Press Release

Update on epidemiological investigation into case of Legionnaires' disease

20 August 2015

The Centre for Health Protection (CHP) of the Department of Health today (August 20) reported the latest epidemiological investigation into a case of Legionnaires' disease (LD) affecting a man aged 65 who lives in Wing Cheong Estate, Sham Shui Po, Kowloon, released on This link will open in a new windowAugust 4

The patient is now hospitalised in the Intensive Care Unit of Caritas Medical Centre in a serious condition. His tracheal aspirate grew Legionella pneumophila serogroup 1 (Lp1) upon laboratory testing by Princess Margaret Hospital.

Regarding the possible source of infection, water samples and environmental swabs were collected from the patient's residence and from water tanks at the rooftop of Wing Chun House, Wing Cheong Estate, for testing of Legionella during a joint investigation by the CHP and the Housing Department (HD). Upon testing by the CHP's Public Health Laboratory Services Branch, the results are as follows:

• Six out of seven pairs of water samples from water outlets of his residence tested positive for Lp1 at levels from 2.8 to 81 colony-forming units per millilitre (cfu/ml);
• Two pairs of water samples from the water tanks tested positive for Lp1 at levels of 0.1 and 0.4 cfu/ml; and
• Two out of four environmental swabs from his residence tested positive for Lp1.

"As Legionella are found in various environmental settings and aqueous environments, the source is hence yet to be ascertained at this juncture," a spokesman for the CHP said.

"No additional cases have been identified in Wing Cheong Estate thus far. We will maintain close liaison with the HD to monitor the latest developments," the spokesman added.

As a precautionary measure for infection control, the CHP has advised the HD to conduct disinfection of the patient's residence as well as water tanks at the rooftop of Wing Chun House. The HD will also replace the water taps and shower heads at the patient's residence.

"We will provide health advice against LD to relevant residents. Those with weakened immunity should use boiled water for drinking, tooth-brushing and mouth-rinsing, and should avoid using humidifiers or other aerosol-generating devices," the spokesman advised.

Legionella are found in various environmental settings and grow well in warm water (20 to 45 degrees Celsius). They can be found in aqueous environments such as water tanks, hot and cold water systems, cooling towers, whirlpools and spas, water fountains and home apparatus that support breathing. People may get infected when they breathe in contaminated droplets (aerosols) and mist generated by artificial water systems. They may also get the infection when handling garden soils, compost and potting mixes.

It is most important to operate and maintain properly designed man-made water systems to prevent LD. The public may visit the pages below for more information:

• The CHP's LD page (This link will open in a new windowwww.chp.gov.hk/en/content/9/24/2117.html); and
• The Code of Practice for Prevention of LD of the Prevention of LD Committee, Hong Kong(This link will open in a new windowwww.emsd.gov.hk/emsd/eng/pps/oa_ld_pub_cp.shtml).
• The Housekeeping Guidelines for Cold and Hot Water Systems for Building Management(This link will open in a new windowwww.emsd.gov.hk/emsd/eng/pps/oa_ld_pub.shtml).