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 ≤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. © 2005 by the Infectious Diseases Society of America. All rights reserved.