Implications of malarial endemicity in East Africa

Abstract

1. 1. A summary is given of the results of a survey of a typical fully immune Bantu community, and attention is drawn to the great frequency (thirty times a year) of infection by anopheles which occurs under such circumstances. 2. 2. In other areas, having almost the same spleen rate, such a degree of immunity does not occur, and this is found to be associated with a much lower frequency of infection of anopheles (four to eight times a year). 3. 3. The essential difference in the endemic state of these two communities is clearly revealed by a comparison of the adult parasite counts, and of the seasonal variation in the parasite counts. These and other indices found in the less immune community are given in full. 4. 4. While in the first case anopheline control is economically impossible, reasons are given for concluding that it is worth attempting in the second—where malaria is seasonal. 5. 5. Since a fully immune adult shows no signs of illness attributable to malaria, he should not be given treatment for the few parasites he may carry, and babies should only be given enough treatment to remove danger to life: the object in both cases being to interfere as little as possible with the state of full immunity. 6. 6. Where on the other hand immunity is incomplete, treatment will have to be given for the clinical attacks which occur both in children and adults. Treatment should not however aim at eradication of infection, since there is an appreciable degree of immunity present, and this can only be maintained by the stimulus of persistent infection. 7. 7. Reference is made to some of the problems which are affecting non-immune Africans. 8. 8. The parasite of clinical malaria is P. falciparum, and the variations in immunity refer, to all intents and purposes, only to P. falciparum. 9. 9. Variation in the appearances of P. falciparum in immunes and in non-immunes has been observed, and is described.