A community study of T lymphocyte subsets and malaria parasitaemia.

In a community survey of 312 children aged 3-6 years in urban Guinea-Bissau, we examined Plasmodium falciparum parasitaemia and T cell subsets. 183 children (59%) had parasites in their blood, 13 had fever > or = 37.5 degrees C, and 9 (3%) had fever and a parasite density > 5000/microL (clinical malaria). Compared with children with no parasitaemia or asymptomatic parasitaemia, children with acute malaria had lymphopenia and significantly lower total CD4 and CD8 cell counts, but there was no significant difference in white blood cell count percentages of CD4 and CD8 cells, or the CD4/CD8 ratio. Children with parasitaemia but without fever had a significantly lower percentage of CD4 cells than children without parasites (P = 0.031), but did not differ in any other haematological index. Controlling for other factors, the CD4 cell percentage was inversely correlated with the density of malaria parasites (P = 0.024), whereas there was no association with CD8 cell percentage or the CD4/CD8 ratio. Asymptomatic parasitaemia may be an important confounder in general community studies of T cell subsets in the tropics.