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Mary Ann Benitez

Virus was introduced to the estate by infected kidney patient

Sewage system behind Amoy Gardens outbreak

A faulty sewage system and not airborne or waterborne transmission of the Sars virus led to the outbreak which infected hundreds of residents in Hong Kong's Amoy Gardens, a government report said yesterday.

The report was issued on a day which saw the second consecutive daily fall in the number of new infections and deaths from Sars in Hong Kong. Twenty-nine people were reported to be infected and four more people died.

The report on Amoy Gardens concluded the virus was introduced to the Kowloon Bay estate by an infected kidney patient from Shenzhen who visited the area.

The Amoy Gardens outbreak, which was announced on March 26, prompted the World Health Organisation to issue a travel advisory on April 2 for people to avoid Hong Kong as well as Guangdong.

Up to Tuesday, 321 Amoy Gardens residents were infected in the outbreak, two-thirds of whom had diarrhoea. Eight of the residents have died, including a pregnant woman. The report said that once the virus got into the waste pipe, droplets that carried it apparently moved up through people's bathroom drains when U-shaped water seals failed and the pipe dried out when ventilation fans were switched on.

Water vapour generated during a shower led to the formation of water droplets, which settled on towels and toiletries, the report said.

The faulty drainage system also could have been compounded by the design of the building's lightwell, which provided a 'chimney effect' that allowed droplets to travel up the building through a crack in an air vent.

The 33-year-old kidney patient already had symptoms of Sars when he visited his brother in Unit 7 on the 12th Floor of Block E on March 14 and March 19. He was admitted for suspected atypical pneumonia at Prince of Wales Hospital on March 15 but was treated for flu and discharged four days later. Sars was diagnosed only on a follow-up check on March 22.

About 10 people were infected initially. They then had diarrhoea, depositing a buildup of the virus in the pipes. Person-to-person contact further spread the virus through the use of shared communal facilities such as lifts and staircases in Block E, and residents in other blocks also caught the bug.

Secretary for Health, Welfare and Food Yeoh Eng-kiong said the housing estate's Sars outbreak was 'unique' because of a combination of factors that could not recur.

He hoped this would help the World Health Organisation reconsider its travel advisory on Hong Kong.

The report said cockroaches and rodents were 'passive mechanical carriers''. It said: 'Transmission of the disease by [the] airborne, waterborne route and infected dust aerosols have been examined but these were not supported by the epidemiological picture and laboratory results.'

Secretary for the Environment, Transport and Works Sarah Liao Sau-tong said a study by the University of Hong Kong was looking into how the design of the lightwell could be improved. The lightwell design in Block E means flats stand just 1.5 metres away from each other.

'You could imagine that when there is leakage at any point of the pipe, the droplets could have entered the flats through open windows,'' she said.

University of Hong Kong engineers said yesterday that windows facing the lightwell should be closed at all times to prevent germs from entering households.

An additional 29 patients were confirmed with Sars yesterday, taking the total of 1,297. Four patients died, bringing to the death toll in Hong Kong to 65 so far.

Two were both aged 69 and chronically ill, while a 39-year-old woman had been previously healthy. A total of 272 patients have been discharged.



Sewage system to blame in Amoy Gardens