Identification of factors associated with residual malaria transmission using school-based serological surveys in settings pursuing elimination

• Published in: Malaria Journal
• Main Authors: Jean Marius Rakotondramanga, Inès Vigan-Womas, Laura C. Steinhardt, Aina Harimanana, Elisabeth Ravaoarisoa, Tsikiniaina L. Rasoloharimanana, Seheno Razanatsiorimalala, Amy Wesolowski, Milijaona Randrianarivelojosia, Benjamin Roche, Andres Garchitorena
• Format: Article in Journal/Newspaper
• Language: English
• Published: BMC 2022
• Subjects: Malaria; Plasmodium falciparum; Antibody; Seroprevalence; AMA1; Spatial analysis; Arctic medicine. Tropical medicine; RC955-962; Infectious and parasitic diseases; RC109-216; Arctic
• Online Access: https://doi.org/10.1186/s12936-022-04260-0; https://doaj.org/article/9bf6e1b891ae49efa54ec5dbb96114b7

Abstract Background Targeted research on residual malaria transmission is important to improve strategies in settings pursuing elimination, where transmission reductions prove challenging. This study aimed to detect and characterize spatial heterogeneity and factors associated with Plasmodium falciparum infections and exposure, P. falciparum apical membrane antigen 1 (PfAMA1) antibody (Ab) response, in the Central Highlands of Madagascar (CHL). Methods From May to July 2014, a cross-sectional school-based survey was carried out in 182 fokontany (villages) within 7 health districts of the CHL. Rapid diagnostic tests (RDTs) and a bead-based immunoassay including PfAMA1 antigen biomarker were used to estimate malaria prevalence and seroprevalence, respectively. Local Moran’s I index was used to detect spatial “hotspots”. Remotely sensed environmental data—temperature, vegetation indices, land covers, and elevation—were used in multivariable mixed-effects logistic regression models to characterize factors associated with malaria infection and cumulative exposure. Results Among 6,293 school-children ages 2–14 years surveyed, RDT prevalence was low at 0.8% (95% CI 0.6–1.1%), while PfAMA1 Ab seroprevalence was 7.0% (95% CI 6.4–7.7%). Hotspots of PfAMA1 Ab seroprevalence were observed in two districts (Ankazobe and Mandoto). Seroprevalence increased for children living > 5 km from a health centre (adjusted odds ratio (OR) = 1.6, 95% CI 1.2–2.2), and for those experiencing a fever episode in the previous 2 weeks (OR 1.7, 95% CI 1.2–2.4), but decreased at higher elevation (for each 100-m increase, OR = 0.7, 95% CI 0.6–0.8). A clear age pattern was observed whereby children 9–10 years old had an OR of 1.8 (95% CI 1.2–2.4), children 11–12 years an OR of 3.7 (95% CI 2.8–5.0), and children 13–14 years an OR of 5.7 (95% CI 4.0–8.0) for seropositivity, compared with younger children (2–8 years). Conclusion The use of serology in this study provided a better understanding of malaria hotspots and associated factors, revealing ...