IN-VIVO RESISTANCE TO CHLOROQUINE BY PLASMODIUM-VIVAX AND PLASMODIUM-FALCIPARUM AT NABIRE, IRIAN-JAYA, INDONESIA

A survey of resistance to chloroquine by Plasmodium vivax and P. falci parum was conducted during May 1995 at three mesoendemic villages 30 k m southeast of Nabire, near the central northern coast of Irian Jaya, Indonesia. The prevalence of malaria at Urusumu (n = 157), Margajaya ( n = 573), and Topo (n = 199) was 18%, 9%, and 9%, respectively, with s pleen rates among children of 79%, 10%, and 27%. Infected patients amo ng those screened formed a study population of 64 subjects eligible fo r a 28-day in vivo test of resistance to chloroquine. Sixty-three pati ents successfully completed the test; 45 males and 18 females 1-60 yea rs of age, of whom 29 were Javanese transmigrants of five years reside nce in Irian Jaya and 34 were native to Irian Jaya. The seven-day day cumulative incidence of therapeutic failure for P. vivax and P. falcip arum was 15% (n = 34) and 30% (n = 37). The 14- and 28-day estimates o f cumulative incidence were 45% and 64% for P. vivax and 58% and 89% f or P. falciparum. Almost ail recurrences appeared in the face of ordin arily effective levels of chloroquine and its major metabolite, deseth ylchloroquine, in whole blood (greater than or equal to 100 ng/ml). Fo ur infections by P. malariae in subjects enrolled in this study cleare d by day 2 and none reappeared within 28 days. Chloroquine no longer p rovides effective therapy for falciparum or vivax malaria along the no rthern coast of Irian Jaya, Indonesia.