Abstract
BackgroundAs The Gambia aims to achieve malaria elimination by 2030, serological assays are a useful surveillance tool to monitor trends in malaria incidence and evaluate community-based interventions.MethodsWithin a mass drug administration (MDA) study in The Gambia, where reduced malaria infection and clinical disease were observed after the intervention, a serological sub-study was conducted in four study villages. Spatio-temporal variation in transmission was measured with a panel of recombinant Pf antigens on a multiplexed bead-based assay. Village-level antibody levels were quantified as under-15 sero-prevalence, sero-conversion rates, and age-adjusted antibody acquisition rates. Antibody levels prior to MDA were assessed for association with persistent malaria infection after community chemoprophylaxis.ResultsSeasonal changes in antibodies to Etramp5.Ag1 were observed in children under 15 years in two transmission settings—the West Coast and Upper River Regions (4.32% and 31.30% Pf prevalence, respectively). At the end of the malaria season, short-lived antibody responses to Etramp5.Ag1, GEXP18, HSP40.Ag1, EBA175 RIII-V, and Rh2.2030 were lower amongst 1–15 year olds in the West Coast compared to the Upper River, reflecting known differences in transmission. Prior to MDA, individuals in the top 50th percentile of antibody levels had two-fold higher odds of clinical malaria during the transmission season, consistent with previous findings from the Malaria Transmission Dynamics Study, where individuals infected before the implementation of MDA had two-fold higher odds of re-infection post-MDA.ConclusionsSerological markers can serve dual functions as indicators of malaria exposure and incidence. By monitoring age-specific sero-prevalence, the magnitude of age-stratified antibody levels, or identifying groups of individuals with above-average antibody responses, these antigens have the potential to complement conventional malaria surveillance tools. Further studies, particularly cluster randomised trials, can help establish standardised serological protocols to reliably measure transmission across endemic settings.
Highlights
As The Gambia aims to achieve malaria elimination by 2030, serological assays are a useful surveillance tool to monitor trends in malaria incidence and evaluate community-based interventions
Outcomes included incidence of clinical disease, prevalence of Plasmodium falciparum (Pf) infection measured by polymerase chain reaction (PCR), and factors associated with infection post-mass drug administration (MDA)
Between July and December, sero-prevalence to Etramp5.Ag1 in children aged 1–15 years in the West Coast Region increased by 4.8%, by 3.1% for PfMSP119, by 2.9% for PfGLURP.R2, and by 2.2% for gametocyte export protein 18 (GEXP18) (Table 1, Fig. 2, Additional file 1 - Supplementary Table 1)
Summary
As The Gambia aims to achieve malaria elimination by 2030, serological assays are a useful surveillance tool to monitor trends in malaria incidence and evaluate community-based interventions. Large proportions of the population can remain malaria free for years, while subpopulations experience multiple episodes [3, 4, 6]. This presents significant challenges for the implementation of malaria interventions and clinical trials designed to evaluate them [7, 8]; if untargeted, residual transmission is likely to persist [5, 9,10,11]. Micro-epidemiological variations in transmission remain [18, 19], which are increasingly relevant as The Gambia aims for malaria elimination by 2030. Sensitive diagnostics will be critical to reach this target, helping to identify foci of transmission and target interventions
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call