Changing virulence of the SARS virus: the epidemiological evidence.

SARS disease; Coronavirus diseases; Respiratory infections; Microbial virulence; Epidemiology

Severe acute respiratory syndrome (SARS) is a newly described, deadly, communicable disease, first manifested in an epidemic that started in November 2002 in Guangdong Province, China (1). A medical professional who had worked with SARS patients in Guangdong visited Hong Kong on 21 February 2003. The disease quickly spread to 26 countries with local transmission in Singapore, Hanoi,Hong Kong and Toronto. The agent of SARS is an RNA coronavirus, not seen before in humans, known as SARS-CoV (1). The virus has been isolated from specimens (2); the genome has been sequence (3); and infectivity in monkeys has been demonstrated. At the end of the 2003 epidemic, 8098 possible cases and 744 deaths were reported to WHO (4). Although SARS has been controlled, the potential evolution of this virus is not well understood. This paper reviews the epidemiological characteristics of the epidemic; inconsistencies in transmissibility and mortality, the molecular epidemiology of SARS-CoV (4), the results of mathematical modelling, and evidence of evolution towards virulence in pathogens in similar settings. [ABSTRACT FROM AUTHOR]

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