The virologic test results of 415 patients with severe acute respiratory syndrome (SARS) were examined. The peak detection rate for SARS-associated coronavirus occurred at week 2 after illness onset for respiratory specimens, at weeks 2 to 3 for stool or rectal swab specimens, and at week 4 for urine specimens. The latest stool sample that was positive by reverse transcription–polymerase chain reaction (RT-PCR) was collected on day 75 while the patient was receiving intensive care. Tracheal aspirate and stool samples had a higher diagnostic yield (RT-PCR average positive rate for first 2 weeks: 66.7% and 56.5%, respectively). Pooled throat and nasal swabs, rectal swab, nasal swab, throat swab, and nasopharyngeal aspirate specimens provided a moderate yield (29.7%–40.0%), whereas throat washing and urine specimens showed a lower yield (17.3% and 4.5%). The collection procedures for stool and pooled nasal and throat swab specimens were the least likely to transmit infection, and the combination gave the highest yield for coronavirus detection by RT-PCR. Positive virologic test results in patient groups were associated with mechanical ventilation or death (p < 0.001), suggesting a correlation between viral load and disease severity.

Although it has been recognised that human herpesvirus 7 (HHV-7) establishes latent infection in CD4+ T lymphocytes and productive infection in salivary glands, recent data suggest that its in vivo tropism may be more widespread. In this study, the prevalence and distribution of HHV-7 in brain tissues of 30 consecutive post-mortems were examined by nested polymerase chain reaction. For each post-mortem, 10 fresh autopsy tissue samples were collected respectively from the cerebellum, frontal, temporal, parietal, and occipital lobes of both cerebral hemispheres. These patients were aged from 20-95 years (mean = 61.4, SD = 20.2) with a male:female ratio of 2:1. Three patients died of intracranial haemorrhage, the others died of causes unrelated to the central nervous system. Overall, 5% (15/300) of the brain tissue samples were positive for HHV-7 DNA. The positive rates with respect to anatomical positions were similar (0-3/30). When analysed by patient, 36.7% (11/30) were HHV-7 DNA positive. The viral DNA-positive and -negative groups did not show a significant difference in gender or age distribution. The majority (81.8%) of viral DNA-positive patients had HHV-7 DNA detected at only one anatomical position; only two patients had viral DNA detected simultaneously at three anatomical sites. These results suggest that HHV-7 persists in brain tissues of a substantial proportion of the adult population, and in most individuals, its distribution is probably confined to one site rather than pervasive. Further studies to elucidate the role of this ubiquitous virus in neuropathology are warranted.

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