Bed net traps were used to collect anophelines from 1993 to 1996 [27, 32]

Bed net traps were used to collect anophelines from 1993 to 1996 [27, 32]. transmission intensity, but not for retrospective analysis of historical changes. Further investigation, including exploration of different malaria antigens and/or alternative models of population seroconversion, may yield serological tools that are more informative in high transmission settings. Electronic supplementary material The online version of this article (doi:10.1186/1475-2875-13-451) contains supplementary material, which is available to authorized users. Keywords: Malaria, parasites, is another common metric of malaria risk. Parasite prevalence is not a measure of incidence, however, and its relationship with force of infection is complicated by N-Acetylputrescine hydrochloride super-infection and acquired immunity [15]. Furthermore, estimates of parasite prevalence can vary widely in areas of seasonal transmission, and are influenced by the method of parasite detection, timing of measurement during the course of infection and access to anti-malarial drugs [13, 16, 17]. Anti-malarial antibodies are markers of past infection that can help to elucidate temporal trends in transmission [18, 19]. Because antibodies are longer N-Acetylputrescine hydrochloride lasting compared to patent parasitaemia and the lifespan of infective mosquitoes, serological tools are potentially more sensitive and robust than parasite prevalence or EIR. Large-scale serological surveys have proven useful in the past for examining impacts of interventions that reduce malaria parasite exposure. During the Garki Project in northern Nigeria, antibody prevalence and levels reflected recent changes in malaria exposure. Antibody responses fell abruptly during the intervention phase of the study, but rebounded soon after the intensive intervention was stopped [20]. More recently, by fitting a reversible catalytic conversion model to age-stratified seroprevalence data, investigators have estimated seroconversion rates (SCRs) that are analogous to force of infection [16, 18]. SCRs generated from several locations in Africa [16, 21, 22], Asia [23] and the Pacific [24] have shown close correlation with independent measures of transmission intensity such as malaria incidence among infants and young children, as well as averaged parasite prevalence and EIR values. Because serological markers provide information on cumulative exposure over time [25], they are particularly well suited for evaluating long-term transmission trends [16, 18]. Data from a single cross-sectional serological survey can, in theory, be used to generate a point estimate of the current force of infection as well as analyse historic changes in exposure to infection [16, 18]. Sero-epidemiological studies from Tanzania [21], Vanuatu [24], Equatorial Guinea [22], and Rabbit Polyclonal to AK5 Swaziland [26] have confirmed that historic reductions in local malaria transmission (e.g., due to successful control strategies) can be demonstrated by a significantly lower SCR among younger cohorts born after the intervention(s). In these cases, age-seroprevalence curves exhibited a break point signalling the timing of the change in SCR without the need for comparison against a baseline survey. To date, studies employing this method to reconstruct the timing and magnitude of transmission N-Acetylputrescine hydrochloride reduction have come from areas where transmission has dropped to low, sustained levels [21, 22, 24, 26]. It is unclear whether these serological tools are informative for reconstructing long-term malaria trends in regions of high transmission, where interventions may reduce transmission, but to a level where considerable exposure continues. The purpose of this study was to investigate the utility of serological markers of exposure for estimating force of malaria infection and detecting temporal changes in malaria risk over an extended period in a highly endemic setting. Asembo, in Western Kenya, has historically experienced intense malaria transmission year round [27]. A community-randomized, controlled insecticide-treated net (ITN) trial conducted from 1997 to 1999 drastically reduced malaria transmission [28, 29]. Following the trial, continued high ITN coverage.