A novel coronavirus has been identified as the cause of the 2003 global outbreak of severe acute respiratory syndrome (SARS) (1-5). Genetic analysis and epidemiologic studies suggest that SARS coronavirus (CoV) was introduced into humans not long ago. Recently, SARSCoV -like viruses were isolated in Himalayan palm civets and raccoon dogs in a retail live animal market in Guangdong Province, southern China (6), and some of the animals tested had antibodies to SARS-CoV-like virus. Phylogenetic analysis showed that the SARS-CoV-like animal viruses were closely related to the viruses found in humans. Serologic surveillance demonstrated that, in the same market, approximately 40% of wild animal traders and 20% of animal slaughterers had antibodies to SARSCoV or SARS-CoV-like animal virus, but none of them had had SARS-like symptoms in the past 6 months. These investigations raised questions about whether the presence of the animal SARS-CoV-like virus in the market was an isolated event or if this virus had been prevalent in the human population in southern China before the SARS outbreak. This document includes the results of a retrospective serologic study that was conducted to address these questions. The findings suggest that a small portion of healthy persons in Hong Kong had been exposed to SARS-related viruses at least 2 years before the recent SARS outbreak.
Emerging Infectious Diseases (February 2004), v.10, no.2, p. 176-178