Four Legionnaires' disease cases reported; public urged to maintain water systems and follow health precautions.

DH announces latest situation regarding Legionnaires' disease cases

The Centre for Health Protection (CHP) of the Department of Health (DH) today (July 13) reported the latest number of Legionnaires' disease (LD) cases, and reminded the public of the importance of using and maintaining properly designed man-made water systems, adding that susceptible groups should strictly observe relevant precautions.

From July 5 to 12, the CHP recorded four LD cases, involving one nosocomial case (i.e. hospital-acquired) and three community-acquired cases. All of the patients, aged between 66 and 89, had underlying illnesses.

Community-acquired cases

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The details of the three community-acquired LD cases are as follows:

• a 66-year-old male living in North District;
• a 71-year-old male living in Sham Shui Po District; and
• a 72-year-old male living in Yuen Long District.

The CHP is conducting epidemiological investigations to identify the potential sources of infection and high-risk exposure. An initial investigation revealed that the three community-acquired cases are sporadic cases. No epidemiological linkages have been established between these cases and other confirmed cases previously recorded in Hong Kong.

Nosocomial cases

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Regarding the nosocomial case involving Hong Kong Sanatorium & Hospital announced on July 10, 16 water and environmental samples were collected from the patient's ward and the results of laboratory testing are pending.

As for the nosocomial case at Princess Margaret Hospital (PMH) announced by the CHP in late June, test results from the CHP's Public Health Laboratory Services Branch showed that, among 25 predisinfection water samples collected from the wards where the patient had been admitted, three collected from the Neurosurgery High Dependency Unit and one collected from the Intensive Care Unit tested positive for Legionella pneumophila serogroup 1 (Lp1) at levels ranging from 0.1 to 0.3 colony-forming units per millilitre (cfu/ml), exceeding the action level for water supply systems in high-risk areas of hospitals (i.e. 0.1 cfu/ml or above). The respiratory specimens of the patient and the above positive water samples were of the same sequence type of Lp1. All 15 environmental samples tested negative for Lp1. PMH has thoroughly disinfected the water supply systems of the concerned ward.

The CHP has provided the two hospitals concerned with health advice and medical surveillance recommendations, and will continue to closely monitor the implementation of these measures. The CHP will also continue to investigate and follow up on the nosocomial cases. Other patients who were hospitalised on the same floor or wards as the patients during the same period are undergoing medical surveillance. No additional LD cases have been identified among them so far.

As of July 11, 93 LD cases had been recorded this year. In 2025 and 2024, there were 167 and 135 LD 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; living in areas with old water systems, cooling towers or fountains; using electric water heaters, whirlpool spas or hot water spring spas; and recent stays in hotels or ships.

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, whirlpool spas, water fountains, humidifiers and home respiratory devices 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) or less 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:

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

The public may visit the CHP'sLD page, theCode of Practice for Prevention of LDand theHousekeeping Guidelines for Cold and Hot Water Systems for Building Managementof the Prevention of LD Committee, and the CHP'srisk-based strategyfor prevention and control of LD.

Additionally, as smokers and alcoholics are more susceptible to LD, the Government urge members of the public to quit smoking and avoid drinking. Members of the public may call the DH Integrated Smoking Cessation Hotline at 1833 183, which is answered by registered nurses who provide professional counselling and referral to a wide range of free smoking cessation services. The public may also visit the smoking cessation thematic website (www.livetobaccofree.hk) for more information on smoking cessation. The DH has also developed and promulgated the Alcohol Screening and Brief Intervention tool to primary healthcare service providers to facilitate the early identification and management of at-risk drinkers. For information on alcohol-related harm, please visit the DH'sChange for Health website.

Source: AI-found images

CHP investigates a case of human infection of rat Hepatitis E virus

The Centre for Health Protection (CHP) of the Department of Health today (July 13) is investigating a case of human infection of rat Hepatitis E virus (HEV). The CHP urged the public to maintain good personal, food and environmental hygiene, and to implement effective rodent prevention and control measures to prevent rat HEV infection.

Case details

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The case involves a 72-year-old male with underlying illnesses and weakened immunity. On July 9, during a follow-up visit to Queen Mary Hospital for his pre-existing condition, he was found to have abnormal liver function. His blood sample tested positive for rat HEV upon laboratory testing by the Public Health Laboratory Services Branch under the CHP. The patient remains in stable condition. He has not developed symptoms and did not require hospitalisation.

