Prevention of malaria for persons who travel for more than 6 months is complex and should be individualized, with advice from travel medicine specialists, according to a review article in the November 8 issue of JAMA.
There were more than 800 million trips by travelers worldwide in 2005, according to background information in the article. For long-term travelers visiting malaria-endemic countries, recommendations for prevention have been difficult to standardize due to the diversity of long-term travelers and their itineraries, the variation in the quality of and access to medical care, the limited data on malaria incidence in travelers overseas, and the lack of controlled studies on long-term safety and effectiveness of antimalarial agents. Further complicating the recommendations is the growth in the intensity of transmission and resistance patterns of the malaria parasites, the seasonality of transmission, and the wide range of international guidelines and travelers' beliefs and expectations.
Lin H. Chen, M.D., of Mount Auburn Hospital, Cambridge, Mass., and colleagues conducted a review of relevant studies and articles, published through July 2006, to examine the risk of malaria in long-term travelers, recent developments in personal protective measures, and the safety and tolerability of malaria treatments during long-term use and to consider prevention strategies.
The studies indicated that long-term travelers (more than 6 months) have a higher risk of malaria than short-term travelers. "Long-term travelers underuse personal protective measures and adhere poorly to continuous chemoprophylaxis regimens. A number of strategies are used during long-term stays: discontinuation of chemoprophylaxis after the initial period, sequential regimens with different medications for chemoprophylaxis, stand-by emergency self-treatment, and seasonal chemoprophylaxis targeting high-incidence periods or locations. All strategies have advantages and drawbacks," the researchers write.
The authors add that vivax malaria (a form of malaria marked by convulsions that occur every 48 hours and caused by the parasite Plasmodium vivax) causes significant illness in travelers, but relapses of vivax malaria are not prevented with the current first-line chemoprophylaxis regimens.
"Long-term travelers to malaria-endemic areas face risk of death, morbidity, and reduced productivity because of malaria. General guidelines are desirable, but recommendations for malaria prevention in long-term travelers must be individualized and should be provided by travel medicine specialists. Personal protective measures are paramount. Identification of reliable medical facilities at destination is crucial for long-term travelers regardless of their malaria prevention strategies, and a number of resources are available to aid in this process. Data on safety of chemoprophylaxis drugs show reasonable clinical support for long-term use, particularly for mefloquine."
"All travelers should be advised to carry or arrange adequate supplies of antimalarial agents, because counterfeit drugs are rampant in developing countries. Long-term travelers should also consider evacuation insurance for medical emergencies," they write. "Presumptive antirelapse therapy should be considered for long-term travelers who have been intensively exposed to P vivax. Because inconsistent recommendations undermine the adherence to any preventive strategy, national and international experts should strive toward consensus on guidelines for malaria prevention in long-term travelers."
(JAMA. 2006;296:2234-2244. Available pre-embargo to the media at www.jamamedia.org.)
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