Lymphatic filariasis in soldiers exposed in INDOPACOM

Some military organizations in the U.S. Indo-Pacific Command (INDOPACOM) give returning soldiers presumptive treatment for filariasis. As there have been few clinical cases in recent decades, the historical basis for this chemotherapy was reviewed. During the Second World War, U.S. Marines stationed on Polynesian islands such as Tonga, Samoa, and Fiji experienced clinical lymphatic filariasis. Although thousands of both U.S. and Australian soldiers served in New Guinea, few, if any, cases of lymphatic filariasis were ascribed to Melanesia. While the French Army reported dozens of cases of filariasis among its service members during the 1950s Vietnam conflict, the U.S. military experienced only a few cases among the nearly 2 million service members who served in Vietnam in the 1960s. Australian soldiers deployed to Timor Leste in the 21st century showed rare seroconversions to filaria but no clinical disease. Following mass drug administration to eliminate lymphatic filaria in the INDOPACOM region, exposure in deployed soldiers rarely occurs and preventive chemotherapy should cease.