The Centre for Health Protection (CHP) of the Department of Health today (September 26) reported the latest number of cases of Legionnaires' disease (LD) in Hong Kong, and stressed the importance of using and maintaining properly designed man-made water systems, and that susceptible groups should strictly observe relevant precautions.

     From September 11 to 24, one community-acquired LD case affecting a female patient aged 85 with underlying illnesses was reported. She was a visitor and stayed in 28 Kin Chuen Street, Kwai Chung, for one day within the incubation period.

     "Epidemiological investigations are ongoing to identify potential sources of infection, high-risk exposure and clusters, if any," a spokesman for the CHP said.

     As of September 24, a total of 47 LD cases, including 46 community-acquired cases and one institutional death case, had been reported in 2016. In 2015 and 2014, there were 66 and 41 cases respectively.

     Legionellae 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 soil, compost and potting mixes.

     Persons with weakened immunity should strictly observe the health advice below:
 

• Use sterile or boiled water for drinking, tooth brushing and mouth rinsing;
• Avoid using humidifiers, or other mist- or aerosol-generating devices. A shower may also generate small aerosols; and
• If using humidifiers, or other mist- or aerosol-generating devices, fill the water tank with only sterile or cooled freshly boiled water, and not water directly from the tap. In addition, clean and maintain humidifiers/devices regularly according to manufacturers' instructions. Never leave stagnant water in a humidifier/device. Empty the water tank, wipe all surfaces dry, and change the water daily.

     The public, including susceptible groups, should take heed of the general precautions against LD below:
 

• Observe personal hygiene;
• Do not smoke and avoid alcohol;
• Remove strainers in water taps and shower heads quarterly for cleaning;
• If a fresh water plumbing system is properly maintained, it is not necessary to install domestic water filters. Use of water filters is not encouraged as clogging occurs easily, which can promote growth of micro-organisms. In case water filters are used, the pore size should be 0.2 micrometres and they need to be changed periodically;
• Drain and clean water tanks of buildings at least quarterly;
• Drain or purge for at least one minute the infrequently used water outlets (e.g. water taps, shower heads and hot water outlets) and stagnant points of the pipework weekly or before use;
• Seek and follow medical advice regarding the use and maintenance of home respiratory devices and use only sterile (not distilled or tap) water to clean and fill the reservoir. Clean and maintain the device regularly according to manufacturer's instructions. After cleaning/disinfection, rinse the device with sterile water, cooled freshly boiled water or water filtered with 0.2-micrometre filters. Never leave stagnant water in the device. Empty the water tank, keep all surfaces dry, and change the water daily; and
• When handling garden soil, compost and potting mixes:

1. Water gardens and compost gently using low pressure;
2. Open composted potting mixes slowly and make sure the opening is directed away from the face;
3. Wet the soil to reduce dust when potting plants; and
4. Avoid working in poorly ventilated places such as enclosed greenhouses.

     More information is available on the following pages: the CHP's LD page, the Code of Practice for Prevention of LD of the Prevention of LD Committee, the Housekeeping Guidelines for Cold and Hot Water Systems for Building Management, and the CHP's risk-based strategy for prevention and control of LD.

Ends/Monday, September 26, 2016
Issued at HKT 15:07

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