Development of in vitro microtest for the assessment of Plasmodium vivax sensitivity to chloroquine

An in vitro microtest to assess P. vivax sensitivity to chloroquine has been developed using a medium mixture which contained RPMI, Waymouth (GIBCO) and 15% (vol/vol) human serum group AB. The rate of success was highest in samples which were not washed by centrifugation before culturing in microtest plates predosed with varying concentrations of chloroquine. Evaluation of the effective concentration of chloroquine using a program for probit analysis of log dose/response test proved superior to simply using the percentage of schizont maturation.