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Volume 10, Number 2—February 2004
THEME ISSUE
2004 SARS Edition

SARS Epidemiology

SARS Surveillance during Emergency Public Health Response, United States, March–July 2003

Stephanie J. Schrag*Comments to Author , John T. Brooks*, Chris Van Beneden*, Umesh D. Parashar*, Patricia M. Griffin*, Larry J. Anderson*, William J. Bellini*, Robert F. Benson*, Dean D. Erdman*, Alexander Klimov*, Thomas G. Ksiazek*, Teresa C.T. Peret*, Deborah F. Talkington*, W. Lanier Thacker*, Maria L. Tondella*, Jacquelyn S. Sampson*, Allen W. Hightower*, Dale F. Nordenberg*, Brian D. Plikaytis*, Ali S. Khan*, Nancy E. Rosenstein*, Tracee A. Treadwell*, Cynthia G. Whitney*, Anthony E. Fiore*, Tonji M. Durant*, Joseph F. Perz*, Annemarie Wasley*, Daniel Feikin*, Joy L. Herndon*, William A. Bower*, Barbara W. Kilbourn*, Deborah A. Levy*, Victor G. Coronado*, Joanna Buffington*, Clare A. Dykewicz*, Rima F. Khabbaz*, and Mary E. Chamberland*
Author affiliations: *Centers for Disease Control and Prevention, Atlanta, Georgia, USA

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Table 2

CDC SARS case definition, United States, as of July 31, 2003a

Case classificationb
Probable case: meets the clinical criteria for severe respiratory illness of unknown etiology and epidemiologic criteria; laboratory criteria confirmed or undetermined
Suspect case: meets the clinical criteria for moderate respiratory illness of unknown etiology and epidemiologic criteria; laboratory criteria confirmed or undetermined
Clinical criteria
Asymptomatic or mild respiratory illness
Moderate respiratory illness: temperature >38°Cc and one or more clinical findings of respiratory illness (e.g., cough, shortness of breath, difficulty breathing, hypoxia)
Severe respiratory illness: criteria for moderate respiratory illness with radiographic evidence of pneumonia, respiratory distress syndrome, or autopsy findings consistent with pneumonia or respiratory distress syndrome without an identifiable cause
Epidemiologic link criteria
Travel (including airport transit ) within 10 days of onset of symptoms to area with current or recently documented or suspected community transmission of SARS (Table 3) or close contactd within 10 days of symptom onset with person known or suspected to have SARS
Laboratory criteriae
Confirmed: detection of antibody to SARS-CoV in a serum sample; detection of SARS-CoV RNA by RT-PCR confirmed by a second PCR assay by using a second aliquot of the specimen and a different set of PCR primers; or isolation of SARS-CoV
Negative: absence of antibody to SARS-CoV in convalescent serum obtained >28 days after symptom onsetf
Undetermined: laboratory testing not performed or incomplete
Exclusion criteria
Illness fully explained by alternative diagnosisg
Convalescent-phase serum sample (obtained >28 days after symptom onset) negative for antibody to SARS-CoV.
Case reported on basis of contact with index case subsequently excluded as SARS, provided other epidemiologic exposure criteria are not present

aCDC, Centers for Disease Control and Prevention; SARS, severe acute respiratory syndrome; CoV, coronavirus; RT-PCR, reverse transcriptase–polymerase chain reaction.

bAsymptomatic SARS-CoV infection or clinical manifestations other than respiratory illness might be identified as more is learned about SARS-CoV infection.

cMeasured documented temperature of >38°C is preferred; however, clinical judgment should be used when evaluating patients for whom temperature of >38°C has not been documented. Factors that might be considered include patient self-report of fever, use of antipyretics, presence of immunocompromising conditions or therapies, lack of access to health care, or inability to obtain a measured temperature. Reporting authorities should consider these factors when classifying patients who do not strictly meet the clinical criteria for this case definition.

dClose contact is defined as having cared for or lived with a person known to have SARS or having a high likelihood of direct contact with respiratory secretions or body fluids of a patient with SARS. Examples of close contact include kissing or embracing, sharing eating or drinking utensils, close conversation (<3 feet), physical examination, and any other direct physical contact. Close contact does not include activities such as walking near a person or sitting across a waiting room or office for a brief period.

eAssays to diagnose SARS-CoV infection include enzyme-linked immunosorbent assay, indirect fluorescent-antibody assay, and RT-PCR assays of appropriately collected clinical specimens. Absence of SARS-CoV antibody from serum obtained <28 days after illness onset,f a negative PCR test, or a negative viral culture does not exclude SARS-CoV infection and is not considered a definitive laboratory result. In these instances, a convalescent-phase serum sample obtained >28 days after illness is needed to determine infection with SARS-CoV.g All SARS diagnostic assays are under evaluation.

fDoes not apply to serum samples collected before July 11, 2003. Testing results from serum samples collected before July 11, 2003 and between 22 and 28 days after symptom onset are acceptable and will not require collection of additional sample >28 days after symptom onset.

gFactors that may be considered in assigning alternate diagnoses include strength of epidemiologic exposure criteria for SARS, specificity of diagnostic test, and compatibility of clinical presentation and course of illness for alternative diagnosis.

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