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Update on confirmed local case of Japanese encephalitis

     The Centre for Health Protection (CHP) of the Department of Health (DH) today (June 24) provided an update on its investigation into a confirmed local case of Japanese encephalitis (JE), and hence urged the public to take precautions against mosquito-transmitted diseases.

     Subsequent to the case which was laboratory confirmed by the CHP¡¦s Public Health Laboratory Services Branch (PHLSB) on June 17, a total of nine blood samples were collected from persons living in the vicinity between June 17 and 20 through active case finding. Upon laboratory testing, a blood specimen collected from a 55-year-old woman was tested positive for antibodies against JE by the PHLSB today.

     Initial investigation has revealed that the woman, who lives in Tin Yuet Estate, Tin Shui Wai, has remained asymptomatic all along.  Her home contacts have remained asymptomatic. She is not a close contact with the local case.  Investigations are ongoing.

     Officers of CHP have conducted surveys among neighbours of the woman's residence for active case finding. A hotline of CHP (2125 1122) has been set up since June 17 for public enquiries which would operate daily between 9am and 6pm from Monday to Friday.

     The CHP had conducted four health talks last week and another health talk has been conducted in Tin Ching Community Hall, Tin Shui Wai, this evening to deliver health advice to the public. Residents of Yuen Long District, including those in Tin Shui Wai, with JE symptoms are also advised to promptly seek medical attention.

     As regards the first JE case reported to the CHP this year, the 26-year-old female patient was discharged on June 19.

     As the 55-year-old woman has been asymptomatic all along, hence it is not classified as a confirmed case. The number of JE case reported to the CHP this year remains at one. Six cases (two local, three imported and one unclassified) were reported in 2013 while three (one local and two imported) were filed in 2012.

     "JE is a viral disease transmitted by the bite of infected mosquitoes. Culex tritaeniorhynchus (Culicine mosquito) is the principal vector of JE and is nocturnal. It mainly breeds in relatively large water bodies such as waterlogged fields, marshes, ditches and pools. The mosquitoes become infected by feeding on pigs and wading birds infected with the JE virus, and then transmit the virus to humans and animals during the feeding process. Human is the dead end host and the disease is not directly transmitted from person-to-person. JE is endemic in the Mainland and Southeast Asia," a CHP spokesman explained.

     The spokesman added that most JE virus infections are mild without apparent symptoms other than fever with headache.  Approximately 1 in 250 infections results in severe disease characterized by rapid onset of high fever, headache, neck stiffness, disorientation, coma, seizures, spastic paralysis and death. Through active case finding, it is expected that there may be cases of recent infections with mild or no symptoms.

     To prevent contracting JE, members of the public, particularly those living in rural areas, are reminded to take heed of the following preventive measures, especially after dark:

* Wear loose, light-coloured long-sleeved clothes and trousers;
* Use effective insect repellents containing DEET over exposed parts of the body and clothing when outdoors; and
* Use mosquito screens or nets in rooms which are not air-conditioned.

     The public is also reminded to take the following preventive measures:

* Ensure continuous water flow in waterlogged fields by installing devices such as water pumps/water gates and removing stagnant water regularly;
* Inspect water-cultivation areas and animal farms frequently;
* Eliminate stagnant water in surface channels; and
* Remove water in containers for animals after feeding and cover the containers properly after use.

     Travellers to endemic areas of JE should take the following precautions:

* Avoid outdoor exposure to mosquito bites at dusk and dawn, especially in rural areas, when mosquitoes spreading this virus are most active;
* Apply effective insect repellents containing DEET over exposed parts of the body and clothes; and
* Consider vaccination and arrange travel health consultation with doctor to determine the need for vaccination and vector preventive measures at least six weeks before departure to endemic areas in Asia or the Western Pacific for staying over one month, particularly in high-risk rural areas.

     The public may visit the CHP's JE page ( or that of the DH's Travel Health Service ( for further information on JE and outbreaks in other areas.

     "Vector-borne diseases" is the theme of this year's World Health Day (WHD) of the World Health Organization. The public may visit the CHP's WHD Page ( for more information.

Ends/Tuesday, June 24, 2014
Issued at HKT 21:57


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