CHP investigates first case of Japanese encephalitis in 2016

     The Centre for Health Protection (CHP) of the Department of Health (DH) tonight (July 19) reported the first case of Japanese encephalitis (JE) in 2016, and again urged the public to maintain strict environmental hygiene, mosquito control and personal protective measures both locally and during travel.

     "As the patient had both travel history and local movements during the incubation period (IP), it cannot be ruled out at this stage that the case was locally acquired. As a precautionary measure, we are working closely with the Food and Environmental Hygiene Department (FEHD) to assess and prevent any possible spread of infection," a spokesman for the CHP said.

     The female patient, aged 22 with good past health, has developed fever, headache and neck pain since July 10. She was admitted to Queen Elizabeth Hospital on July 13 for management and has all along been in stable condition.

     Her cerebrospinal fluid tested positive for immunoglobulin M (IgM) antibodies against JE upon testing by the CHP's Public Health Laboratory Services Branch.

     Initial enquiries revealed that the patient had travelled to Thailand and Myanmar from June 19 to 26. According to the patient, travel collaterals have remained asymptomatic so far.

     Locally, the patient lives in a flat on Maidstone Road, To Kwa Wan, and home contacts who have remained asymptomatic are put under medical surveillance. She mainly stayed at home while in Hong Kong. She could not recall mosquito bites during the IP.

     "Epidemiological investigations are ongoing. We have informed the FEHD and the Agriculture, Fisheries and Conservation Department for vector investigation. Health education in the vicinity where the patient frequented will follow," the spokesman added.

     Officers of the CHP have conducted site visit and field investigation by questionnaire surveys at the patient's residence for active case finding and arranging blood tests. Joint health talks with the FEHD will be held to deliver health advice to residents and the public.

     Persons who have been to the vicinity of Maidstone Road with JE symptoms should call the CHP's hotline (2125 1133) for laboratory investigation or referral to hospital as appropriate. It will operate from 9am to 6pm tomorrow (July 20).

     This is the first JE case reported to the CHP this year. Two (one local, one unclassified) and five (three local, two imported) were filed in 2015 and 2014 respectively.

     JE is a mosquito-borne disease caused by the JE virus, which is transmitted by the bite of infected mosquitoes. The principal type of mosquito which transmits JE is called Culex tritaeniorhynchus. JE mainly occurs in rural and agricultural areas of Asia and the Western Pacific.

     The infected mosquito transmits JE virus to humans and animals during biting. The mosquitoes breed where there is abundant water such as rice paddies and become infected by feeding on pigs and wild birds infected with JE virus. JE is not directly transmitted from person to person.

     Symptoms usually start at around four to 14 days after being infected. Mild infections may occur without apparent symptoms other than fever with headache. More severe infection is marked by quick onset of headache, high fever, neck stiffness, impaired mental state, coma, tremors, convulsions (especially in children) and paralysis.

     There is no specific treatment for JE. Supportive therapy is indicated. The case fatality rate can be as high as 30 per cent among those with symptoms. Of those who survive, 20 to 30 per cent suffer permanent intellectual, behavioural or neurological problems such as paralysis, recurrent seizures or inability to speak.

     To prevent contracting JE, one should take general measures to prevent mosquito bites and avoid going to rural areas from dusk till dawn when the mosquitoes spreading this virus are most active. People planning to travel to areas in which JE is endemic should take special note. The public should:
  • Wear loose, light-coloured, long-sleeved tops and trousers, and use DEET-containing insect repellent on exposed parts of the body and clothing;
  • Take additional preventive measures when engaging in outdoor activities:
  1. Avoid using fragrant cosmetics or skin care products;
  2. Re-apply insect repellents according to instructions;
  • Special notes when travelling abroad:
  1. If going to affected areas, arrange a consultation with doctor at least six weeks before the trip, and have extra preventive measures to avoid mosquito bite;
  2. During the trip, if travelling in endemic rural areas, carry a portable bed net and apply permethrin (an insecticide) on it. Permethrin should not be applied to skin. Seek medical attention promptly if feeling unwell; and
  3. Travellers if feeling unwell, such as fever, should seek medical advice promptly, and provide travel details to doctor.
     The public may visit these pages for more information: the CHP's JE page, tips for using insect repellents, Facebook Page and YouTube Channel; the DH's Travel Health Service; and the FEHD's Guidebook on Control and Prevention of Mosquito Breeding.

Ends/Tuesday, July 19, 2016
Issued at HKT 21:26