Health Information
LABORATORY TESTING FOR SARS

The Delaware Division of Public Health (DPH) has investigated several reports of SARS in Delaware, but none have met the clinical and epidemiologic case definition. This update provides information about the availability of laboratory testing for SARS.

LABORATORY TESTS

SARS has been associated etiologically with a novel coronavirus, SARS-CoV. Evidence of SARS-CoV infection has been identified in patients with SARS in several countries, including the United States. Several new laboratory tests can be used to detect SARS-CoV. Serologic testing for coronavirus antibody can be performed by using indirect fluorescent antibody or enzyme-linked immunosorbent assays that are specific for antibody produced after infection. Although some patients have detectable coronavirus antibody during the acute phase (i.e., within 14 days of illness onset), definitive interpretation of negative coronavirus antibody tests is possible only for specimens obtained >21 days after onset of symptoms. A reverse transcriptase polymerase chain reaction (RT-PCR) test specific for viral RNA has been positive within the first 10 days after onset of fever in specimens from some SARS patients, but the duration of detectable viremia or viral shedding is unknown. RT-PCR testing can detect SARS-CoV in clinical specimens, including serum, stool, and nasal secretions. Finally, viral culture and isolation have both been used to detect SARS-CoV. Absence of SARS-CoV antibody in serum obtained <21 days after illness onset, a negative PCR test, or a negative viral culture does not exclude coronavirus infection.

Reference: CDC, http://www.cdc.gov/mmwr/preview/mmwrhtml/mm52d429a1.htm, April 29, 2003.

CRITERIA FOR LABORATORY CONFIRMATION

• Detection of antibody to SARS-CoV in specimens obtained during acute illness or >21 days after illness onset, OR
• 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 (Centers for Disease Control and Prevention

Reference: CDC, http://www.cdc.gov/mmwr/preview/mmwrhtml/mm52d429a1.htm, April 29, 2003

HOW TO OBTAIN LABORATORY TESTING

The Delaware Division of Public Health Laboratory (DPHL) anticipates the capacity to conduct PCR SARS testing within the next several weeks. At this time, the availability of an antibody test for state health departments is uncertain. Until DPHL testing is available, DPHL will facilitate SARS testing of Delaware suspect cases by CDC. Specimens for laboratory testing should be submitted to the DPHL only for patients who meet clinical and epidemiologic criteria. These criteria are:

Respiratory illness of unknown etiology with onset since February 1, 2003, and the following criteria:

• Measured temperature greater than 100.4°F (greater than 38°C) AND
• One or more clinical findings of respiratory illness (e.g., cough, shortness of breath, difficulty breathing, or hypoxia) AND
• Travel† within 10 days of onset of symptoms to an area with documented or suspected community transmission of SARS (see list below; excludes areas with secondary cases limited to healthcare workers or direct household contacts) OR
• Close contact* within 10 days of onset of symptoms with a person known to be a suspect SARS case.

†Travel includes transit in an airport in an area with documented or suspected community transmission of SARS.

Areas with documented or suspected community transmission of SARS: People's Republic of China (i.e., mainland China and Hong Kong Special Administrative Region); Hanoi, Vietnam; Singapore; and Toronto, Canada.

*Close contact is defined as having cared for, having lived with, or having direct contact with respiratory secretions and/or body fluids of a patient known to be suspect SARS case.

Call the Division of Public Health Laboratory at (302) 653-2870 for further information about laboratory testing and to coordinate the submission of specimens for analysis.

SPECIMEN COLLECTION

Outpatient

• Upper Respiratory: nasopharyngeal and oralpharyngeal swabs
• Blood: Serum (acute and convalescent), whole blood
• Stool

Inpatient

• Upper Respiratory: nasopharyngeal aspirate, nasopharyngeal and oralpharyngeal swabs
• Lower Respiratory: Broncheoalveolar lavage (BAL), tracheal aspirate or pleural tap
• Blood: Serum (acute and convalescent), whole blood
• Stool

For further details about specimen collection, see:   http://www.cdc.gov/ncidod/sars/specimen_collection_sars2.htm.