Dr Yeung Ho Hong 楊浩康 醫生 health-prevention-info

Japanese encephalitis vaccine (日本腦炎疫苗)

Dr Yeung Ho Hong ( 楊浩康 醫生 ) 2021-12-10

Japanese encephalitis vaccine (日本腦炎疫苗)


Japanese encephalitis is caused by the Japanese encephalitis virus. Japanese encephalitis is a disease transmitted by mosquitoes, and Culex tritaeniorhynchus is the main vector. When a mosquito bites a bird or pig with the virus, it becomes infected. When these infected mosquitoes bite humans, they will transmit Japanese encephalitis virus to humans. Japanese encephalitis is mainly prevalent in the suburbs and rural areas of Asia and the Western Pacific. Its incubation period is 4 to 14 days. Most of the infected patients have no obvious symptoms after being infected, and usually only have mild symptoms such as fever or headache. However, if there is a serious infection, the patient will develop severe symptoms within a short period of time. They may have high fever, severe headache, confusion, neck stiffness, coma, convulsions, and paralysis. The case fatality rate of patients with symptoms can be as high as 30%. And even if they recover, 20% to 30% of the survivors will have permanent intellectual, behavioral, or neurological sequelae, such as paralysis and convulsions.

To prevent Japanese encephalitis, having Japanese encephalitis vaccine can be considered. Japanese encephalitis vaccine is safe and effective, and the vaccine is currently available in Hong Kong. If you plan to travel to areas where Japanese encephalitis is endemic, especially the rural areas, and plan to stay in those areas for 1 month or longer, you can consider having Japanese encephalitis vaccine. If the travellers’ plan is for short-term travel (less than a month), but during the transmission season, and the travellers will spend most of the time outdoor or in night-time in the suburbs and rural areas, they should also consider having Japanese encephalitis vaccine.