The following is issued on behalf of the World Health Organisation:
It is highly likely that an unlucky set of environmental and health events happening simultaneously contributed to the spread of SARS in the Hong Kong residential estate of Amoy Gardens in March 2003, a World Health Organisation (WHO) environmental health team has found.
Presenting its initial finding to the Hong Kong Department of Health, the WHO environmental health team leader, Dr Heinz Feldmann, said around March 21, 2003 an unusual cluster of SARS cases occurred in Block E of the Amoy Gardens Estate with apartment units 7 and 8 most affected.
"At the invitation of the Hong Kong health authorities my team has explored the risk factors involved in the possible environmental transmission of SARS in this housing estate and has concluded that a number of factors are probably responsible for the unusual spread of the virus," Dr Feldmann said.
These events include:
*At the time of the outbreak, the floor drain traps (which when filled up with water are designed to prevent a reflux and act as a barrier between the floor drain and the soil stack) in many apartments seemed to have dried out and did not contain water for long periods.
*Exhaust fans that have been installed in bathrooms were running with the door closed and contaminated droplets could have been drawn from the soil stack into the bathroom through the dried out floor drains.
*The running exhaust fans could have also transported contaminated droplets present or generated in the bathroom into the light well, and then the contaminated droplets could have entered into other apartments with an open window even several floors away from the source.
*Flush water was shut down for 16 hours starting on the evening of March 21, 2003, to fix a break of a flush water pipe serving unit 8.
"The physical condition of the Amoy Gardens structure is generally good and meets international standards," Dr Feldmann said.
"The management of the building is delivered professionally and existing plumbing systems meet the needs to contain waste within piping, provided it is operated by the multitude of users as per original design intent.
"Our exhaustive testing of Amoy Gardens found no genetic material or footprint of the SARS related coronavirus in swabs taken from the affected apartments, the entrance between the units, the corridors, the roof, the ground floor and the sewer manholes.
"There was no evidence of live virus from the collected swabs," he said.
The WHO environmental team, all from Health Canada, comprises:
*Dr Heinz Feldmann (team leader) - infectious diseases specialist/virologist, specialising in sampling, interpretation of data and epidemiology of communicable diseases.
*Mr Immo Tilgner - has extensive expertise in mechanical building systems, including evaluation of ventilation and plumbing systems.
*Mr Allen Grolla - specialising in technical sampling and analysis and molecular detection of viruses.
*Dr Ramon Flick - virologist with expertise in mechanical virology sampling and analysis and virus isolation from different samples.
A full and final report on the WHO investigations will be produced in due course.
Media contact: Kay McNiece, WHO Information Officer, Hong Kong SAR
2961 8981 (Hong Kong) 001 61 412 132 585 (mobile)
End/Friday, May 16, 2003