Effects of HIV-1 serostatus, HIV-1 RNA concentration, and CD4 cell count on the incidence of malaria infection in a cohort of adults in rural Malawi.

BACKGROUND: To assess the effects of human immunodeficiency virus (HIV) infection on susceptibility to malaria, we compared the incidence rates of malaria by HIV type 1 (HIV-1) serostatus, baseline blood HIV-1 RNA concentration, and baseline CD4 cell count, over the course of a malaria season.
METHODS: We followed a cohort of 349 adults in Malawi. For the 224 HIV-1-seropositive adults (64% of the cohort), we measured HIV-1 RNA concentration (n=187) and CD4 cell count (n=184) at baseline. Parasitemia was defined as presence of asexual parasites on a thick film of blood and was treated with sulfadoxine/pyrimethamine (SP), in accordance with national policy. Hazard ratios (HRs) of parasitemia were estimated using Cox regression. Demographics were adjusted for.
RESULTS: HIV-1 seropositivity was associated with parasitemia (adjusted HR, 1.8 [95% confidence interval {CI}, 1.2-2.7] for a first parasitemia episode; adjusted HR, 2.5 [95% CI, 1.5-4.2] for a second parasitemia episode [> 14 days after the first episode]; adjusted HR, 1.9 [95% CI, 1.4-2.6] for parasitemia overall). Treatment failure (parasitemia < or = 14 days after SP treatment) did not differ by HIV-1 serostatus (risk ratio, 1.3 [95% CI, 0.5-3.2]). HIV-1 RNA concentrations and CD4 cell counts were moderately but inconsistently associated with parasitemia. A high parasite density with fever was associated with HIV-1 seropositivity and low CD4 cell count.
CONCLUSION: HIV-infected adults in malaria-endemic areas are at increased risk for malaria. Where possible, additional malaria prevention efforts should be targeted at this population.