Japanese Encephalitis
For rural Asia in the transmission season — rice fields, pig farms, and longer or outdoor stays.
Japanese encephalitis is a viral infection of the brain spread by mosquitoes that bite between dusk and dawn. Most infections cause no symptoms, but around one in two hundred and fifty becomes serious, and of those a third are fatal and many more leave lasting damage. There is no treatment. Despite the name it is found across twenty-four countries in Asia and the western Pacific, from Pakistan to Japan and south to northern Australia.
Who is at risk
The virus lives in pigs and wading birds, so the risk is in the countryside: rice paddies, pig farms and villages, mainly in the rainy season. A short city break carries very little risk. It rises with time in rural areas, outdoor activities such as camping, cycling and fieldwork, and stays of a month or more. Even a short rural trip in the wrong season can be enough.
The vaccine
Ixiaro is given as two injections twenty-eight days apart, and is suitable from two months of age. Adults who are leaving sooner can have the second dose at seven days instead. If you remain at risk, a booster twelve to twenty-four months after the course keeps protection going, with a second booster ten years later.
Bite avoidance still matters
Cover up at dusk, use a repellent containing DEET, and sleep under a treated net or in a screened room. The same measures protect you against malaria and dengue.
Not sure whether you need this one? Book the travel consultation instead and the pharmacist will go through your trip with you.