Update on cases of Legionnaires' disease
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From December 18 to 24, two community-acquired LD cases were reported. They are:
- A male patient, aged 54, who lives in Tat Kwai House, Po Tat Estate, Sau Mau Ping; and
- A male patient, aged 65 with underlying illnesses, who lives in Ngan Yat House, Ngan Wan Estate, Mui Wo.
"Epidemiological investigations are ongoing to identify potential sources of infection, high-risk exposure and clusters, if any," a spokesman for the CHP said.
To update on investigations into an LD case in Pok Oi Hospital (POH) announced on December 15 and 23, further laboratory investigations by the CHP's Public Health Laboratory Services Branch showed that 10 out of 11 water samples tested positive for legionella, with a level from 3.0 to 72.4 colony-forming units per millilitre (cfu/ml).
Based on the strategy recommended by the CHP's Scientific Committee on Emerging and Zoonotic Diseases in effect since January 1 this year, the total legionella count of these 10 positive samples was higher than the action level of water systems in low-risk areas of hospitals, i.e. one cfu/ml or above. They are:
- Four from the shower of the assisted bath room used by the patient from 3.0 to 17.2 cfu/ml;
- Four from the water taps in the toilet used by the patient from 6.2 to 72.4 cfu/ml; and
- Two from the water tap of the patient's cubicle in the ward of 14.6 and 18.2 cfu/ml respectively.
"The CHP and the Electrical and Mechanical Services Department were informed that disinfection of water systems concerned had been conducted from December 24 to 26. Medical surveillance in the ward to which the patient was admitted has been enhanced in collaboration with POH. No additional cases have been identified thus far. We will maintain close liaison with POH to monitor the latest developments. Epidemiological investigations are ongoing," the spokesman said.
As of December 24, a total of 75 LD cases, including 73 community-acquired cases and two institutional cases (including one death), 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:
- 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.
More information is available on these 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/Wednesday, December 28, 2016
Issued at HKT 17:55
Issued at HKT 17:55
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Related Links
CHP investigates case of Legionnaires' disease in hospital
Update on investigation into case of Legionnaires' disease in hospital
Latest update on Legionnaires' disease case in Pok Oi Hospital
Latest recommendations of Scientific Committee on strategy for prevention and control of Legionnaires' Disease