Resistance of Plasmodium falciparum malaria to amodiaquine, chloroquine and quinine in the Madang Province of Papua New Guinea, 1990-1993.

ABSTRACT

PIP: The in vivo response of Plasmodium falciparum parasites to amodiaquine and chloroquine was assessed in children 1-9 years of age with symptomatic malaria recruited from health centers in Papua New Guinea's Madang area. Among the 27 children who were completely followed up, 4 (15%) were infected with fully susceptible parasites; in the remaining 23 cases (85%), there was some degree of resistance. 52% of parasites in the latter group were RI level, 26% RII, and 22% RIII. There was no correlation between level of resistance and age. 14 out of 42 children (33%) failed to clear their parasitemia by day 7 and 92 out of 134 (69%) had persistent or recrudescent parasitemia at day 21. Both amodiaquine and chloroquine had similar levels of in vivo resistance. 86% of isolates tested in vitro showed resistance to amodiaquine, 86% to chloroquine, and 7% to quinine. In 10 years, the prevalence of resistant isolates in vivo has increased from 47% to 85%. Of particular concern is the finding that the proportion of resistant strains that were RI dropped from 90% to 52% over this decade. The increase of resistance is attributed to indiscriminate use of 4-aminoquinolines in all cases of fever. Needed, to assess whether standard antimalarial regimens are still appropriate, is a review of treatment failure in different parts of Papua New Guinea.