CHLOROQUINE-RESISTANT PLASMODIUM-VIVAX IN TRANSMIGRATION SETTLEMENTS OF WEST KALIMANTAN, INDONESIA

Malariometric surveys were conducted during July 1996 in native Dayak villages and predominantly Javanese transmigration settlements in Keta pang district of West Kalimantan, Indonesia. Malaria prevalence ranged from 0.9% to 2.7% in Dayak villages and from 1% to 20% in the transmi gration settlements. Plasmodium falciparum accounted for 67% of the ca ses among Dayaks but P. vivax was dominant among transmigrants, accoun ting for more than 72% of the infections. Chloroquine sensitivity/resi stance was assessed by 28-day in vivo testing of uncomplicated malaria infections and measurement of chloroquine blood levels in cases where parasitemias reappeared within the 28-day test period. Resistance was based on the appearance of asexual parasites against chloroquine plus desethylchloroquine levels exceeding the minimally effective whole bl ood concentrations proposed for sensitive parasite strains (P. vivax, 100 ng/ml; P. falciparum, 200 ng/ml). All parasitemias cleared initial ly within four days of beginning supervised chloroquine therapy (25 mg base/kg over a 48-hr period), but asexual parasites reappeared within 28 days in 27 of 52 P. vivax and three of 12 P. falciparum cases. Chl oroquine blood levels at the time of recurrent parasitemias revealed r esistance in 12 of the 27 P. vivax cases and in one of the three P. fa lciparum cases. Genotypes of nine of the 12 recurrent P. vivax isolate s matched with their primary isolates and ruled out reinfection. These findings establish the presence of chloroquine-resistant P. vivax on the island of Borneo. The pattern of malaria and the high frequency of chloroquine resistance by P. vivax at the West Kalimantan location ma y relate to demographic, ecologic, agricultural, and socioeconomic cha nges associated with transmigration.