Effect of HIV-1 and increasing immunosuppression on malaria parasitaemia and clinical episodes in adults in rural Uganda: a cohort study

Background An association between HIV-1 and malaria is expected in theory, but has not been convincingly shown in practice. We studied the effects of HIV-1 infection and advancing immunosuppression on falciparum parasitaemia and clinical malaria. Methods HIV-1-positive and HIV-1-negative adults selected from a population-based cohort in rural Uganda were invited attend a clinic every 3 months (routine visits) and whenever they were sick (interim visits). At each visit, information was collected on recent fever, body temperature, and malaria parasites. Participants were assigned a clinical stage at each routine visit and had regular CD4-cell measurements. Findings 484 participants made 7220 routine clinic visits between 1990 and 1998. Parasitaemia was more common visits by HIV-1-positive individuals (328 of 2788 [11·8%] vs 231 of 3688 [6·3%], p<0·0001). At HIV-1-positive visits, lower CD4-cell counts were associated with higher parasite densities, compared with HIV-1-negative visits (p=0·0076). Clinical malaria was significantly more common at HIV-1-positive visits (55 of 2788 [2·0%] vs 26 of 3688 [0·7%], p=0·0003) and the odds of having clinical malaria increased with falling CD4-cell count (p=0·0002) and advancing clinical stage (p=0·0024). Participants made 3377 interim visits. The risk of clinical malaria was significantly higher at visits by HIV-1-positive individuals than HIV-1-negative individuals (4·0% vs 1·9%, p=0·009). The risk of clinical malaria tended increase with falling CD4-cell counts (p=0·052). Interpretation HIV-1 infection is associated with an increased frequency of clinical malaria and parasitaemia. This association tends to become more pronounced with advancing immunosuppression, and could have important public-health implications for sub-Saharan Africa.