CHP investigates imported case of Japanese encephalitis
The Centre for Health Protection (CHP) of the Department of Health is investigating today (August 20) an imported case of Japanese encephalitis (JE) and urged the public to take proper mosquito control and personal protective measures when travelling to JE endemic areas.
The case involves a 49-year-old female living in Shatin District. Initial investigations revealed that she travelled to the Philippines between July 21 and August 4, and visited rural areas there. She returned to Hong Kong on August 4 and developed fever, headache and vomiting since August 10. She attended the Accident and Emergency Department of Prince of Wales Hospital on August 12 but did not require hospitalisation. As her symptoms persisted, she attended the hospital again on August 14 and was admitted to the hospital. She is currently in stable condition.
Her cerebrospinal fluid sample tested positive for immunoglobulin M (IgM) antibodies against JE upon laboratory testing. Since the patient stayed in the Philippines during the incubation period, the CHP considered that she was infected during travel, and the case was classified as an imported one. Her four household contacts are currently asymptomatic and under medical surveillance. The CHP's epidemiological investigations is ongoing and the case will be reported to the health authority of the Philippines.
This is the first JE case recorded in Hong Kong this year, which is an imported case. In the past five years (from 2020 to 2024), no JE cases were recorded in Hong Kong.
JE is mainly transmitted by mosquito and the principal vector is Culex tritaeniorhynchus. It is not transmitted from person to person. Mosquitoes breed in areas where there is a lot of stagnant water, such as rice paddies, and become infected when they bite pigs or wild birds infected with the JE virus. The infected mosquitoes then transmit the virus to humans and animals during biting. JE is prevalent in rural areas of Asia and the Western Pacific Region, especially in hot season. In the subtropics and tropics, transmission can occur year-round, often with a peak during the rainy season.
Symptoms usually start around four to 14 days after being infected. Most patients with JE have mild symptoms, with no significant symptoms other than fever and headache. However, approximately one in every 250 infections is associated with severe illnesses characterised by rapid onset of high fever, headache, neck stiffness, disorientation, coma, seizures, spastic paralysis, and even death.
To prevent JE, the public should take general measures to prevent mosquito bites. Members of the public, especially those planning to travel to JE endemic areas, should take the following measures:
• Consult a doctor at least six weeks before travelling to JE endemic areas, and have extra preventive measures to avoid mosquito bites;
• Travellers planning to stay in JE endemic areas, particularly in rural areas, for one month or longer, or those planning to have significant extensive outdoor or night-time exposure in rural areas during the transmission season of the disease, may consult their family doctor and consider receiving JE vaccination;
• During travel in JE endemic rural areas, bring a portable bed net and apply permethrin (an insecticide) on it. Permethrin should not be applied directly to the skin. Seek medical attention promptly if feeling unwell; and
• Travellers feeling unwell, such as having a fever, should seek medical advice promptly, and provide travel details to the doctor.
The public may visit the CHP'sJE page,tips for using insect repellents, and the CHPFacebook Page,Instagram AccountandYouTube Channel, Travel Health Serviceand also theMosquito Prevention and Control dedicated pageof the Food and Environmental Hygiene Department for more information.
Source: AI-found images
