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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)
- The Indian
Subcontinent including India, Bangladesh, Nepal, Sri Lanka and Pakistan.
- South East Asia
including Myamar, Thailand, Cambodia, Laos, Vietnam, Malaysia,
Indonesia 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 Durussalam. (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 Permetherin* 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 (no studies in those <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.
More information on
Japanese Encephalitis is available during your pre-travel consultation
with Travelvax. Call 1300 360 164 for the location of the clinic nearest
to you.
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