Serological evidence of vector and parasite exposure in Southern Ghana: the dynamics of malaria transmission intensity
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Date
2015
Journal Title
Journal ISSN
Volume Title
Publisher
BioMed Central
Abstract
Background: Seroepidemiology provides robust estimates for tracking malaria transmission when intensity is low
and useful when there is no baseline entomological data. Serological evidence of exposure to malaria vectors and
parasite contribute to our understanding of the risk of pathogen transmission, and facilitates implementation of
targeted interventions. Ab to Anopheles gambiae salivary peptide (gSG6-P1) and merozoite surface protein one
(MSP-119) reflect human exposure to malaria vectors and parasites. This study estimated malaria transmission
dynamics using serological evidence of vector and parasite exposure in southern Ghana.
Methods: Total IgG responses to both antigens in an age stratified cohort (<5, 5–14, >14) were measured from
South-eastern Ghana. 295 randomly selected sera were analyzed from archived samples belonging to a cohort study
that were followed at 3 consecutive survey months (n = 885); February, May and August 2009. Temporal variations in
seroprevalence of both antigens as well as differences between the age-stratified cohorts were determined by χ2 test
with p < 0.05 statistically significant. Non-parametric repeated ANOVA – Friedman’s test was used to test differences in
antibody levels. Seroprevalence data were fitted to reversible catalytic model to estimate sero-conversion rates.
Results: Whereas parasite prevalence was generally low 2.4%, 2.7% and 2.4% with no apparent trends with
season, seroprevalence to both gSG6-P1 and MSP119 were high (59%, 50.9%, 52.2%) and 57.6%, 52.3% and 43.6%
in respective order from Feb. to August. Repeated measures ANOVA showed differences in median antibody levels across
surveys with specific significant differences between February and May but not August by post hoc Dunn’s
multiple comparison tests for gSG6-P1. For MSP119, no differences were observed in antibody levels between
February and May but a significant decline was observed from May to August. Seroconversion rates for gSG6-P1
increased by 1.5 folds from February to August and 3 folds for MSP119.
Conclusion: Data suggests exposure to infectious bites may be declining whereas mosquito bites remains high.
Sustained malaria control efforts and surveillance are needed to drive malaria further down and to prevent
catastrophic rebound. Operational factors for scaling up have been discussed.
Description
An article published by BioMed Central and also available at DOI 10.1186/s13071-015-0861-y
Keywords
Anopheles gambiae, Salivary peptide, Malaria exposure, Seroprevalence, Seroconversion rate, Merozoite surface protein, Parasite prevalence
Citation
Badu et al. Parasites & Vectors (2015) 8:251. Serological evidence of vector and parasite exposure in Southern Ghana: the dynamics of malaria transmission intensity. DOI 10.1186/s13071-015-0861-y