Ineffectiveness of Amodiaquine against Plasmodium falciparum Malaria in Symptomatic Young Children Living in an Endemic Malarious Area of Papua New Guinea

Abstract

The standard in vivo 7-day test of drug resistance was conducted on 83 children with symptomatic P. falciparum infection, using a full 3-day course of amodiaquine. All children were living in an endemic malarious area of the East Sepik Province of Papua New Guinea. Analysis of blood amodiaquine levels by an ELISA method showed increased blood amodiaquine concentration with progressive days of treatment. By day 7 of the study period parasites had cleared in 68 (82 per cent) of the children while 15 (18 per cent) had persistence or recrudescence of P. falciparum. Of these 15 resistant cases, four were R1 resistant (early recrudescence), seven were R2, and four were R3. This is a higher proportion of R2/R3 resistance than has usually been reported in Papua New Guinea. In vivo amodiaquine resistance declined significantly with increasing age of the child. Resistance was found to be more common in children with low weight for age: this possible association requires further investigation in the study area, which has one of the highest rates of malnutrition in Papua New Guinea.