The roles of Plasmodium falciparum resistance to chloroquine and compliance in the protective efficacy of the antenatal chloroquine prophylaxis programme in Malawi were evaluated by interviewing pregnant women attending antenatal clinics and examining them for P. falciparum parasites in thick smears and chloroquine metabolites in urine. 36% of 642 women had urine chloroquine metabolite levels compatible with regular compliance to the weekly chloroquine dosage schedule. Among a subgroup of 288 pregnant women who were provided weekly prophylaxis under supervision for 4 consecutive weeks, P. falciparum infection rates were 37%, representing the failure of chloroquine to eliminate P. falciparum in Malawi. Among pregnant women not taking prophylaxis, the P. falciparum infection rate was 48%. Based on the P. falciparum infection rates among these 2 groups of women, the protective efficacy of CQ chloroquine was estimated as 23%. If the 36% of pregnant women who had chloroquine in their urines accurately estimates the proportion of women who comply with the prophylaxis programme in Malawi, the actual protective efficacy of the programme would be 8%. The cost of preventing one P. falciparum infection among pregnant women in the Malawi programme is estimated at US$ 10.87. This is an unacceptably high cost in much of Africa, and research is required to define more cost-effective interventions, including more effective drugs, and health education programmes to improve compliance among pregnant women.
PIP: During February-June 1988 in Malawi, interviews with and blood samples from 802 pregnant women attending 4 prenatal clinics on the shore of Lake Malawi or in the highlands were conducted to examine the role of chloroquine resistance and compliance in the protective efficacy of the government's chloroquine prophylaxis program. Compliance rates were 20% for women on their first prenatal visit and 36% for those on a return visit (i.e., urine chloroquine levels 1 ppm). 37% of 228 women who completed 4 weeks of supervised chloroquine administration had Plasmodium falciparum parasites in their blood. The P. falciparum infection rate was 48% among the 160 women who had not received supervised chloroquine administration. Based on these two rates, the protective efficacy of chloroquine was 23%. If the 36% of women on a return visit had taken their chloroquine as prescribed yet had chloroquine in their urine samples, the protective efficacy of the government's chloroquine prophylaxis program would have been 8%. Assuming an attack rate of P. falciparum of 48% and a protective efficacy of 8%, the cost per malaria case prevented would have been US $10.87. This is too high of a cost in Africa. Research is needed to identify more cost-effective interventions, such as more effective drugs and health education programs to improve compliance among pregnant women.