The CHP's epidemiological investigation revealed that the patient lives in Sham Shui Po District and primarily spends his time in the vicinity of Sham Shui Po and Tsim Sha Tsui districts. He had outbound travel with his family member from late May to early June (within the incubation period). He reported having no direct contact with rodents or rats, nor has seen any rats at his residence or places visited. The CHP does not rule out thatthe patient might have come into indirect contact with places or food contaminated by rats or their excreta during the incubation period, either locally or during outbound travel. His household contact (also his travel collateral) has no symptoms currently and has been put under medical surveillance.

Investigations into the source and route of infection are ongoing.

Although the place of infection cannot be ascertained at this stage, staff from the CHP and the Food and Environmental Hygiene Department (FEHD) have conducted site inspections of the patient's residence and the his routine activity areas to assess environmental hygiene conditions. Investigation staff detected minor signs of rodent activity in the refuse collection room of his residential building, on the streets around his residence, on the streets in the vicinity of his activity areas in Tsim Sha Tsui, as well as in the food premises he had visited. Apart from stepping up the cleansing and disinfection, as well asanti-rodent work in the public areas in the vicinity of the locations visited by the patient, the FEHD will serve a Notice of Elimination of Vermin under section 47 of the Public Health and Municipal Ordinance (Cap. 132) requesting the licensee of concerned food premises and owners' corporations of the concerned building to take appropriate actions within a specified timeframe to eliminate vermin in the concerned food premises and common parts of the building.

The CHP and the FEHD will continue to investigate and follow up on the case.

This is the second case of human infection of rat HEV recorded so far this year. In the past five years (from 2021 to 2025), Hong Kong recorded an average of zero to two cases of rat HEV per year.

Symptoms of rat hepatitis E

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Human cases of rat hepatitis E virus infection affected mostly immunocompromised persons. Most cases were asymptomatic, while symptomatic patients reported mild symptoms, such as fatigue, abdominal pain and loss in appetite. It is less likely for patients with rat HEV infection to develop jaundice compared to HEV infected patients.

Prevention

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The possible routes of transmission of rat HEV to humans include ingestion of food or water contaminated by rodents or their excreta, exposure to environments or objects contaminated by rodents or their excreta and direct contact with rodents or their excreta. The HEV that usually causes human infection is mainly transmitted through the fecal-oral route.

To prevent Hepatitis E infection, the public should maintain good personal, food and environmental hygiene. For example, they should wash their hands thoroughly before eating, store food properly or in the refrigerator, avoid leaving food at room temperature for a long time, and use 1:99 diluted household bleach for general household cleaning and disinfection as household detergents may not kill HEV.

The Five Keys to Food Safety should be adopted when handling food, i.e. Choose (choose safe raw materials), Clean (keep hands and utensils clean), Separate (separate raw and cooked food), Cook (cook thoroughly) and Safe Temperature (keep food at a safe temperature), to prevent food-borne diseases.

In general, rodents (such as rats) can transmit multiple diseases to humans, both directly and indirectly. The public is advised to take the following measures:

• Eliminate sources of food and nesting places for rodents in the living environments. Store food in covered containers and handle pet food properly to prevent it frombecoming food for rodents;
• Store all refuse and food remnants in dustbins with well-fitted covers. Dustbins must be emptied at least once a day;
• Keep premises, especially refuse rooms and stairways, clean. Avoid accumulation of articles;
• Inspect all flower beds and pavements regularly for signs of rodent infestation; and
• Avoid the high-risk activities below to reduce rodent contact:

- Avoid contact with rodents and areas contaminated by rodent excreta;

- Avoid handling rodents with bare hands;

- Wash hands with liquid soap and water immediately after handling animals, and disinfect contaminated areas; and

- If a wound appears, clean the broken skin immediately and cover it properly with waterproof adhesive dressings.

Rodent control requires co-operation from all sectors of society. The CHP urged the public to strengthen rodent prevention and control measures and co-operate with government's efforts to reduce the risk of rat HEV transmission.

CHP investigates a case of human infection of rat Hepatitis E virus Source: HKSAR Government Press Releases