TY - JOUR
T1 - Identification of factors associated with residual malaria transmission using school-based serological surveys in settings pursuing elimination
AU - Rakotondramanga, Jean Marius
AU - Vigan-Womas, Inès
AU - Steinhardt, Laura C.
AU - Harimanana, Aina
AU - Ravaoarisoa, Elisabeth
AU - Rasoloharimanana, Tsikiniaina L.
AU - Razanatsiorimalala, Seheno
AU - Wesolowski, Amy
AU - Randrianarivelojosia, Milijaona
AU - Roche, Benjamin
AU - Garchitorena, Andres
N1 - Funding Information:
This work was supported by the US President’s Malaria Initiative program (Grant Number AID- 687-G-13-00003 Surveillance and Data for Management Project) and the Institut Pasteur de Madagascar.
Funding Information:
The authors would like to thank to the population of the districts and communes investigated and especially to the children, parents, who participated to the study. We also thank those who facilitated the survey that is heads of communes and fokontany , local administration authorities, and health authorities from Ministry of Public Health of Madagascar. We also thank the National Malaria Control Program and Institut Pasteur de Madagascar survey teams. We especially thank Sixte Zigirumugabe and Jessica Butts of the US President’s Malaria Initiative for their guidance in aligning the assessment to on the ground management decisions; Christophe Rogier, Patrice Piola and Thomas Kesteman for their respective valuable advices and input on the study methodology and lab analyses of samples; Anny Randriamoramanana and Bienvenue RAHOILIJAONA for helpful support on data management supports; and Anthonio RAKOTOARISON and Daouda KASSIE for remotely sensed data analysis advices.
Publisher Copyright:
© 2022, The Author(s).
PY - 2022/12
Y1 - 2022/12
N2 - 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 a pattern of higher transmission linked to geographical barriers in health care access. The integration of antibody-assays into existing surveillance activities could improve exposure assessment, and may help to monitor the effectiveness of malaria control efforts and adapt elimination interventions.
AB - 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 a pattern of higher transmission linked to geographical barriers in health care access. The integration of antibody-assays into existing surveillance activities could improve exposure assessment, and may help to monitor the effectiveness of malaria control efforts and adapt elimination interventions.
KW - AMA1
KW - Antibody
KW - Cluster
KW - Epidemiology
KW - Madagascar
KW - Malaria
KW - Plasmodium falciparum
KW - Seroprevalence
KW - Spatial analysis
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U2 - 10.1186/s12936-022-04260-0
DO - 10.1186/s12936-022-04260-0
M3 - Article
C2 - 35989358
AN - SCOPUS:85137008780
SN - 1475-2875
VL - 21
JO - Malaria journal
JF - Malaria journal
IS - 1
M1 - 242
ER -