Reemergence, Persistence, and Surveillance of Vivax Malaria and its Vectors in the Republic of Korea

Abstract:
Plasmodium vivax reemerged in 1993 after a hiatus of 14 years and increased exponentially among South Korean military and civilian populations through 1998. With increased use of chemoprophylaxis by the South Korean military, malaria stabilized and then sharply decreased through 2004. Malaria cases sharply increased in 2005 through 2007 to 2001 levels even though the Korean military chemoprophylaxis program was expanded to approximately 200,000 soldiers. Malaria among US service members demonstrated similar trends and the sites of infections were identified as training areas near the heavily fortified demilitarized zone (DMZ). Similarly, Korean data show that nearly all malaria transmission occurred in the northernmost two provinces bordering the DMZ. In 2005, it was reported that members of the Anopheles sinensis Group could not be identified using morphological techniques. Extensive larval and adult surveillance showed that An. kleini and An. pullus population densities were highest in malaria high-risk areas, while malaria transmission was extremely low where An. sinensis predominated. These and other data identify An. kleini and An. pullus as the primary vectors of malaria in Korea. The number of vivax malaria cases in the US military doesn’t warrant the widespread use of chemoprophylaxis, but instead, warrants an increased emphasis on preventive medicine measures (including permethrin impregnated uniforms and approved repellents). This is especially important since the Korean military experienced a large number of chemoprophylaxis breakthroughs during 2007, indicating a potential for drug resistance.