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Japanese encephalitis
Infection
Mosquitoes transmit the infection. The virus is found naturally in pigs and the mosquitoes often breeds in rice fields, which makes JE an infection seen especially in rural areas.
Vaccination
The vaccine contains inactivated virus. 80% are protected after 2 vaccinations and more than 95% after three.
The initial series consist of 3 vaccinations with 2 weeks in between, which give protection for up to 2 years. A booster vaccination after 2 years prolongs the protection by 3 years.
JE-vaccination is part of the childhood vaccination programme in China, Japan, Taiwan, Thailand and South Korea.
Symptoms
Most infections pass unnoticed. The initial symptoms are headache, reduced consciousness and fever. The infection may be lethal and may cause permanent brain damage.
Diagnosis
Detection of antibodies in a blood sample.
Treatment
Supportive only. No specific antiviral drugs available.
Prevention
Avoid mosquito bites. The mosquitoes, which transmit JE bite primarily during daytime.
More about
There has been some debate about side effects from JE vaccine. The most common adverse reaction is an allergic rash, which sometime is general and accompanied by fever. The frequency is between 1 per 1,000 and 1 per 10,000 vaccinated persons.
The risk of acquiring symptomatic JE during travel is estimated to about 1 per million travellers. vaccination is therefore not recom-mended to short-term visitors.
The WHO estimates that there are at least 50,000 cases per year in Asia and 10,000 deaths. It is difficult to know the risk for the traveller because the virus is naturally found in pigs and the population has been vaccinated.
Edited 31. August 2007
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