Malaria in the Republic of Korea, 1993–2007. Variables Related to Re-emergence and Persistence ofPlasmodium vivaxAmong Korean Populations and U.S. Forces in Korea

Abstract

Malaria was eradicated and the Republic of Korea (ROK) declared "malaria free" in 1979. However, in 1993, a temperate strain of vivax malaria, expressing both latent and nonlatent disease populations, re-emerged near the demilitarized zone (DMZ), rapidly spread to civilian sectors near the DMZ, and increased exponentially in ROK military, veteran, and civilian populations through 1998. Malaria among all ROK populations decreased 5-fold from a high of 4142 cases in 2000 to a low of 826 cases in 2004, before increasing again to 2180 cases by 2007. Each malaria case in the ROK is reported in the metropolitan area/province where the diagnosis is made, which may be at some distance from the area where infection occurred. Therefore, it is difficult to ascertain transmission sites since approximately 60% of vivax malaria in Korea is latent with symptoms occurring >1 month to 24 months after infection. A review of case diagnosis for civilian, veteran, and military populations shows that nearly all malaria south of Gyeonggi and Gangwon Provinces is the result of veterans exposed in malaria high-risk areas along the DMZ and returning to their hometowns where they later develop malaria. Thus, malaria currently remains localized near the DMZ with limited transmission in provinces south of Seoul and has not spread throughout Korea as previously hypothesized. This report describes the reemergence of vivax malaria cases in civilian and military ROK populations and U.S. military personnel and assesses variables related to its transmission and geographic distribution.

Geographic Structure of Plasmodium vivax: Microsatellite Analysis of Parasite Populations from Sri Lanka, Myanmar, and Ethiopia

“…However, the distinctive phenotypic features found in parasite populations from different countries suggests barriers to gene flow, or alternatively, strong selection maintaining differentiation at loci underlying these traits. 5 The ability of P. vivax malaria to re-emerge in regions where malaria eradication or control efforts in the past have been successful is already evident in countries such as Uzbekistan, 12 Azerbaijan, 13 the Republic of Korea 14 and northern Afghanistan. 15 Because of increased international travel and migration, the risk of re-introduction of P. vivax in areas where species of Anopheles with greater vectorial capacity are present is high.…”

Malaria in the Republic of Djibouti, 1998–2009

“…Among military service members, the United States experience in Korea, where the risk of malaria has been focal and well characterized in recent years, 32 has demonstrated that seasonal chemoprophylaxis targeted to only those populations at risk based on specific duty location is effective. 33 Such policies have the advantage of minimizing broader exposure to the risk of adverse events and inappropriate prescribing associated with chemoprophylaxis.…”

“…Although national travel guidelines specific to Djibouti currently recommend chemoprophylaxis, 16,17,29,30 authorities in the United States, France, Germany, and Japan suggest that deferment of chemoprophylaxis is reasonable in settings where cases of malaria occur sporadically and the risk of malaria transmission is very low, 29,31 and among certain expatriates and long-term travelers. [30][31][32] Since 2003, official guidance has recommended only seasonal chemoprophylaxis for French forces, and German authorities recommended similar guidance for its forces in 2008. When chemoprophylaxis is deferred, strict adherence to mosquito-avoidance measures, prompt evaluation and treatment of febrile illness, and universal availability of emergency standby treatment of those distant from medical care are strict necessities.…”

Mosquito Species Composition and Plasmodium vivax infection Rates for Korean Army Bases near the Demilitarized Zone in the Republic of Korea, 2011

“…populations are high throughout the ROK, the primary malaria threat has remained in northern Gyeonggi Province near the DMZ where transmission rates are high. [12][13][14] Reasons for the concentration of malaria along the DMZ are not well understood, although WHO reported that a malaria epidemic occurred in the Democratic People's Republic of Korea (DPRK, North Korea) shortly after the first case of malaria was reported in 1993 near the DMZ in the ROK, suggesting a parallel outbreak occurred in both countries. 15 Unique conditions in the vicinity of the DMZ, such as the exposure of large numbers of soldiers to malaria parasites and the unmanaged nature of the environment that encourages mosquito breeding, are thought to exacerbate the malaria situation.…”