[Plasmodium falciparum and drepanocytic gene in Popular Republic of Congo. I. Prevalence of malaria and drepanocytic trait among school children in Brazzaville area (author's transl)].

From 1978 to 1979, 5 surveys, among schoolchildren, were carried out during the rainy season in the neighbourhood of Brazzaville (R.P. Congo): 3 in PK 45 village (northern part of the capital), 2 in Djoumouna village (southern part), and 1 in "Talangai" (a suburb of the capital). 868 exams (plasmodic and splenic index fitted with hemoglobin composition [Hb AA or Hb AS]) were done. It appeared that 19,6% of schoolchildren examined were heterozygous sicklers (AS). This percentage confirmed the previous results from other authors in different countries of Central Africa. On the other hand, in spite of an intense transmission, both plasmodic and splenic index were, on the average, relatively low (24,5 and 24,8% respectively). Plasmodium falciparum was largely predominant (95,3% of infections) but P. ovale and P. malariae were also found (1,9% for each species). From our study no obvious "protecting effect" can be attributed to sickle cell trait because plasmodic index of children AA and AS were similar (23,8 and 27,6% respectively). A slight decrease of splenic index was noticed in AS in regard to AA (19,4 and 26.1% respectively). It is difficult to consider this no significative regression as a definitive proof of a premunition stronger in AS than in AA. Effectively some splenic infarctus are well known to be a regular physiopathological process occurring in homozygous SS but often in heterozygous AS too. In such highly endemic and stable malaria area the problem of a suitable antimalaria strategy remains to be solved.