Confirmed local case of Japanese encephalitis

The Centre for Health Protection (CHP) of the Department of Health (DH) is  investigating a confirmed local case of Japanese encephalitis (JE), and hence urged the public to take precautions against mosquito-transmitted diseases.

The female patient aged 35, has developed fever, headache and vomiting since July 4 and sought medical consultation from private doctors. She attended the Accident and Emergency Department of Tuen Mun Hospital and was admitted for management on July 14. She is now afebrile in stable condition.

Her serum and cerebrospinal fluid specimens tested positive for antibodies against JE today upon testing by the CHP’s Public Health Laboratory Services Branch.

Initial enquiries revealed that the patient lives in Shap Pat Heung, Yuen Long and has occasional mosquito bites. Her home contacts have remained asymptomatic and would be put under medical surveillance. Investigations are ongoing.

Officers of the CHP will conduct home visits and surveys among neighbours of the patient’s residence for active case finding and arranging blood tests. A hotline of CHP (2125 1122) was set up for public enquiries which would operate till 9pm today and from 9am to 6pm tomorrow (July 22) onwards.

A health talk will be held in Tong Tau Po Tsuen, Yuen Long, this evening to deliver health advice to the public. Residents of Yuen Long District with JE symptoms are also advised to promptly seek medical attention.
The CHP will issue letters to doctors and hospitals to draw their attention to the case and enlist their support in early diagnosis, control and prevention of JE.

This is the second JE case 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 in the Mainland and Southeast Asia,” a spokesman for the CHP explained.

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 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 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.

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