Abstract
BackgroundEpidemiological surveillance is a key activity in malaria control and elimination in low-transmission and pre-elimination settings. Hence, sensitive tools for estimating malaria force of infection are crucial. Serological markers might provide additional information in estimating force of infection in low-endemic areas along with classical parasite detection methods. Serological markers can be used to estimate recent, past or present malaria exposure, depending on the used markers and their half-life.MethodsAn assay based on 14 Plasmodium-specific peptides, one peptide specific for Anopheles gambiae saliva protein and five Plasmodium-specific recombinant proteins was developed for the MAGPIX system, assessed for its performance, and applied on blood spots from 2000 individuals collected in the Ratanakiri Province, Cambodia.ResultsA significant correlation for the use of 1000 and 2000 beads/antigen/well as well as for the monoplex versus multiplex assay was observed for all antigens (p < 0.05). For the majority of antigens, antigen-coupled beads were stable for at least 2 months. The assay was very reproducible with limited intercoupling, interplate and intraplate variability (mean RSD <15 %). Estimating seroconversion and seroreversion per antigen using reversible catalytic models and models allowing two seroconversion rates showed higher seroconversion rates in adults.ConclusionThe multiplex bead-based immunoassay was successfully implemented and analysis of field blood samples shows that changes detected in force of malaria infection vary according to the serological markers used. Multivariate analysis of the antibody responses and insights into the half-life of antibodies are crucial for improving the interpretation of these results and for identifying the most useful serological markers of past and recent malaria infection.Electronic supplementary materialThe online version of this article (doi:10.1186/s12936-015-0868-z) contains supplementary material, which is available to authorized users.
Highlights
Epidemiological surveillance is a key activity in malaria control and elimination in low-transmission and pre-elimination settings
Previous studies performed in low transmission settings, such as Cambodia, suggest that serological assays are promising for indicating malaria transmission [3, 10,11,12]
No clear ΔMFI signal was found for the positive control sera for Ags SR11.1, PvlikeCSP, PvVK210CSP, PvVK247CSP, PmCSP, SALIV1 and SALIV2 (ΔMFI < 1,500)
Summary
Epidemiological surveillance is a key activity in malaria control and elimination in low-transmission and pre-elimination settings. The low transmission rates in these areas pose considerable challenges for epidemiological surveillance [2], hindering the evaluation of new (vector) control tools necessary to reach elimination [1]. Serology is based on the detection of antibodies (Abs) against antigens (Ags) of malaria parasites, which offers an advantage as anti-Plasmodium Abs can persist for months after infection. These Abs have been suggested as indicators of malaria transmission [5,6,7,8], and are believed to be a better approach to determine past, recent and present malaria exposure [9]. Previous studies performed in low transmission settings, such as Cambodia, suggest that serological assays are promising for indicating malaria transmission [3, 10,11,12]
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