PLASMODIUM-FALCIPARUM INDEX AND LEVEL OF PARASITEMIA - DIAGNOSIS AND PROGNOSTIC VALUE IN CONGOLESE SUBJECTS

Parasitological data of various malarial studies performed in the Cong o where Plasmodium falciparum malaria is holoendemic in rural and subu rban zones, between 1988 and 1991. were analyzed with the intention of establishing diagnosis and prognosis value or Plasmodium falciparum p arasitaemia in areas with high perennial transmission. In such an area congolese schoolchildren (6-10 years old) had 88% P. falciparum index , this is the same percentage as that for children hospitalized with a pernicious attack. However, the parasite load is distributed differen tly; parasitaemia is greater than 6,000 asexual form of P. falciparum/ mu l (afPf/mu L) in only 4.6% of cases in the former group versus 67% in the second group. A threshold of 10,000 afPf/mu l, above which the Plasmodium infection triggers a febrile attack in semi-immune children , is confirmed in school children in a rural context where the factor of taking antimalarial drugs within the preceding days is negligible; three out of four children with levels above this threshold are febril e versus 4.1% (7 out of 170) with lower blood parasite levels. Some ad ults were also asymptomatic carriers but much less frequently and with lower mean parasitaemia levels. The parasite load mirrors the clinica l severity although this concept can be misleading as an individual pr ognostic criterion and for hospital studies carried out in areas where multiple drug administration before hospitalisation is common. For th e studies recently performed in Brazzaville, the 5% threshold level of parasitized red cells, the WHO severity criterion, was never reached in asymptomatic subject or in cases of simple attack; it was reached i n one out of two cases of pernicious attack.