Malaria transmission and individual variability of the naturally acquired IgG antibody against the Plasmodium vivax blood-stage antigen in an endemic area in Brazil.

Plasmodium vivax remains an important cause of malaria in South America and Asia, and analyses of the antibody immune response are being used to identify biomarker of parasite exposure. The IgG antibody naturally acquired predominantly occurs against targets on blood-stage parasites, including C-terminal of the merozoite surface protein 1 (MSP1-19). Epidemiological and immunological evidence has been showed that antibodies to malaria parasite antigens are lost in the absence of ongoing exposure. We describe the IgG antibody response in individuals living in an unstable malaria transmission area in Pará state, Amazon region, Brazil, where an epidemic of P. vivax malaria was recorded and monitored over time. As indicated by epidemiological data, the number of P. vivax-caused malaria cases decreased by approximately 90% after three years and the prevalence of IgG positive to PvMSP1-19 decreased significantly over time, in 2010 (93.4%), 2012 (78.3%), and 2013 (85.1%). Acquisition and decay of the IgG antibody against P. vivax MSP1-19 showed variability among individuals living in areas with recent circulating parasites, where the malaria epidemic was being monitored until transmission had been completely controlled. We also found that previous malaria episodes were associated with an increased in the IgG positivity . Our results showed epidemiological, spatial, temporal and individual variability. The understanding on dynamics of antibodies may have implications for the design of serosurveillance tools for monitoring parasite circulation, especially in a context with spatial and temporal changes in P. vivax malaria transmission.