Update on cases of Legionnaires’ disease
The Centre for Health Protection (CHP) of the Department of Health today (July 18) reported the latest number of cases of Legionnaires' disease (LD), and stressed the importance of using and maintaining properly designed man-made water systems, adding that susceptible groups should strictly observe relevant precautions.
From July 9 to 15, six LD cases were reported:
- A male patient, aged 89 with underlying illnesses, who lived in Block 3, Elegance Garden, Tai Po. It was classified as a community-acquired case. The patient passed away on July 13;
- A male patient, aged 64 with underlying illnesses, who lives in Block 2, Lei Muk Shue Estate, Tsuen Wan. It was classified as a community-acquired case;
- A male patient, aged 87 with underlying illnesses, who lives in Lee Cheung House, Shun Lee Estate, Kwun Tong. It was classified as a community-acquired case;
- A female patient, aged 71 with underlying illnesses, who lives in Lai Kwai House, Lai Kok Estate, Sham Shui Po. It was classified as a community-acquired case;
- A male patient, aged 70 with underlying illnesses, who lives in Chui Ho House, Sheung Chui Court, Tsuen Wan. He had a travel history during the incubation period; and
- A male patient, aged 58 with underlying illnesses, who lives in Kam Shing House, Kam Tai Court, Ma On Shan. It was classified as a community-acquired case.
"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 July 15, 54 LD cases had been reported this year. In 2022 and 2021, there were 80 and 69 cases respectively.
"Men, people aged over 50, smokers, alcoholics and persons with weakened immunity are more susceptible to LD. Some situations may also increase the risk of infection, including poor maintenance of water systems leading to stagnant water; living in areas with old water systems, cooling towers or fountains; using electric water heaters, whirlpools and spas or hot water spring spas; and recent stays in hotels or vessels," the spokesman said.
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 become infected when they breathe in contaminated droplets (aerosols) and mist generated by artificial water systems, or when handling garden soil, compost and potting mixes.
Immunocompromised persons should:
- 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. Also, 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 should observe the health advice below:
- Observe personal hygiene;
- Do not smoke and avoid alcohol consumption;
- Strainers in water taps and shower heads should be inspected, cleaned, descaled and disinfected regularly or at a frequency recommended by the manufacturer;
- 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 (µm) and the filter needs to be changed periodically according to the manufacturer's recommendations;
- Drain and clean water tanks of buildings at least quarterly;
- Drain or purge for at least one minute 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 doctors' professional advice regarding the use and maintenance of home respiratory devices and use only sterile water (not distilled or tap water) to clean and fill the reservoir. Clean and maintain the device regularly according to the manufacturer's instructions. After cleaning/disinfection, rinse the device with sterile water, cooled freshly boiled water or water filtered with 0.2 µm 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:
- Wear gloves and a face mask;
- Water gardens and compost gently using low pressure;
- Open composted potting mixes slowly and make sure the opening is directed away from the face;
- Wet the soil to reduce dust when potting plants; and
- Avoid working in poorly ventilated places such as enclosed greenhouses.
​The public may visit the CHP's LD page, the Code of Practice for Prevention of LD and the Housekeeping Guidelines for Cold and Hot Water Systems for Building Management of the Prevention of LD Committee, and the CHP's risk-based strategy for prevention and control of LD.