Plasmodium falciparum sensitivity to antimalarials at Humera, northwestern Ethiopia

Between September 5 and 25, 1991, the susceptibility of P. falciparum to chloroquine and sulfadoxine-pyrimethamine (SP) was measured in vivo in 47 semi-immune cases at Humera-Northwestern Ethiopia using the simplified in vivo test. The objective of the study was to obtain baseline data, and to suggest first and second line drugs. A 25mg/kg dose of chloroquine base was administered over a three-day period to 23 cases of P. falciparum malaria with a minimum of 25 rings/300 white blood cells. All showed results consistent with sensitivity. The same was true for all 24 cases who received a single curative dose of SP. None of the cases had recrudescence within seven days follow-up, indicating that RII and RIII levels of resistance were absent. Further follow-up using the extended test (28 days) was not carried out since transmission cannot be excluded under field conditions and recrudescence cannot always be distinguished from reinfection. Although it was impossible to distinguish between sensitivity and RI level of resistance, it was concluded that chloroquine is still effective and the drug of choice in the area studied, while SP is a possible first line alternative.