In vitro drug sensitivity of Plasmodium falciparum in Acre, Brazil

ABSTRACT

In Acre, the westernmost state of Brazil in the Amazon ragion, the sensitivity of Plasmodium falciparum to chloroquine, amodiaquine, mefloquine, quinine and uslfadozine/pyrimethamine was determined in vitro by the Rieckmann microtechnique. The study was performed between January and June 1987; the in vitro parasite responses to all antimalarial drugs were determined according to the recommendations of WHO. Of 83 isolates of P. falciparum, all were sensitive to mefloquine and of 87 isolated of P. falciparum, 84 (97 per cent) were sensitive to quinine. The EC50 for mefloquine was 0.27 umol/1 and for quinine 4.60 umol/1. In contrast, 65 of 89 (73 per cent) and 70 of 83 (84 per cent) isolates were resistant to amodiaquine was 0.34 umol/1 and for chloroquine 0.73 umol/1. Sulfadoxine /pyrimethamine resistance was seen in 23 of 25 (92 per cent) cases