Laboratory Diagnosis of SARS

摘要

The virologic test results of 415 patients with severeacute respiratory syndrome (SARS) were examined. Thepeak detection rate for SARS-associated coronavirusoccurred at week 2 after illness onset for respiratory speci-mens, at weeks 2 to 3 for stool or rectal swab specimens,and at week 4 for urine specimens. The latest stool samplethat was positive by reverse transcription–polymerase chainreaction (RT-PCR) was collected on day 75 while the patientwas receiving intensive care. Tracheal aspirate and stoolsamples had a higher diagnostic yield (RT-PCR averagepositive rate for first 2 weeks: 66.7% and 56.5%, respective-ly). Pooled throat and nasal swabs, rectal swab, nasal swab,throat swab, and nasopharyngeal aspirate specimens pro-vided a moderate yield (29.7%–40.0%), whereas throatwashing and urine specimens showed a lower yield (17.3%and 4.5%). The collection procedures for stool and poolednasal and throat swab specimens were the least likely totransmit infection, and the combination gave the highestyield for coronavirus detection by RT-PCR. Positive virolog-ic test results in patient groups were associated withmechanical ventilation or death (p < 0.001), suggesting acorrelation between viral load and disease severity