Japanese Encephalitis

What is Japanese encephalitis?

Japanese encephalitis is a viral infection spread through the bite of infected mosquitoes. Most infections cause no symptoms or only a mild illness, but in some cases the virus can affect the brain, leading to serious complications.

Where is Japanese encephalitis found?

Japanese encephalitis occurs in parts of:

• East Asia
• Southeast Asia
• South Asia
• The Western Pacific region

How is Japanese encephalitis spread?

Japanese encephalitis is spread through the bite of infected mosquitoes, primarily those that breed in rice fields and standing water. The mosquitoes:

• Usually bite between dusk and dawn.
• Become infected after feeding on infected birds or pigs.
• Do not spread the virus directly from person to person.

Symptoms

Symptoms usually develop 5 to 15 days after being bitten by an infected mosquito. They may include:

• Fever
• Headache
• Vomiting
• Confusion
• Neck stiffness
• Seizures
• Weakness
• Difficulty moving

In severe cases, the infection can cause inflammation of the brain (encephalitis), which requires urgent medical attention.

Prevention

The risk of Japanese encephalitis can be reduced by:

• Using insect repellent containing DEET.
• Wearing long-sleeved clothing and long trousers, particularly during the evening and night.
• Sleeping under mosquito nets where appropriate.
• Staying in accommodation with screened windows or air conditioning where possible.
• Avoiding mosquito bites, especially in rural and agricultural areas.

Japanese encephalitis vaccine

A vaccine is available in the UK to help protect against Japanese encephalitis. It may be recommended for travellers visiting countries where the disease is present, particularly those spending extended periods in rural areas or taking part in outdoor activities.

How is the vaccine given?

• The vaccine is given as an injection into the upper arm.
• The primary course consists of 2 doses, with the second dose given 28 days after the first.
• For some adults, an accelerated schedule may be available if there is limited time before travel.

During your travel consultation, our pharmacist will advise you on the most appropriate vaccination schedule based on your travel plans.

Who can receive the vaccine?

The Japanese encephalitis vaccine can be given to adults and children aged 2 months and over. During your travel health consultation, our pharmacist will assess your destination, itinerary, length of stay, and planned activities to determine whether the vaccine is appropriate for you.

Who should consider vaccination?

Vaccination may be appropriate for travellers who:

• Are travelling to countries where Japanese encephalitis is present.
• Will be spending a month or longer in endemic areas during the transmission season.
• Are staying in rural or agricultural areas.
• Plan to camp, hike, cycle, or spend significant time outdoors.
• May have increased exposure to mosquitoes due to their travel plans.

A travel health consultation can help determine whether the Japanese encephalitis vaccine is appropriate for your trip.