifies the clinical, epidemiologic, laboratory, and case-exclusion
criteria in the U.S. surveillance case definition used during the 2003 epidemic.
In the clinical criteria, "early" illness replaces "asymptomatic" or "mild"
illness. The epidemiologic criteria include the following new categories:
(1) possible exposure to SARS-CoV and (2) likely exposure to SARS-CoV. Laboratory
criteria for evidence of SARS-CoV infection reflect advances in testing technology.
The case-exclusion criteria have been changed to allow for exclusion when
a serum sample collected >28 days after onset of symptoms is negative for
antibody to SARS-CoV.
The revised case definition also classifies each SARS case as either
a SARS report under investigation (SARS RUI) or SARS-CoV disease. SARS RUI
is a sensitive, nonspecific case classification based solely on clinical or
epidemiologic criteria and includes cases classified previously as probable
or suspect. SARS-CoV disease is a more specific case classification based
on selected clinical and epidemiologic criteria or laboratory confirmation.
SARS RUIs might subsequently meet the definition for SARS-CoV disease based
on results from laboratory testing.
During November 2002–July 2003, a total of 8,098 probable SARS
cases were reported to the World Health Organization (WHO) from 29 countries,
including 29 cases from the United States; 774 SARS-related deaths (case-fatality
rate: 9.6%) were reported, none of which occurred in the United States.6 Eight U.S. cases had serologic evidence of SARS-CoV infection; these
eight cases have been described previously.7-10 A total of 156
reported U.S. SARS cases from the 2003 epidemic remain under investigation,
with 137 (88%) cases classified according to previous surveillance criteria
as suspect SARS and 19 (12%) classified as probable SARS. Because convalescent
serum specimens have not been obtained from the 19 probable and 137 suspect
cases that remain under investigation, whether these persons had SARS-CoV
disease is unknown.
SARS Team and Executive Committee, Council of State and Territorial
Epidemiologists. SARS Investigative Team, CDC.
The revised surveillance case definition for SARS reflects an improved
understanding of the clinical and laboratory characteristics of SARS-CoV.
The revision differentiates patients with nonspecific clinical illness or
less definitive epidemiologic associations (i.e., SARS RUIs) from those with
laboratory-confirmed SARS-CoV infection or more definitive epidemiologic links
(i.e., cases of SARS-CoV disease). Local and state health departments will
monitor SARS RUIs to ensure implementation of prompt public health measures
for preventing disease transmission if SARS-CoV is confirmed subsequently.
Numerous SARS RUIs probably will be excluded as SARS cases as laboratory results
become available during the course of illness. Surveillance data for cases
meeting the SARS-CoV disease case definition will be reported to NNDSS and
included in the weekly statistical summary of notifiable infectious diseases
in the United States published in MMWR (Table 1.
Summary of provisional cases of selected notifiable diseases, United States).
Reporting of cases meeting previous SARS definitions ended in late July
2003. However, case numbers continue to change as new clinical information
or results of additional laboratory testing on cases reported previously become
available. Updated case counts reflecting these changes are available from
CDC at http://www.cdc.gov/od/oc/media/sars/cases.htm.
Efforts are under way to prepare for a possible reappearance of SARS-CoV.
CDC, in collaboration with other federal partners, state and local health
officials, professional organizations and societies, and representatives of
the health-care industry, has developed a guidance document to help public
health and health-care officials detect the reappearance of SARS-CoV in the
United States quickly and implement a decisive and effective public health
response. The document, "Public Health Guidance for Community-Level Preparedness
and Response to Severe Acute Respiratory Syndrome (SARS)," is available at http://www.cdc.gov/ncidod/sars/sarsprepplan.htm.
References: 10 available
*The interim position statement must be ratified by the entire membership
at the 2004 annual CSTE meeting. The statement is available from CSTE at http://www.cste.org/ps/2003pdfs/2003finalpdf/cstesarscasedefrevision2003-10-30.pdf.
Revised U.S. Surveillance Case Definition for Severe Acute Respiratory Syndrome (SARS) and Update on SARS Cases—United States and Worldwide, December 2003. JAMA. 2004;291(2):173-174. doi:10.1001/jama.291.2.173