| Healthy Travel |
Japanese Encephalitis
The Disease
Japanese encephalitis is a mosquito-borne viral disease that occurs in rural areas of Asia, although occasional cases have been reported in urban areas. The disease begins clinically as a flu-like illness with headache, fever and gastrointestinal symptoms. Confusion and disturbances in behaviour may occur at this early stage. The illness may progress to a serious infection of the brain and may be fatal in one in three cases. Another one third of cases survive with serious neurological effects, such as paralysis, and the remaining third will recover without further problems.
Where is it found?
The disease chiefly occurs in three main areas:
China and Korea (June through September)
Indian Subcontinent including India, Bangladesh, Nepal, Sri Lanka and Pakistan.
South East Asia including Myanmar, Thailand, Cambodia, Laos, Vietnam, Malaysia, Indonesia (NB. Bali: year round) and the Philippines. (Wet and early dry season).
Japanese Encephalitis also occurs with lower frequency in Japan, Taiwan, Singapore, Hong Kong, Eastern Russia, Guam, Saipan and Brunei Darussalam. (Wet and early dry season)
The disease is seasonal. In China and Korea and other temperate climates, the transmission season extends through the summer and autumn. In subtropical and tropical regions risk is associated with the rainy season, which varies in each country. However, sporadic cases may occur at any time of the year.
Areas above 1500 metres and urban areas are generally low-risk areas.
Risk to travellers
Travelvax believes that the risk to short-term and persons who confine their travel to urban centres is very low. Expatriates and travellers living for prolonged periods (>30 days) in rural, particularly agricultural, areas where Japanese Encephalitis is endemic or epidemic are at greater risks. Travellers with extensive unprotected outdoor exposure in rural areas, particularly during the evening and at night - especially those engaging in activities such as bicycling, camping or engaged in certain occupational activities in rural area - may be at high risk, even if their trip is brief. Insect prevention measures are paramount.
Travellers are advised to stay in screened or air-conditioned rooms, or to use bed nets impregnated with Permethrin* or Deltamethrin* when such accommodation is unavailable. Bite avoidance measures such as the use of insecticide, repellents and protective clothing to avoid mosquito bites are also important.
Vaccination
Type:
- Inactivated virus vaccine*.
Standard Schedule:
- 2 Doses given IMI on days 0, 28 + 4 days
- Dose is for those aged >18 yrs of age (studies now underway for <18yrs)
- Boosters: probable protection for 1-2 years (studies still being carried out).
Level of protection:
- 96% after 2 doses (28 days apart)
Contraindications: Should not be administered to individuals who have previously experienced a serious reaction to this vaccine or who are known to be hypersensitive to any of the vaccine components. Individuals who show hypersensitivity reactions after receiving the first dose should not be given the second dose.
Should not be used in those < 18 years.
Possible side effects:
Approx 40% of subjects experience adverse reactions, they usually occur in the first 3 days following vaccination. Side effects are usually mild and only in the first few days.
Most commonly reported were:
- 26% headaches
- 21% aches and pains
- 13% flu like illness
- 13% fatigue
* Available from Travelvax clinics.