Malaria in Ile de Sainte Marie in 1988. Epidemiological approach. Chloroquine sensitivity of Plasmodium falciparum

The Malaria Research Unit of the Madagascar Pasteur Institute and the local health authorities carried out a study in the Sainte Marie Island in August 1988. Epidemiological results were in agreement with those previously reported in areas of endemic malaria. Parasite and splenomegaly rates were 34.6 and 35.9% respectively, by both active and passive cases detection. Analysis of parasite densities and clinical symptoms in the various age groups demonstrates that protective immunity is absent in infants and young children, and appears by the age of 2 to 9 years. An in vivo study of the sensitivity of Plasmodium falciparum to chloroquine was conducted in 41 patients. 39% of the infections were normally sensible (S) to WHO standard therapy (25 mg chloroquine/kg in 3 days), while 32% of the patients presented with a thick blood smear negative by D7, but positive by D14 (S/R1). Parasite resistance was observed in 29% of the infections: in 10% at the R1 level, and in 19% at the R2 level. Frequency and level of resistance to chloroquine are higher than those we observed in the East Coast in 1983 and 1985. However, chloroquine consistently achieves a high reduction in parasite densities and is still clinically active.