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CHP investigating imported case of Japanese encephalitis

     The Centre for Health Protection (CHP) of the Department of Health (DH) is today (August 14) investigating an imported case of Japanese encephalitis (JE) affecting a girl aged 4 and urged the public to take precautions against mosquito-transmitted diseases.

     The patient, who had good past health, lives in Shenzhen. She travelled to Henan from July 15 to 19 and came to Hong Kong on July 26. She has presented with fever and headache since July 25. She was admitted to Tseung Kwan O Hospital on July 26 and developed convulsions after admission. Her condition was stable and she was discharged on August 6. Her home contacts remain asymptomatic. Investigation is ongoing.

     Her serum samples tested positive for antibodies against JE, a viral disease transmitted by the bite of infected mosquitoes. The test was done by the CHP's Public Health Laboratory Services Branch.

     To date, five JE cases (three local and two imported) have been reported to the CHP this year. 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 waterlogged fields, marshes, ditches and small stagnant collections of water around cultivated fields. The mosquitoes become infected by feeding on pigs and wild birds infected with the JE virus, and then transmit the virus to humans and animals during the feeding process. JE is endemic on the Mainland and in Southeast Asia," a spokesman for the CHP said.

     Most JE virus infections are mild without apparent symptoms other than fever with headache. More severe infections are clinically characterised by the quick onset of headache, high fever, neck stiffness, impaired mental state, coma, tremors, occasional convulsions (especially in infants) and paralysis.

     To avoid 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.

     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 a travel health consultation with a 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 stays 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/Thursday, August 14, 2014
Issued at HKT 18:58


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