Update on chikungunya fever
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Latest surveillance data
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Regarding the imported case involving a 63-year-old male residing in Kwai Tsing District that the CHP announced last week, the CHP has completed the genome analysis of this patient's sample. The results showed that the genetic sequence was identical to those of two previously announced local cases (a 63-year-old male and a 49-year-old female residing in Tsing Yi), indicating that the three patients shared a common source of infection. However, it is differed from the genetic sequences of other local or imported CF cases. Their activities overlapped in Tsing Yi North, primarily in the Tsing Yi town centre and the Tsing Yi Nature Trails. Based on epidemiological investigation and genome analysis, the CHP now reclassified this case as locally acquired. The cluster involves a total of three patients. Since late November, relevant government departments have strengthened mosquito-borne disease prevention and control measures in response to the cases in Tsing Yi, and conducted active contact tracing in the area. Therefore, this local case has no substantial impacts on the current overall risk assessment.
Of the 77 confirmed CF cases in Hong Kong this year, nine were local, and the rest were imported.
Government's comprehensive follow-up actions
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Regarding the local case involving a 23-year-old female living in Sheung Wan announced yesterday (December 3), the epidemiological investigation is ongoing.
The CHP urged the members of the public residing and working in Queen's Road West (near Morrison Street and Hollywood Road) who experienced a fever, rash or joint pain on or after November 15 to seek medical advice or contact the CHP immediately. The CHP officers continued to reach out to individuals in the aforementioned locations to remind individuals to be aware of relevant symptoms and to maintain good environmental hygiene in their households.
As of 5pm today, the CHP has conducted assessments for over 1 100 individuals residing or working in the higher-risk district through the health consultation booth at the main entrance of the Sheung Wan Civic Centre, its enquiry hotline (2125 2373) and questionnaire surveys. One individual with mild symptoms has been arranged to undergo blood tests. Result is pending.
On the other hand, as some confirmed CF cases have reportedly been bitten by mosquitoes while hiking along the Tsing Yi Nature Trails, the CHP considered the trails to be a higher-risk area. As a precautionary measure, the CHP continued to urge individuals who have recently visited the Tsing Yi North area or hiked along the Tsing Yi Nature Trails to seek medical attention as soon as possible if they develop relevant symptoms and to call the aforesaid enquiry hotline.
Specifically targeting confirmed cases who visited the Tsing Yi Nature Trails or the surrounding area, the FEHD has been conducting intensive fogging operations to eliminate adult mosquitoes along the hiking trails. At suitable locations, large ultra-low volume foggers have been deployed, and robot dog is being put on trial to enhance operational effectiveness. The FEHD has also set up new mosquito trapping devices, cleared discarded containers and garbage that could bring stagnant water, and applied larvicide oil or larvicides in areas with stagnant water that cannot be removed immediately. Pamphlets have been also distributed to hikers in the area, urging citizens to be vigilant against mosquito infestations. The FEHD has earlier requested the relevant departments to strengthen efforts in eliminating potential mosquito breeding sites along the Tsing Yi Nature Trails. The FEHD also held meetings of the inter-departmental task forces on anti-mosquito work across districts, to discuss the latest developments regarding the situation and plan accordingly to coordinate relevant departments and stakeholders in strengthening mosquito prevention and control measures in areas under their purview.
Furthermore, the FEHD and relevant departments have comprehensively enhanced the mosquito control operations in Hong Kong since July this year, and this has continued. Among these, the FEHD has conducted vector investigations and targeted mosquito control operations against the imported and local cases. In light of the local cases, the FEHD has immediately conducted follow-up actions, including:
- 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.
The abovementioned measures will be continued. Furthermore, the Government will further enhance the mosquito control efforts in addition to the existing measures.
Preventive measures to be taken by the public
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Members of the public should use DEET-containing insect repellents or other effective active ingredients properly to 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 empty cans and lunch boxes. The FEHD also advises members of the public and property management agencies 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/Thursday, December 4, 2025
Issued at HKT 19:47
Issued at HKT 19:47
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