Status ofPlasmodium vivaxMalaria in the Republic of Korea after Reemergence

The annual number of Plasmodiumvivaxmalaria cases had rapidly increased since its reemergence in theRepublic of Korea (ROK) in 1993 to reachmore than 4,000 cases in 2000. Since 2001, it began to decrease to 864 cases in 2004, and once again increased to reachmore than 2,000 cases by 2007. P. vivax malaria mainly has occurred in the areas adjacent to the Demilitarized Zone, which implies that current malaria occurrence in ROK has been strongly influenced by malaria situation of the Democratic People’s Republic of Korea (DPRK). Besides the direct influence from DPRK, local transmission within ROK also likely occurred. Chemoprophylaxis performed in the ROK Army since 1997 has contributed to the reduction in cases among military personnel. However, many prophylactic failure cases due to the resistance to the prophylactic regimen have been reportedsince 2000and twocases of chloroquine (CQ)-resistant P. vivax were reported, representing the first-known cases of CQ-resistant P. vivax from a temperate region of Asia. Delayed recrudescence, a kind of level I-resistance against CQ, has occurred frequently in DPRK. Continuous surveillance and monitoring are warranted to prevent further expansion of CQ-resistant P. vivax in ROKandDPRK.