Japanese Encephalitis: Rare Doesn’t Mean Never

Japanese Encephalitis: Rare Doesn’t Mean Never
May 30 18:37 2018 Print This Article

Japanese encephalitis (JE) is a rare, but very serious and potentially fatal, disease of the brain caused by a virus transmitted to humans through bites by infected mosquitoes(1). The virus occurs throughout most of Asia and in some western Pacific regions, parts of Papua New Guinea and the Torres Strait Islands.

JE isn’t usually on the radar for anyone heading to Asian countries and it doesn’t often get a mention in the health FAQs of holiday brochures. This is probably because it is rare, however, just because it is rare, that doesn’t mean it never happens.

In June 2017 there was news of a very tragic death due to Japanese Encephalitis reported in Australia, after an unvaccinated 60-year-old Victorian man visited Phuket, Thailand, on holidays. He had reported receiving some mosquito bites and the mosquito that carries Japanese Encephalitis (mainly Culex species) normally occurs in rural areas, but not always.

The mosquito usually feeds on wading birds and pigs in areas near rice paddies – humans are accidental hosts and for the most part, they don’t pass the virus on to others. When the infected mosquito feeds on a person – at dusk/nighttime – it passes on the Japanese Encephalitis virus which travels through the bloodstream to the brain and attacks the cells. The death of the Victorian man is understood to be the 10th case recorded in Australia since 2001 and one of only a few deaths in that time.

What are the Symptoms of Japanese Encephalitis?

Up to 99 percent of people infected by the rare Japanese Encephalitis virus show no symptoms(1). Some people who have the disease will have a fever and headache, however, those with a more serious infection can present with symptoms such as a stiff neck, (in children mainly there are convulsions), tremors, disorientation, progressing to paralysis and coma. Japanese Encephalitis can cause permanent brain damage or lead to death. If symptoms do occur they will usually develop from five to 10 days after the infecting mosquito bite.

What Can Doctors Do About Japanese Encephalitis?

All medical science can offer anyone infected by the Japanese Encephalitis virus is supportive care, with the hope that the patient’s body and brain can recover by itself. Once a person has the disease their chances of complete recovery are not good. So besides warning that it’s vital to avoid mosquito bites in the first place, what medical science can offer is a vaccine to help prevent the disease from developing in a person bitten by an infected mosquito. There are two different formulations of Japanese Encephalitis vaccine in Australia and your travel health doctor will advise you which is best for you. Anyone planning to travel to any Asian country is strongly advised to at least talk to a travel doctor about how to avoid contracting this terrible disease.

Can Japanese Encephalitis be Transmitted by Humans?

Japanese Encephalitis is spread through the bite of an infected mosquito, so there is virtually zero risk of contracting it from another person even though the infected person has the virus in their blood. Humans don’t develop high enough concentrations of virus in their blood for long enough to pass it on to a feeding mosquito. Most travellers are at a low risk of acquiring the rare but often deadly Japanese Encephalitis, but there are some groups who are at an elevated risk of infection: these include those people who have a prolonged (or repeated) stay in an endemic area, during the wet season and with extensive outdoor activity (and inadequate insect bite avoidance measures).

Important Points:

  • Japanese encephalitis can cause a disease of the brain that results in death in 20 to 30 percent of cases.
  • There is virtually no risk of transmission from a person infected with Japanese Encephalitis to other people.
  • Japanese Encephalitis can be prevented through vaccination.

How Can Travellers Protect Themselves?

Even if a person has been vaccinated against Japanese Encephalitis they should still protect themselves against mosquito bites to lower the risk of it and other diseases that are also transmitted through mosquito bites.

Here are some important tips for protection against mosquito bites:

  • Cover up with light-coloured, loose-fitting long pants and a long-sleeved shirt while out in the open.
  • Use an effective insect repellent on exposed skin.
  • During the peak hours that the Culex mosquitoes bite (dusk and dawn) be especially careful.
  • Aside from the Japanese Encephalitis-carrying mosquitoes that feed at night, there are others which can transmit diseases such as Zika, dengue and chikungunya that bite during the day.
  • Utilise screen doors and windows and remove sites where mosquitoes could breed, such as any containers with stagnant water, from around the house.
  • Avoid areas where there is a known outbreak, or take precautions (insect net, repellents, vaccine or medications) when visiting locations with a high incidence of mosquito-borne diseases such as JE.
  • When planning a tour of regions with an elevated risk of acquiring even rare mosquito-borne diseases such as JE, get the right information before you leave.
  • Only sleep and stay in air-conditioned rooms that have adequate fly-screens.
  • Use a mosquito net over the bed if you are sleeping, especially if it is open to the outdoors.
  • Mosquito nets are more effective if they’re treated with an insecticide, such as permethrin.
  • You can buy pre-treated mosquito nets before travelling, or nets can be treated afterwards, to help in the protection against Japanese Encephalitis and other diseases such as malaria.

For more information about travelling, vaccinations and other advice call Travelvax on 1300 360 164 or visit the website.



  1. http://www.health.nsw.gov.au/Infectious/factsheets/Pages/japanese_encephalitis.aspx
  2. https://www.travelvax.com.au/holiday-traveller/vaccination-requirements
  3. https://www.travelvax.com.au/storenew/anti-insect/mosquito-nets.html


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Jack Allardice
Jack Allardice

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