Academic journal article Bulletin of the World Health Organization

Chemoprophylaxis and the Epidemiological Characteristics of Re-Emergent P. Vivax Malaria in the Republic of Korea

Academic journal article Bulletin of the World Health Organization

Chemoprophylaxis and the Epidemiological Characteristics of Re-Emergent P. Vivax Malaria in the Republic of Korea

Article excerpt

Voir page 833 le resume en francais. En la pagina 833 figura un resumen en espanol.

Introduction

Plasmodium vivax, the causative agent of vivax malaria, has been endemic in the Republic of Korea (ROK) for centuries. The number of cases of endemic malaria began to decline in the 1960s, partly due to increased socioeconomic development, increased use of agricultural pesticides, and the efforts of the National Malaria Eradication Service. These factors contributed to the eradication of malaria in the ROK, resulting in the declaration by WHO in 1979 that the country was malaria-free. (1) In 1993, one case of malaria attributed to autochthonous transmission was detected near the demilitarized zone (DMZ) that separates ROK (south) flora the Democratic People's Republic of Korea (north). (2) Since 1993, the number of malaria cases has increased exponentially, particularly among soldiers based near the DMZ. (1-5)

In ROK, healthy males aged over 18 years serve 26 months of mandatory military duty; most are stationed throughout their service near the DMZ, where the risk of malaria is highest. After finishing their military duty, the soldiers return from these risk areas to areas with little or no malaria. To reduce the occurrence of malaria among current and former soldiers, the military initiated antimalarial chemoprophylaxis in 1997.

Although chemoprophylaxis reduces the number of cases of malaria, long-term chemoprophylaxis can facilitate the development of drug resistance. (6,7) Recently, although there have been no reports of treatment failure in ROK, an increase in late primary episodes of P. vivax malaria among soldiers who had received chemoprophylaxis has raised doubts regarding its effectiveness. A recent study in ROK showed that prophylaxis with primaquine was not effective in preventing late primary attacks. (8)

We investigated the association between chemoprophylaxis and the epidemiological characteristics and effectiveness of treatment for re-emergent P. vivax malaria, using a nationwide malaria database.

Methods

Chemoprophylaxis

Chemoprophylaxis with hydroxychloroquine sulfate (400 mg, once per week) is started in early summer and continued throughout the transmission season. Fourteen-day prophylaxis with primaquine (15 mg of base, once per day) is started on the first day of the last week of chloroquine administration. During military duty, soldiers assigned to areas at risk of malaria experience two consecutive transmission seasons and receive chemoprophylaxis each season. In addition to chemoprophylaxis, in 1998 the military adopted the use of permethrin-treated battle-dress uniforms and bednets, and the application of mosquito vector-control agents. The number of soldiers receiving chemoprophylaxis and the amount of permethrin used have increased annually (Table 1).

Malaria surveillance

In ROK, malaria cases in soldiers must be reported to the Armed Forces Medical Command, and cases in veterans and civilians must be reported to the Korea Center for Disease Control and Prevention. (4,9) Malaria cases in veterans are defined as those experiencing a malaria attack within 24 months after retirement. Soldiers diagnosed with malaria are admitted to a military hospital for treatment and are interviewed by physicians; veterans are treated in community outpatient clinics and are interviewed by trained public-health specialists. All soldiers and veterans diagnosed with P. vivax malaria receive standard treatment: 2 g of hydroxychloroquine sulfate (1200, 400, and 400 mg on days 1 to 3, respectively) and 210 mg of primaquine (15 mg of base, once per day for 14 days).

Study subjects

We reviewed all cases of P. vivax malaria reported to the Armed Forces Medical Command and Korea Center for Disease Control and Prevention that occurred before 31 December 2003 in soldiers who had entered the ROK army during non-risk periods between 1 October 1998 and 28 February 2001 and who had been exposed to risk of malaria for the first rime in military service between 1999 and 2001. …

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