Prevalence of malaria exhibiting reduced sensitivity to chloroquine in Southern Thailand

Abstract

A study to determine the approximate prevalence of malaria parasites exhibiting reduced sensitivity to 4 mg of chloroquine base per lb body weight was undertaken in the Self-Help Land Settlements of Satul, Yala and Narathivas Provinces, Southern Thailand. A further study to determine the approximate prevalence of malaria parasites exhibiting reduced sensitivity to a therapeutic course of 10 mg per lb of base was conducted. The data indicated that in approximately 79% of the 307 cases with P. falciparum infections the parasites showed reduced sensitivity to 4 mg per lb of the drug, and in approximately 53% of the 111 school children with P. falciparum the parasites exhibited reduced sensitivity to 10 mg per lb. The 4 cases of simple P. vivax infection was highly sensitive to chloroquine. The 3 mixed (P. falciparum and P. vivax) infections reverted to simple infections with P. falciparum. A recommendation to evaluate the usefulness of chloroquine in all malaria eradication and control programs is proposed.