A study of the sensitivity of Plasmodium falciparum to chloroquine and mefloquine using the in vitro microtechnique in Peninsular Malaysia.

Plasmodium falciparum drug sensitivities to chloroquine and mefloquine were assessed with WHO in vitro microtechnique test kits in 5 localities near the border with Thailand in Peninsular Malaysia. 105 of 113 (92.9%) parasite isolates were successfully tested and 103 (98.1%) showed resistance to chloroquine with parasite growth even at greater than or equal to 5.7 pmol of the drug. All these isolates were sensitive to mefloquine, parasite growth being inhibited at less than or equal to 11.3 pmol of the drug.