Accurate Clinical Prediction of Severe Acute Respiratory Syndrome: Are We There Yet?

The spring 2003 outbreak of severe acute respiratory syndrome (SARS), which resulted in more than 8000 cases and 774 deaths (1), severely challenged public health and health care systems globally. It is not possible to predict whether a large SARS outbreak will recur, but several potential sources of a resurgence exist.

The SARS-associated coronavirus is believed to be of zoonotic origin (2), and while its natural reservoir or reservoirs are unknown, several exotic species (for example, civet cats and raccoon dogs) sold for consumption in southern China have shown evidence of infection (3). Thus, these reservoirs could serve as sources for human exposure to the virus. In December 2003 and January 2004, almost 6 months after the end of the global SARS outbreak, 4 unlinked cases of SARS were reported in Guangdong, the province in China where SARS first emerged (4). The source of infection for these cases was not conclusively determined, but 1 patient worked in a restaurant that served civets, and environmental samples from cages that housed these animals yielded evidence of SARS coronavirus (5). In addition, the genomic sequence of virus detected from a second patient differed from that of virus isolated from humans during the spring 2003 outbreak; however, the sequence closely resembled that of SARS coronavirus isolated from civets in late 2003 (3). Collectively, these findings suggest that reintroduction of SARS coronavirus from infected animals remains a distinct possibility.

Another potential source of SARS coronavirus exposure is laboratories that store specimens containing the virus or that use live virus for diagnostic or research purposes. Since fall 2003, 6 persons have become infected with SARS coronavirus in 3 laboratories in Singapore, Taiwan, and China (6-8), and 1 of these patients infected 7 additional persons through 2 chains of transmission, …