Low sensitivity to chloroquine and quinine of Plasmodium falciparum isolates from Guinea in March 1986.

An in vitro study performed using an isotopic method showed a decrease in susceptibility to chloroquine, quinine, and possibly mefloquine of 44 Plasmodium falciparum isolates collected in and around the city of Conakry in Guinea. Resistance to chloroquine was demonstrated by a mean EC99 at 149 nmol/l, above the cut-off value of 114 nmol/l. The mean EC99 for quinine reached 4,999 nmol/l; that is 5 times higher than that recorded in Gabon. Data collected in Guinea, where for many years drugs have been less readily available than in neighboring countries, do not suggest that drug pressure was essential for selecting resistant parasites.