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Dangers of Japanese Encephalitis Underestimated by Travellers

Vaccination against the potentially fatal, mosquito-borne Japanese encephalitis should be considered for all at-risk travellers, and the definition of 'at-risk' should be expanded, according to an article and two letters published in the current issue of The Medical Journal of Australia.

Associate Professor James McCarthy of the Queensland Institute of Medical Research and Dr Catherine Geraghty of the Royal Brisbane Hospital report the case of a 32-year-old traveller with Japanese encephalitis. She presented to hospital immediately on disembarking from a flight from Bangkok after a 2-month trip across south-east Asia.

"She had a 5-day history of gastrointestinal symptoms, fever and altered mental state, including mood elevation, hallucinations, and lethargy," Associate Professor McCarthy said.

"She complained of persistent headache, mild photophobia and neck discomfort. Her partner commented on her slow mentation, reduced concentration and personality change.

"Global impairment of cognitive function and tremor persisted after she was discharged from hospital. She was able to return to work only after a 5-month convalescence," he said.

Japanese encephalitis, which is spread by mosquitoes, is the leading cause of viral encephalitis in Asia, with recent epidemics in India, Malaysia and Nepal.

Most infections cause no symptoms. But for those who experience symptoms, 25-30 per cent of cases will be fatal. Of the survivors, 30-50 per cent will suffer long-term neuropsychiatric effects.

Associate Professor McCarthy said this case is a warning that all at-risk Australian travellers should consider vaccination against Japanese encephalitis, despite its high cost ($300 for three doses administered over 30 days) and occasional reports of delayed and (rarely) life threatening adverse reactions.

The vaccine is recommended for travellers spending a month or more in rural Asia and parts of Papua New Guinea and for those spending a year or longer anywhere in Asia (except Singapore).

All permanent residents of the outer Torres Strait Islands and non-residents spending more than 30 days there during the wet season should also be vaccinated.

Residents of northern Cape York and the Torres Strait Islands receive free vaccinations under the Queensland Government Vaccination Programme, while members of the Australian Defence Force who may be at risk are also immunised.

Dr Joshua Hanson, Training Physician at the Cairns Base Hospital, and colleagues, detail another case of Japanese encephalitis in a 66-year-old man who lived on a farm near Port Moresby in PNG.

This patient required three weeks of intensive care and, five months later, could walk only with assistance and required a tracheostomy tube.

This case highlights the need to reconsider the current recommendation to vaccinate Australians only if they intend travelling to the Western Province of Papua New Guinea.

Professor George Rubin of the University of Sydney reports that ATAGI (Australian Technical Advisory Group on Immunisation) agrees that Hanson's findings are compelling and sufficient to warrant expanding the current recommendation for Japanese encephalitis vaccination.

ATAGI is proposing the recommendation be changed to include travellers staying more than one month in all parts of Papua New Guinea, not just those planning to stay in the Western Province.

A public consultation process is being conducted about this change. A consultation paper is available from the Immunise Australia Program website (www.immunise.health.gov.au). Submissions close on 17 September.

The Medical Journal of Australia is a publication of the Australian Medical Association.

CONTACT     Assoc Prof James McCARTHY                       0414424659 / 07 36368111 RBH then page

                        Dr Joshua HANSON                                       0413 935 134 / 07 4050 6469

                        Judith   TOKLEY, AMA Public Affairs            0408 824 306 / 02 6 270 5471

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