[Epidemiologic study of malaria in the rice-growing regions of Yagoua and Maga (North Cameroon)].

The results of the malaria investigation carried out in April 1981 in the irrigated regions of the Logone Valley show that Plasmodium falciparum is the only species o. the genus Plasmodium to be found there. In terms of parasitaemia in blood, the prevalence of malaria is highest in the 5 to 9 year-old age group, whereas fluorescent antibodies are to be found progressively greater quantities as subjects grow older. From the age of 40, 95% of the inhabitants of the region present circulating antibodies in the blood. Plasmodial index of children from 2 to 9 years of age is equal to only 8.5% at the end of the dry season, whereas the spleen index, which is 34.8%, would suggest that malaria is meso-endemic in the region. With regard to the different sites studied, there is no significant difference in the values of the spleen or plasmodial indexes, either next to, or away from surface water. The malaria death rate is highest during the rainy months of August, September and October. The significant rise in the death rate during March corresponds to the concomitant rise in temperature. Entomological studies performed on the species of anophelines resting in the houses, which are gathered in the morning after a pulverization of insecticide, reveal that the dominant anopheline species in June is Anopheles gambiae, a species which, in the rainy season, abounds at water sites which are frequently temporary. On the other hand, in April, the dominant species is Anopheles funestus, which it would seem, develops easily during the dry season in those waterbodies which are artificially maintained all year round in the irrigated areas.