Update on mosquito-borne diseases, chikungunya fever and dengue fever
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Chikungunya fever
As of 5pm today, one new case of CF had been recorded.
The case involves a 44-year-old female living in Yuen Long District. A preliminary investigation revealed that she visited Kweiping in the Guangxi Zhuang Autonomous Region between September 20 and October 19. She has developed a fever, joint pain and rash since October 22, and sought medical attention at the Accident and Emergency Department of Pok Oi Hospital yesterday (October 23). Her blood sample tested positive for the chikungunya virus upon laboratory testing. The patient is now in stable condition and is being arranged for treatment in a mosquito-free environment.
Since the patient stayed in the Guangxi Zhuang Autonomous Region during her incubation period, the CHP considered that she was infected during travel. The case was classified as imported. The CHP's epidemiological investigation is ongoing, and it has reported the case to the health authority of the Mainland.
So far this year, Hong Kong has recorded a total of 44 confirmed CF cases. All are imported cases. Among which, a patient passed away, while conditions of other patients are mild.
Severe symptoms and deaths caused by CF are extremely rare, with a mortality rate of less than one in 1 000. The occurrence of severe complications is mostly related to the patients' underlying health conditions. Elderly persons (particularly those aged 65 or above), young children (particularly infants under 1 year old), pregnant women and persons with chronic illnesses (such as hypertension, diabetes or heart disease) are at higher risk of developing complications after contracting CF and may require a longer recovery period. Therefore, members of the public (especially the abovementioned high-risk groups) are advised to seek medical advice promptly if they develop relevant symptoms, particularly a fever, sudden severe joint pain and skin rash, after visiting areas affected by CF.
Since the beginning of 2025, and as of September 30, a total of 445 271 suspected and confirmed CF cases and 155 CF-related deaths have been reported in 40 countries/territories. Cases have been reported in the Americas, Africa, Asia, and Europe. CF outbreaks currently occur in many countries worldwide. Members of the public should check the situation of the destinations before travelling abroad.
Dengue fever
From October 17 to yesterday (October 23), the CHP recorded one imported DF case. The patient had travelled to Yunfu in Guangdong Province during the incubation period.
As of yesterday, 50 imported DF cases have been recorded so far this year. A total of 161 cases of DF were recorded in 2024, including 156 imported and five local cases.
According to the World Health Organization (WHO), the global incidence of DF has markedly increased over the past two decades, posing a substantial public health challenge. In 2024, the WHO recorded over 14 million cases, which was a record number. From January to July 2025, over 4 million cases and over 3 000 DF-related deaths have been reported in 97 countries/territories.
DF is prevalent in many neighbouring tourist destinations. Indonesia, India, Malaysia, Thailand and Vietnam have each recorded over 40 000 cases so far this year. Singapore has also recorded over 3 500 cases. Meanwhile, according to the Guangdong Provincial Center for Disease Control and Prevention, Guangdong Province has recorded 2 181 locally infected cases so far this year. A total of 383 cases were recorded in a week between October 6 to 12, with the highest number of cases recorded in Shenzhen, Guangzhou, Chaozhou, Jiangmen and Dongguan.
Detailed information on the latest DF situation in Hong Kong, as well as neighbouring and overseas countries and areas, has been uploaded to the CHP website.
Continuously strengthening prevention and control
The Food and Environmental Hygiene Department (FEHD) continues to conduct vector investigations and targeted mosquito control operations, and intensify mosquito prevention and control measures at the residences of recently confirmed patients of DF and CF, as well as at locations visited after the onset of symptoms. These measures include:
- carrying out intensive fogging in scrubby areas within a 250-metre radius of the relevant locations to kill adult mosquitoes;
- carrying out inspections of the locations, removing stagnant water, applying insecticides and disposing of abandoned water containers every week with a view to preventing mosquito breeding; and
- enhancing public education efforts through organising health talks, setting up mobile education stations, and distributing publicity leaflets.
Additionally, the CHP's Port Health Division continues to step up inspections at boundary control points and reminds cross-boundary public transport operators and other relevant parties to ensure good environmental hygiene and effective implementation of anti-mosquito measures. Furthermore, staff members of the Port Health Division distribute leaflets to travellers, conduct temperature screenings for inbound travellers, conduct health assessments for travellers with fever or related symptoms and refer them to hospitals for follow-ups when necessary.
Proper use of DEET-containing insect repellents or other effective active ingredients can prevent mosquito bites, but the following precautions should be taken when using them:
- read the label instructions carefully first;
- apply right before entering an area with a risk of mosquito bites;
- apply on exposed skin and clothing;
- use DEET of up to 30 per cent for pregnant women and up to 10 per cent for children (For children who travel to countries or areas where mosquito-borne diseases are endemic or epidemic and where exposure is likely, those aged 2 months or above can use DEET-containing insect repellents with a DEET concentration of up to 30 per cent);
- apply sunscreen first, then insect repellent;
- reapply only when needed and follow the instructions; and
- in addition to DEET, there are other insect repellents available on the market containing different active ingredients, such as IR3535 and picaridin. When using any insect repellent, the public should follow the usage instructions and precautions on the product label.
The FEHD also appeals to members of the public to continue to stay alert and work together to carry out mosquito prevention and control measures early, including inspecting their homes and surroundings to remove potential breeding grounds, changing water in vases and scrubbing their inner surfaces, removing water in saucers under potted plants at least once a week, and properly disposing of containers such as soft drink cans and lunch boxes. The FEHD also advises members of the public and estate management bodies to keep drains free of blockage and level all defective ground surfaces to prevent the accumulation of water. They should also scrub all drains and surface sewers with an alkaline detergent at least once a week to remove any mosquito eggs.
The public should call 1823 in case of mosquito problems, and may visit the following pages for more information: the CF page of the CHP and the Travel Health Service, the latest Travel Health News, tips for using insect repellents, and the CHP Facebook Page, Instagram Account and YouTube Channel, and also the Mosquito Prevention and Control dedicated page of the FEHD.
Ends/Friday, October 24, 2025
Issued at HKT 19:30
Issued at HKT 19:30
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