Introduction

Severe acute respiratory syndrome (SARS) is a newly emerged disease caused by a previously unknown coronavirus. It joins a long list of emerging infections. However, unlike other contenders such as avian influenza, Nipah virus, Hendra virus or hantaviruses it has established the capacity for efficient human-to-human transmission and thus poses a major threat to international public health. For this reason, the World Health Organisation (WHO) has described SARS as the first serious and readily transmissible disease to emerge in the 21st century.

The first known cases of SARS occurred in Guangdong Province in southern China in late November 2002. The first official report of an outbreak of atypical pneumonia in the province on 11 February 2003 indicated that the disease had affected 305 persons and caused five deaths, and that around 30% of cases had occurred in health care workers. On 21 February 2003, a medical doctor infected with SARS travelled from Guangzhou, the provincial capital, and stayed one night at a hotel in Hong Kong. He infected at least 16 other guests and visitors in the hotel. Within days, the disease began spreading around the world along international air travel routes as hotel contacts seeded hospital outbreaks in Hong Kong, Vietnam, Singapore and Canada (Figure 1.1).