Prevalence and Risk Factors of Baseline Plasmodium Infection before the First Seasonal Malaria Chemoprevention Round in Burkina Faso: A Cross-Sectional Study
Background: Malaria parasite carriage represents a hidden reservoir that sustains transmission and may undermine the effectiveness of control strategies such as seasonal malaria chemoprevention (SMC). Quantifying the prevalence and risk factors of parasite carriage prior to SMC delivery could provide essential baseline data for assessing the impact of the intervention and optimizing its implementation. Methods: A cross-sectional survey was conducted in July 2025, 0 to 4 days before delivery of the first round of SMC. Children were randomly selected from ten villages in the Nanoro Health and Demographic Surveillance System (HDSS). Capillary blood was collected by finger prick to prepare thick and thin blood smears, which were examined later by light microscopy to detect Plasmodium species carriage. Socio-demographic and household characteristics were extracted from the HDSS database. Associations between covariates including child age, sex, mid upper arm circumference, household head education, malaria prevention practices, and household wealth quintile and Plasmodium carriage were assessed using modified Poisson regression with robust variance, fitted with generalized estimating equations to estimate prevalence ratios and 95% confidence intervals. An exchangeable working correlation structure was specified, with clustering at the household level to account for intra household intra correlation. Results: Among 1,643 enrolled children with microscopy results, the prevalence of Plasmodium carriage was 25.5% (95% CI: 23.5% - 27.7%) and that of gametocyte carriage was 2.2% (95% CI: 1.6 - 3.1). Compared to children aged < 1 year, the risk of carriage was higher in those aged 2 - 3 years (aPR 3.03; 95% CI: 1.98 - 4.63), and 3 - 4 years (aPR 3.43; 95% CI: 2.25 - 5.23). Male children had higher prevalence ratio than females (aPR = 1.21; 95% CI: 1.03 - 1.42). Conclusion: Prior to SMC campaign, Plasmodium carriage was prevalent among children in Nanoro, with older children exhibiting significantly higher risk. These findings emphasize the relevance of SMC intervention at that period of the year and complementary interventions, such as vaccination and targeted health education, alongside the SMC implementation. This baseline data informs tailored strategies in high-transmission settings.
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