Japanese Encephalitis

What you need to know about Japanese Encephalitis

Japanese Encephalitis is a rare but serious viral infection which is spread by infected mosquitoes and occurs in most of the Far East and South-East Asia countries. It is usually mild, but in some cases it can cause inflammation (swelling) of the brain (encephalitis), leading to permanent brain damage or death.

Mosquitoes become infected by feeding on domestic pigs and wild birds infected with the Japanese Encephalitis virus. Infected mosquitoes then transmit the Japanese Encephalitis virus to humans and animals during the feeding process although the illness cannot be passed on from person to person.

High-risk areas

High-risk areas for Japanese Encephalitis include tropical northeast Australia and East Asia, including:

• Cambodia
• China
• India
• Indonesia
• Korea
• Laos
• Malaysia
• Myanmar (Burma)
• Nepal
• Philippines
• Singapore
• Sri Lanka
• Thailand
• Vietnam

Despite its name, Japanese Encephalitis is now relatively rare in Japan because of mass immunisation programmes.

Signs and symptoms

Mild infections can sometimes occur without apparent symptoms other than mild fever with headache. More severe infection is marked by quick onset.

• Headache
• High fever
• Neck stiffness
• Disorientation / confusion
• Coma
• Tremors
• Occasional convulsions (especially in infants)
• Paralysis

The vaccine

There is one vaccine for Japanese Encephalitis (Ixiaro) currently licensed in the UK for use in adults and children over two months old.

The vaccination is given as an injection and requires two doses for full protection, with the second dose given 28 days after the first. The second dose should ideally be completed at least a week before travelling.

The Japanese Encephalitis vaccine is not available on the NHS, and each dose will normally cost £80 per person. It’s a good idea to include this when budgeting for your trip.

If you continue to be at risk of infection, a booster dose of the vaccine should be given between 12 and 24 months after you are first vaccinated.