Japanese Encephalitis Vaccine

Japanese encephalitis (JE) is a serious viral infection that can cause swelling of the brain. It is spread through the bite of infected mosquitoes. The disease is found across most of Asia and parts of the western Pacific, according to the CDC.

Most people infected with Japanese encephalitis have no symptoms. In the small number of cases where illness does develop, it can be severe. Per the CDC, roughly 20–30% of people who develop brain inflammation from the virus do not survive, and up to half of survivors may have lasting neurological effects.

There is no cure for Japanese encephalitis. Vaccination and avoiding mosquito bites are the best ways to protect yourself before travel.

Japanese encephalitis spreads to humans through the bite of an infected mosquito. According to the CDC, the virus mainly spreads between animals and insects, with mosquitoes then infecting humans. Person-to-person spread has not been documented.

The risk is highest in rural and agricultural areas. Risk is especially high near rice or pig farms close to human populations. In temperate parts of Asia, transmission peaks in summer and fall. In tropical and subtropical regions, it can occur year-round.

There is only one FDA-approved Japanese encephalitis vaccine available in the US. According to the CDC, this vaccine is approved for use in people aged 2 months and older.

The vaccine is given as a two-dose series. For most adults, the two doses are given 28 days apart, though adults 18 to 65 may receive the doses as few as 7 days apart when needed. Children aged 2 months through 17 years receive the doses 28 days apart. The full series should be completed at least one week before travel.

The most common side effects are soreness at the injection site, headache, and muscle aches. Serious reactions are rare, according to the CDC.

The Japanese encephalitis vaccine is given as a two-dose series, with the second dose serving as part of your initial protection. For most adults, the two doses are given 28 days apart. Adults 18 to 65 may receive them as few as 7 days apart when needed.

A separate booster dose may be recommended if you continue to visit areas where Japanese encephalitis is present. Per the CDC, this booster should be given at least one year later if visiting affected areas. Research has shown that 96% of people who received a booster dose were still protected approximately six years later.

If you are unsure whether a booster is right for you, speak with a travel health specialist before your trip.

Per the CDC, vaccination is recommended for some types of travelers and individuals:

• Travelers to regions with active transmission
• Travelers to rural areas where infection could occur
• Travelers staying longer than one month
• Travelers engaging in certain activities that pose more risk

To learn if the vaccine is right for your trip, speak with a travel health specialist by calling or book an appointment online today!

Risk areas of Japanese encephalitis are present through most of East Asia. Countries with known risk include:

Source: CDC

• Myanmar (Burma) – Widespread, year-round cases; risks are highest in delta and lowland areas
• China – Peak season from June to October, present in all provinces except Qinghai
• India – Present in large parts of country, peak season generally May to November but can vary by region
• Indonesia – Widespread, year-round cases but seasonality can vary by island
• Japan – Rare sporadic cases, most common June to October
• Laos – Widespread, year-round cases; peak season is June to September
• Malaysia – Widespread year-round cases; higher rates reported in Sarawak
• South Korea – Widespread cases, most common May to November
• Vietnam – Widespread, year-round; peak season May to October

Any region of the Western Pacific with temperate climate and the presence of mosquitoes have the virus. This section’s map provides an idea of the highest risk areas.

Vaccination is required for some military and government personnel traveling to these regions. Be sure to check any requirements before your trip.

According to the WHO, the majority of JE cases show no symptoms. It can take five to 15 days for symptoms to develop. Travelers may have returned home or is in the middle of a trip when it becomes serious.

Symptoms often start mild with fever, headache or vomiting. Over the next few days, there can be mental or neurological changes. Weakness and movement problems occur. Seizures are common, especially among children.

Per the CDC, about 20 to 30 percent of those infected with Japanese encephalitis die. Between 30 and 50 percent of survivors have serious mental, neurological or cognitive problems. Paralysis similar to polio can also occur.

There is no treatment for Japanese encephalitis, only supportive care. This means an infected person can be made comfortable, but may not always recover.

Vaccination is the best way to prevent Japanese encephalitis. The CDC recommends the Japanese encephalitis vaccine for travelers spending one month or more in risk areas. It is also recommended for frequent travelers and those relocating to regions with the virus.

In addition to vaccination, the CDC recommends taking steps to avoid mosquito bites, including:

• Using insect repellents containing DEET, picaridin, or other EPA-registered ingredients
• Wearing long sleeves and pants, especially during evening and nighttime hours when mosquitoes are most active
• Sleeping in air-conditioned or screened rooms, or under an insecticide-treated bed net
• Treating clothing and gear with permethrin for added protection

There is no specific treatment for Japanese encephalitis. According to the CDC, doctors can only treat the symptoms, there is no medication that targets the virus itself. This makes prevention through vaccination and avoiding mosquito bites the most important option for travelers.

If you develop symptoms of a serious neurological illness during or after travel to an area where Japanese encephalitis is present, seek medical attention immediately and tell your doctor where you traveled.

Passport Health clinics throughout the country carry JE vaccine. Schedule your vaccination today by calling or book online now.