What is Japanese encephalitis virus?
Japanese encephalitis virus is a mosquito-borne illness which survives in a cycle of infection most commonly involving pigs and wading birds. While it remains rare in mainland Australia, it is prevalent in rural areas of Asia and the Western Pacific.
FAQs
Which countries have Japanese encephalitis virus?
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Japanese encephalitis virus is found in eastern, southeast and southern Asia. It is endemic in Papua New Guinea and the Torres Strait. Recently, very occasional infections have been seen in mainland Australia.
For which travellers is Japanese encephalitis virus immunisation recommended?
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Those who will be spending more than one month in areas with Japanese encephalitis virus during the transmission season should discuss vaccination with their doctor.
What are the side effects of Japanese encephalitis virus vaccination?
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With the single dose vaccine, the most common adverse effects in adults are pain at the injection site, headache, and fatigue. Most symptoms resolve in less than three days.
How much does the Japanese encephalitis vaccine cost?
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This depends on the provider, but the immunisation can often be obtained for under $300.
What to Know
Japanese encephalitis virus symptoms
Most people who contract Japanese encephalitis virus have a very mild infection and many don't experience any symptoms at all.
For those who do have symptoms, these occurs five to fifteen days after the bite of the infected mosquito. Problems include fever, fatigue and headache. Nausea and diarrhoea can also be features. In less than one percent of people, an infection of the brain called encephalitis develops. This can cause progressive drowsiness, confusion and coma. Around 20 to 30 percent of those admitted to hospital with this form of the illness do not survive and those who do recover have high rates of long-term neurological disability.
Japanese encephalitis virus diagnosis and treatment
Diagnosis of Japanese encephalitis virus infection is most commonly made by detecting specific antibodies in the blood or spinal fluid. The virus itself can also occasionally be detected in these body fluids using PCR testing, but more commonly it is undetectable by the time someone reaches their doctor.
There are no specific anti-viral therapies with demonstrated efficacy against Japanese encephalitis virus. Treatment involves supportive care, which can involve mechanical respiration and other life support measures for people in a coma.
Japanese encephalitis virus prevention
Prevention of Japanese encephalitis virus involves mosquito avoidance in countries where transmission occurs. For those spending more than one month in areas with Japanese encephalitis virus during the transmission season or those travelling frequently to these places, vaccination is an additional preventive measure which can be used.