CHP investigates local case of Japanese encephalitis

     The Centre for Health Protection (CHP) of the Department of Health is investigating this evening (October 6) a local case of Japanese encephalitis (JE) and again urged the public to avoid going to rural areas from dusk till dawn when the vector, which breeds in large water bodies such as rice paddies, is most active.
     According to the attending physician and the patient's family, the male patient, aged 59 with good past health, lives in Healthy Village, North Point. He has developed confusion and abnormal behaviour since September 11. He attended Pamela Youde Nethersole Eastern Hospital on September 18 and was found to have fever, left sided weakness and confusion and was admitted for management. He is now in stable condition.
     His cerebrospinal fluid tested positive for immunoglobulin M (IgM) antibodies against JE upon laboratory testing.
     Initial enquiries revealed that the patient had no travel history in the incubation period. His local movements before onset were mainly from his residence to Tsuen Wan to the Hong Kong Boundary Crossing Facilities (HKBCF) of Hong Kong-Zhuhai-Macao Bridge (HZMB) for work. His home contacts have remained asymptomatic and have been put under medical surveillance.
     "As the patient is suffering from confusion and unable to provide further details of his exposure history, epidemiological investigations are ongoing," a spokesman for the CHP said.
     "We are working with the Food and Environmental Hygiene Department (FEHD) to prevent any possible spread of infection. The FEHD and the Agriculture, Fisheries and Conservation Department have been informed for vector investigations, surveillance and control," the spokesman said.
     Officers of the CHP will conduct site visit and field investigations by questionnaire surveys at the patient's residence for active case finding and arranging blood tests. A health talk will be held jointly with the FEHD to deliver health advice to residents and the public.
     Persons who have been to the vicinity of Healthy Village, North Point or HKBCF of HZMB with JE symptoms should call the CHP's hotline (2125 1122) operating from 9am to 5.45pm over the weekend for laboratory investigation or referral as appropriate.
     The CHP has informed the Guangdong and Macau health authorities of the case and will issue letters to local doctors and hospitals to alert them to the latest situation.
     This is the fifth JE case recorded in 2017 and all were locally acquired, four of which were mosquito-borne and one was blood-borne. Two (imported) and two (one local, one unclassified) cases were recorded in 2016 and 2015 respectively.
     JE is a mosquito-borne disease and the JE virus is transmitted by the bite of infected mosquitoes. The principal vector is called Culex tritaeniorhynchus. JE mainly occurs in rural and agricultural areas of Asia and the Western Pacific. The infected mosquito transmits the 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 the JE virus. Symptoms usually start around four to 14 days after being infected.
     To prevent JE, the public should take general measures to prevent mosquito bites and avoid going to rural areas from dusk till dawn when the mosquitoes are most active. Travellers to endemic areas should take special note.
     The public should:
     1. Wear loose, light-coloured, long-sleeved tops and trousers, and use DEET-containing insect repellent on exposed parts of the body and clothing;
     2. Take additional preventive measures in outdoor activities:
  • Avoid using fragrant cosmetics or skin care products;
  • Re-apply insect repellents according to instructions;
     3. Special notes during travel:
  • If going to affected areas, arrange consultation with a doctor at least six weeks before travel, and have extra preventive measures to avoid mosquito bites;
  • Vaccination is recommended for travellers who plan to stay one month or longer in endemic areas, particularly in rural areas, and for short-term (less than one month) travellers if they plan to have significant extensive outdoor or night-time exposure in rural areas during the transmission season of the disease;
  • During travel in endemic rural areas, carry a portable bed net and apply permethrin (an insecticide) on it. Permethrin should not be applied to the skin. Seek medical attention promptly if feeling unwell; and
  • Travellers feeling unwell, such as having fever, should seek medical advice promptly, and provide travel details to the doctor.
     The public may visit the CHP's JE page, tips for using insect repellents, Facebook Page, YouTube Channel and Travel Health Service and the FEHD's Guidebook on Control and Prevention of Mosquito Breeding for more information.

Ends/Friday, October 6, 2017
Issued at HKT 22:01