Effect of cotrimoxazole prophylaxis on the incidence of malaria in HIV-infected children in 2012, in Abidjan, Côte d’Ivoire: a prospective cohort study

BACKGROUND Cotrimoxazole prophylaxis has an antimalarial effect which could have an additional protective effect against malaria in HIV-infected children on antiretroviral therapy (ART). We measured the incidence and associated factors of malaria in HIV-infected children on ART and/or cotrimoxazole in Abidjan, Côte d'Ivoire. METHODS All HIV-infected children <16 years, followed-up in the IeDEA West-African paediatric cohort (pWADA) in Abidjan, were prospectively included from May to August 2012, the rainy season. Children presenting signs suggesting malaria had a thick blood smear and were classified as confirmed or probable malaria. We calculated incidence density rates (IR) per 100 child-years (CY). Risk factors were assessed using a Poisson regression model. RESULTS Overall, 1117 children were included, of whom 89 % were ART-treated and 67 % received cotrimoxazole. Overall, there were 51 malaria events occurring in 48 children: 28 confirmed and 23 probable; 94 % were uncomplicated malaria. The overall IR of malaria (confirmed and probable) was 18.3/100 CY (95 % CI: 13.3-23.4), varying from 4.2/100 CY (95 % CI: 1.1-7.3) in children on ART and cotrimoxazole to 57.3/100 CY (95 % CI: 7.1-107.6) for those receiving no treatment at all. In univariate analysis, age < 5 years was significantly associated with a 2-fold IR of malaria compared to age >10 years (incidence rate ratio [IRR] = 2.18, 95 % CI: 1.04-4.58). Adjusted for severe immunodeficiency, cotrimoxazole reduced significantly the IR of first malarial episode (adjusted IRR [aIRR] = 0.13, 95 % CI: 0.02-0.69 and aIRR = 0.05, 95 % CI:0.02-0.18 in those off and on ART respectively). Severe immunodeficiency increased significantly the malaria IR (aIRR = 4.03, 95 % CI: 1.55-10.47). When considering the IR of confirmed malaria only, this varied from 2.4/100 CY (95 % CI: 0.0-4.8) in children on ART and cotrimoxazole to 34.4/100 CY (95 % CI: 0.0-73.3) for those receiving no treatment at all. In adjusted analyses, the IR of malaria in children on both cotrimoxazole and ART was significantly reduced (aIRR = 0.05, 95 % CI: 0.01-0.24) compared to those receiving no treatment at all. CONCLUSIONS Cotrimoxazole prophylaxis was strongly protective against the incidence of malaria when associated with ART in HIV-infected children. Thus, these drugs should be provided as widely and durably as possible in all HIV-infected children <5 years of age.