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Risk for Japanese encephalitis may be higher than believed
Many travelers who do not meet the criteria for recommended vaccination may be at risk for Japanese Encephalitis.
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NEW ORLEANS – All travelers to Asia may be at some risk for Japanese encephalitis and should be made aware of this risk, according to researchers who conducted a recent study of the disease.
The researchers, led by Elaine C. Jong, MD, professor of medicine at the University of Washington, Seattle, presented their findings at the American Society of Tropical Medicine and Hygiene’s 57th Annual Meeting, held here in December. Jong and her colleagues said that although guidelines for Japanese encephalitis vaccination exist, many travelers who do not meet the guidelines’ criteria for vaccination may still be at risk for the disease.
Meta-analysis
The researchers conducted a meta-analysis by completing a literature review to find cases of Japanese encephalitis among Western travelers between 1989 and 2008. Eighteen cases of Japanese encephalitis in Western travelers were found.
Clinical outcomes for all 18 patients were reported. Four) of the 18 patients fully recovered; three died and 11 still had residual sequalae at the end of the case report.
A further assessment of these case reports indicated that, according to current ACIP recommendations for Japanese encephalitis vaccination, half of these patients should not have received vaccination.
Vaccine recommendations
Although Japanese encephalitis is associated with 10,000 to 15,000 worldwide deaths per year, it is typically rare among travelers.
The recommendations for Japanese encephalitis vaccination, established in 1993 by the ACIP, were designed to offer immunization to travelers at high-risk for Japanese encephalitis, while limiting potential adverse effects of vaccination among those deemed to be at a lower risk. “The ACIP recommendations were designed to restrict exposure to a potentially reactogenic vaccine while acknowledging that Japanese encephalitis is very rare in travelers,” Jong and her colleagues wrote. “However, this review finds that Western travelers may have acquired Japanese encephalitis during journeys that did not fulfill the criteria for Japanese encephalitis vaccination.”
The researchers also noted that although the Japanese encephalitis vaccination guidelines have not been updated since 1993, new vaccines with better safety profiles are now available. “The focus of travel counseling on Japanese encephalitis risks and prevention can now be directed at the risks of acquiring the disease and its consequences, instead of the risks of vaccination,” the researchers wrote. – by Jay Lewis
For more information:
- Jong E, Tsai T. Reassessing the risk of Japanese Encephalitis in travelers: Lessons from case reports. Abstract #2945. Presented at: The American Society of Tropical Medicine and Hygiene’s 57th Annual Meeting; Dec. 7-11, 2008; New Orleans.