DH investigates Legionnaires’ Disease cluster
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The Centre for Health Protection (CHP) of the Department of Health today (March 5) announced that it is investigating a cluster of Legionnaires’ disease (LD) cases involving four members of a tour group to Qingyuan and Foshan. The CHP appealed to those who participated in the package tours organised by the Sino Step Travel Services to Qingyuan and Foshan from February 20 to 28 to contact the CHP for health assessment and medical surveillance.
An epidemiological investigation was launched immediately after the CHP received a notification that a 77-year-old female was infected with LD. It was subsequently found that two males and one female who had joined the same tour group were also infected with LD. The four patients involved two males and two females, who aged between 61 and 77.
The four persons concerned joined the above tour groups to Qingyuan and Foshan during the incubation period (travel dates: February 20 to 22; tour code: LB3280). Initial investigation revealed that they did not have common local exposure history. Therefore, they are believed to have become infected during the outbound tour and were classified as imported cases.
The Sino Step Travel Services organised two other tours (both with tour code LB3280) with the same itineraries and hotel accommodation recently, held from February 21 to 23 and February 26 to 28 respectively. For the sake of prudence, the CHP is actively contacting the participants of the three tour groups to follow up on their health conditions. The CHP also appealed to them to call the CHP’s hotline (telephone number: 2125 2670) for follow up and medical surveillance. The hotline will be operating from tomorrow (March 6) to March 14, from 9am to 5pm from Monday to Friday, and from 9am to 1pm on Saturday and Sunday. They should seek medical advice immediately if they have a fever or feel unwell.
The CHP has informed the Travel Industry Authority and reported the case to the health authorities of Guangdong. Epidemiological investigations are still in progress.
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; 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.
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; 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.