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Special Articles: Review of Literature: General Infectious Diseases

Viral Shedding Patterns of Coronavirus in Patients With Probable Severe Acute Respiratory Syndrome

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Infectious Diseases in Clinical Practice: November 2004 - Volume 12 - Issue 6 - p 387
doi: 10.1097/01.idc.0000144912.27311.19
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Viral Shedding Patterns of Coronavirus in Patients With Probable Severe Acute Respiratory Syndrome Cheng PKC et al. Lancet. 2004;363:1699

This is a report from Hong Kong on results of RT-PCR for detection of the SARS coronavirus RNA in 2134 specimens from 1041 patients with documented infection. The most frequently positive specimens were nasopharyngeal aspirates with a yield of 45% and stool with a yield of 28%. The peak time of positive results for nasopharyngeal aspirates was at 6 to 11 days after the onset of illness when 87 (58%) of 149 were positive. For stool, the peak was at 9 to 14 days. The overall results showed that the peak viral load was reached at 12 to 14 days of illness when patients were usually in hospital care making healthcare workers particularly vulnerable; the viral shedding was relatively low in the early stages of disease making diagnostic testing of low yield. The results for all specimens tested are summarized in the following table:

Table
Table:
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The authors conclude that the yield with this test is highly variable depending on the timing of the test and the specimen tested. The highest yield is at least 6 days after the onset of illness so that one of their recommendations is to test 6 days or later if the initial test is negative. High yield in stool presumably accounts for GI shedding as a potentially important role in transmission.

© 2004 Lippincott Williams & Wilkins, Inc.