Go to main content
CHP investigates imported case of Japanese encephalitis
     The Centre for Health Protection (CHP) of the Department of Health (DH) is today (August 24) investigating an imported case of Japanese encephalitis (JE) affecting a man aged 61 and urged the public to take precautions against mosquito-transmitted diseases.
     The patient, with good past health, travelled to Yingcheng, Hubei from July 30 to August 13. He developed fever, headache, arthralgia and vomiting since August 13, and consulted a private doctor on August 14. As his symptoms persisted, he attended the Accident and Emergency Department of Princess Margaret Hospital on August 16. He was admitted on the same day for further management and was found to be confused and disorientated upon admission. He has all along been in a stable condition.
     His cerebrospinal fluid tested positive for immunoglobulin M (IgM) antibodies against JE upon testing by the CHP's Public Health Laboratory Services Branch.
     Epidemiological investigations are ongoing. According to the patient's information, his travel collaterals have remained asymptomatic so far. He could recall mosquito bites in the Mainland during the incubation period.
     To date, two JE cases (one under investigation and one imported) have been 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 from 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 a doctor at least six weeks before the trip, and have extra preventive measures to avoid mosquito bites;
  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. If feeling unwell, such as with fever, travellers should seek medical advice promptly, and provide travel details to a doctor.
     The public may visit these pages for more information: the CHP's JE pagetips for using insect repellents, Facebook Page and YouTube Channel; the DH's Travel Health Service; and the Food and Environmental Hygiene Department's Guidebook on Control and Prevention of Mosquito Breeding.
Ends/Wednesday, August 24, 2016
Issued at HKT 18:28
Today's Press Releases