Case of Japanese encephalitis under CHP investigation

     The Centre for Health Protection (CHP) of the Department of Health (DH) is today (July 16) investigating a confirmed case of Japanese encephalitis (JE) affecting a 59-year-old man and hence urged the public to take precautions against mosquito-transmitted diseases.

     The patient was admitted to Tuen Mun Hospital on June 20 because of fever and decreased general condition. His consciousness deteriorated the following day (June 21) and he is currently in critical condition.

     Upon laboratory testing, both his serum and cerebrospinal fluid samples tested positive for antibodies against JE. JE is a viral disease transmitted by the bite of infected mosquitoes.

     The patient lives in Tin Shui Wai. His home contact remained asymptomatic and has been put under medical surveillance. The CHP's investigation is proceeding.

     Officers of the CHP have conducted home visits and surveys among neighbours of the patient's residence for active case finding and arranging blood tests. A hotline on 2125 1122 has been set up for public enquiries and will operate till 9pm today and from 9am to 6pm from July 17 to 19.

     A health talk was delivered and another one will be held in Tin Ching Community Hall, Tin Shui Wai, on July 18 to provide the public with health advice. Residents of Yuen Long District with JE symptoms are also advised to promptly seek medical attention.

     This is the first JE case reported to the CHP this year. Three cases were reported in 2012 while one was reported in 2011. Locally, no cases were reported from 2008 to 2010.

     A CHP spokesman explained that 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 in the Mainland and Southeast Asia.

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

     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 long-sleeved clothes and trousers;
* Use effective insect repellents containing DEET over exposed parts of the body 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 that should be completed at least 10 days 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 website ( for more information on JE and that of the DH's Travel Health Service ( for further information on JE vaccination and outbreaks in other areas.

Ends/Tuesday, July 16, 2013
Issued at HKT 16:35