Border malaria in the republic of Korea: trends and health implications for US military and civilian populations

Plasmodium vivax was endemic on the Korean Peninsula for many centuries until the late 1970’s. Malaria re-emerged among ROK military populations along the demilitarized zone (DMZ) in 1993 and rapidly spread to nearby civilian communities. By 2000, the total number of reported cases increased to 4,142. From 2000 through 2004, the number of malaria cases rapidly declined to 826, most likely as a result of increased awareness, vigilance, and an expanded ROK military chemoprophylaxis program that included 160,000 soldiers. While it was presumed that malaria would rapidly expand throughout Korea, nearly all transmission remained near the DMZ. As new information was discovered, including two previously unrecognized species (An. kleini and An. belenrae), geospatial distributions (high populations of An. kleini populations near the DMZ with low populations south of Seoul), and vector potential, the identification of malaria health threat risks became more apparent. With the integration of air-conditioned barracks from ill-kept tents, malaria cases decreased dramatically. In addition to preliminary evidence, which demonstrates that civilian communities serve as reservoirs for vivax malaria and infections among ROK military, high infection rates among mosquitoes were observed in mosquitoes collected in the DMZ. These data indicate that the malaria situation is much worse in North Korea than in South Korea. Mosquito-borne disease surveillance is required to better understand the dynamics of the epidemiology of malaria in Korea to identify present and future health risks.