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A spokesman for the Centre for Health Protection (CHP) of the Department of Health announced the latest laboratory results of water samples taken after thorough cleansing and disinfection of office buildings in connection with a confirmed Legionnaires' Disease case involving a 67-year-old male patient available today (January 20). So far, 293 water samples had final results available and none exceeded the action level of 1 colony-forming unit per millilitre (cfu/ml).
These 293 samples included 120 samples processed by the Public Health Laboratory of CHP and the Chinese University of Hong Kong and 173 from an accredited private laboratory. These 293 samples included 108 taken from the Central Government Offices, 159 from the Legislative Council Complex, 17 from the Chief Executive's Office, and nine from Tamar Park.
Legionella bacteria was below the detection limit of 0.1 cfu/ml in 284 of the water samples. Nine water samples showed low levels ranging from 0.1 to 0.5 cfu/ml, which are below the action level of 1 cfu/ml.
Furthermore, with regard to all 19 locations where pre-disinfection water samples were deemed positive earlier, all the post-disinfection samples now have a legionella count below the action level of 1 cfu/ml. They included 23 samples tested by CHP and three samples tested by the accredited private laboratory.
Following the disinfection exercise, the CHP together with the Architectural Services Department and the Water Supplies Department conducted systematic post-disinfection sampling of water samples at the Chief Executive's Office, the Legislative Council Complex, the Central Government Offices and Tamar Park for further tests to ensure that the Legionella bacterial count has returned to normal levels.
A total of 451 post-disinfection water samples were collected from the whole Tamar site for further testing of Legionella pneumophila. Testing of 293 samples has been completed and the results were available today. Testing of the remaining 158 samples processed by the private laboratory is expected to be completed after the Chinese New Year.
As it takes time for the Legionella bacteria to grow in culture, it is possible that a certain number of remaining samples at their final stage of testing may yield positive results eventually, but their levels are expected to be lower than the samples taken before disinfection, the spokesman added.
Ends/Friday, January 20, 2012
Issued at HKT 19:44
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