With the outbreak of severe acute respiratory syndrome (SARS) entering its third week, by March 24 the patient toll in Hong Kong reached 260 confirmed cases and five cases yet to be confirmed.One of those with suspected illness is William Ho, chief executive of the Hong Kong Hospital Authority, which runs all 44 public hospitals and clinics. Ho was admitted to hospital on March 23 with suspected pneumonia and other symptoms consistent with the disease, although his exact illness has not been diagnosed.So far, ten people have died in the outbreak, which was recognised on March 8 when three hospital staff of the Prince of Wales Hospital developed atypical pneumonia.Four Hong Kong schools where six pupils have been confirmed with the disease were also shut for 1 week as the government struggled to curb the spread of the virus. And more than 180 students whose family members were infected hospital workers have been suspended from attending classes.The virus is believed to be spread by droplets from an infected person's coughs or sneezes, and its incubation period is 2–7 days.Epidemiological studies by the Department of Health found that the global outbreak was connected to a mainland doctor, who had been sick in his native Guangzhou City before arriving in Hong Kong on Feb 21.The 64-year-old doctor infected guests and visitors at his hotel, and by Feb 22, he was admitted to a hospital where he died on March 4. An American-Chinese businessman who flew on to Hanoi, three Singaporeans, two Canadians, and a Hong Kong airport worker who visited the hotel were also infected. The guests in turn sparked outbreaks of SARS in their respective countries.The airport worker triggered the Hong Kong outbreak when he was admitted to Prince of Wales Hospital on March 5.The isolation of the virus by the Hong Kong laboratory is a major step towards development of a diagnostic test, said Shigeru Omi, WHO's regional director for the Western Pacific.“However, we should not get carried away”, he said. “These are preliminary results only. Further studies are needed before it can be concluded, with confidence, that the causative agent of SARS has been identified.”“The SARS virus travels at the speed of a jumbo jet. Its potential to spread and cause harm is obvious”, he said.