Malaria antibodies and mefloquine levels among United Nations troops in Angola

Background: The United Nations deployed about 8,000 soldiers in a peacekeep ing mission in Angola. Malaria is the most common disease there and consequ ently it was the major risk to the UN troops. Most of them are from malaria free areas. As a result of improper prophylactic measures there were many cases of malaria, including some deaths in 1995. In February-March 1996, an Israeli team was sent to Angola to evaluate the malaria situation among UN soldiers. This paper deals specifically with some aspects of chemoprophyla xis and diagnosis. The efforts were concentrated in one particular area whe re malaria incidence had been reported as the highest. Methods: Blood samples were collected from nonimmune soldiers who were usin g mefloquine as a prophylactic drug and were exposed to malaria. The mefloq uine and the antimalarial antibody plasma levels were monitored. Results: While the local laboratory indicated that about 80% had a malaria episode, the serological results revealed that only 5 soldiers of the 56 (9 %) examined had antimalarial antibodies, of which 3 were Angolans. Despite a controlled prophylactic regimen there was considerable variability in mef loquine plasma levels: 46% of the samples were below the required prophylac tic level and 26% above it. All patients who were proven positive with mala ria by both microscopic and serologic observation had a low level of mefloq uine. Conclusions: In field conditions, a kit which identifies plasmodial antigen s, is preferable, to a microscopic diagnostic method. Controlled mefloquine prophylaxis may not prevent malaria, especially when blood levels are low. The reason for the low mefloquine blood levels is not clear and needs furt her evaluation.