In vitro responses of P. falciparum parasites to chloroquine, amodiaquine and quinine in two ecological zones in Ghana.

Blood specimens were taken from 318 school children with at least 1,000 and not more than 80,000 P. falciparum asexual parasites per microliter of blood for a 30 hour in vitro microtest of P. falciparum asexual parasites responses to chloroquine, amodiaquine and quinine. The study was conducted in primary schools in four urban and three rural communities in the costal and forest zones in Ghana between June 1988 and December 1990. Chloroquine resistance was present in 58.7 pc (54/92) and 3.9 pc (4/103) of the successful in vitro tests in the coastal and forest zones respectively. Resistance to amodiaquine was recorded in 28.6 pc (12/42) of the successful tests in coastal zone. There was no resistance to quinine in any of the ecological zones. Concentrations of the three drugs in pmol required for 90 pc inhibition of schizont maturation were generally higher in communities in the coastal zone than those in the forest zone. The results suggest an increase in sensitivity or a reduction in resistance of P. falciparum to the drugs from the coast to the forest zone.