Update on chikungunya fever
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Latest case information
The two cases are from the same family, involving a 50-year-old male and his 8-year-old daughter, living in Sai Kung District. Initial investigations revealed that both patients travelled to Dhaka, the capital of Bangladesh, between July 20 and August 10, and could not confirm whether they had a history of mosquito bites. The male patient developed fever on August 1 while he was in Bangladesh, and joint pain in the limbs the next day (August 2). He sought medical attention from an outpatient clinic there on August 3 and did not require hospitalisation. He was informed that his blood sample tested positive for the CF virus upon laboratory testing. His fever had subsided before returning to Hong Kong on August 10, but due to swollen joints, he attended a private hospital on August 12. As the patient was afebrile before arriving in Hong Kong (i.e. prior to the ninth day after the onset of symptoms), he was not infectious to mosquitoes upon returning to Hong Kong and did not require hospitalisation.
For the girl, she developed fever, cough and fatigue on August 12 and attended a private hospital yesterday (August 13). She was admitted for treatment in a mosquito-free environment and is in stable condition.
The two patients' blood samples tested positive for the CF virus upon laboratory testing. Since they stayed in Bangladesh during the whole incubation period, the CHP considered that they were infected during travel, and the cases were classified as imported cases. Their three household contacts (including two travel collaterals who had been to Bangladesh) are currently asymptomatic and under medical surveillance. The CHP's epidemiological investigations are ongoing, and it has reported the cases to the health authority of Bangladesh.
So far this year, Hong Kong has recorded a total of eight confirmed CF cases. All are imported cases. From 2016 to 2019, Hong Kong recorded between one and 11 imported cases annually.
Continuously strengthening prevention and control
The Food and Environmental Hygiene Department (FEHD) is conducting vector investigations and targeted mosquito control operations and will intensify mosquito prevention and control measures at the residence of the two patients, as well as locations visited after the onset of symptoms. These measures include:
- carrying out intensive fogging in the scrubby areas within a 250-metre radius of the relevant locations to kill adult mosquitoes;
- carrying out inspection 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 CHP's Port Health Division continues to step up inspections at boundary control points and to remind 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-up when necessary.
To raise awareness among the elderly about preventing CF, the Visiting Health Teams under the Elderly Health Service of the DH have been advising the elderly on CF prevention and travel health at health talks conducted at District Elderly Community Centres and Neighbourhood Elderly Centres. They have also reminded residential care homes for the elderly to enhance mosquito control measures. The DH's Maternal and Child Health Centres, Student Health Service Centres and Special Assessment Centres also advise pregnant women, infant carers and students on symptoms and preventive measures of CF.
To strengthen support for ethnic minority communities, essential information on CF has also been translated into 10 ethnic minority languages (namely Hindi, Nepali, Urdu, Thai, Bahasa Indonesia, Tagalog, Vietnamese, Punjabi, Sinhala and Bengali) and uploaded to the CHP website.
The Controller of the CHP, Dr Edwin Tsui reminded members of the public that currently, there are no rapid test products on the market that have been certified by international health authorities for public use in self-testing for CF. They should promptly seek medical advice if they suspect they are infected with CF and should not conduct testing on their own as this may delay proper clinical treatment. He also urged the public not to self-medicate, particularly with aspirin or non-steroidal anti-inflammatory drugs (such as ibuprofen), as these drugs may cause serious side effects, for example, increasing the risk of haemorrhage. In general, children should not take medications containing aspirin to relieve fever or other symptoms because it may lead to "Reye's syndrome", a serious and potentially fatal complication.
He also added that members of the public should adopt precautions during the rainy season against mosquito-borne diseases. Proper use of DEET-containing insect repellents or other effective active ingredients can effectively 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.
In addition, the FEHD 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/Thursday, August 14, 2025
Issued at HKT 19:28
Issued at HKT 19:28
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