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CHP investigates suspected case of Japanese encephalitis

     The Centre for Health Protection (CHP) of the Department of Health (DH) is today (July 8) investigating a suspected case of Japanese encephalitis (JE), and hence again urged the public to maintain strict environmental hygiene, mosquito control and personal protective measures both locally and during travel.

     "Although the case is now a suspected one, the patient had no recent travel history and the infection might be locally acquired. While pending laboratory confirmation, as a precautionary measure, we are working closely with the Food and Environmental Hygiene Department (FEHD) to assess and prevent any possible spread," a spokesman for the CHP said.

     According to the patient's family, the male patient, aged 55 with good past health, has presented with fever, drowsiness, slurring of speech and vomiting since July 4. He attended the Accident and Emergency Department of North District Hospital on July 6 and was admitted for management.

     The clinical diagnosis was meningoencephalitis and he has been in stable condition.

     His cerebrospinal fluid preliminarily tested positive for antibodies against JE upon screening test by the CHP's Public Health Laboratory Services Branch, pending laboratory confirmation tomorrow (July 9).

     Initial enquiries revealed that the patient had no travel history during the incubation period. His home contacts have remained asymptomatic and have been put under medical surveillance.

     The patient's local movements were mainly in the vicinity of his residence and workplace. He lives in Sheung Ma Tseuk Leng, Sha Tau Kok, New Territories, where he recalled mosquito bites. According to the Agriculture, Fisheries and Conservation Department, there are no registered pig farms within two kilometres radius from the patient's residence.

     "We immediately commenced epidemiological investigations and informed the FEHD for vector control, vector investigation and corresponding follow-up. Investigations are ongoing," the spokesman added.

     The CHP's hotline (2125 1133) for enquiries will operate until 10pm today and from 9am to 6pm tomorrow.

     To date, one local JE case has been reported to the CHP this year. Five (three local, two imported) were filed in 2014 while six (two local, three imported, one unclassified) were filed in 2013.

     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.

     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 of over one month, particularly in high-risk rural areas.

     The public may visit the pages below for more information:
* The CHP's JE page (;
* The DH's Travel Health Service (;
* The CHP's tips for using insect repellents (;
* The CHP Facebook Page (;
* The CHP YouTube Channel (; and
* The FEHD's Guidebook on Control and Prevention of Mosquito Breeding (

Ends/Wednesday, July 8, 2015
Issued at HKT 21:49


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