Analysis of anti-Plasmodium IgG profiles among Fulani nomadic pastoralists in northern Senegal to assess malaria exposure

Abstract

Background: Northern Senegal is a zone of very low malaria transmission, with an annual incidence of < 5/1000 inhabitants. This area, where the Senegal National Malaria Control Programme has initiated elimination activities, hosts Fulani, nomadic, pastoralists that spend the dry season in the south where malaria incidence is higher (150-450/1000 inhabitants) and return to the north with the first rains. Previous research demonstrated parasite prevalence of < 1% in this Fulani population upon return from the south, similar to that documented in the north in cross-sectional surveys. Methods:A modified snowball sampling survey of nomadic pastoralists was conducted in five districts in northern Senegal during September and October 2014. Demographic information and dried blood spots were collected. Multiplex bead-based assays were used to assess antibody responses to merozoite surface protein (MSP-1 19 ) antigen of the four primary Plasmodium species, as well as circumsporozoite protein (CSP) and liver stage antigen (LSA-1) of Plasmodium falciparum. Results:In the five study districts, 1472 individuals were enrolled, with a median age of 22 years (range 1 to 80 years). Thirty-two percent of subjects were under 14 years and 57% were male. The overall seroprevalence of P. falciparum MSP-1 19 , CSP and LSA-1 antibodies were 45, 12 and 5%, respectively. Plasmodium falciparum MSP-1 19 antibody responses increased significantly with age in all study areas, and were significantly higher among males. The highest seroprevalence to P. falciparum antigens was observed in the Kanel district (63%) and the lowest observed in Podor (28%). Low seroprevalence was observed for non-falciparum species in all the study sites: 0.4, 0.7 and 1.8%, respectively, for Plasmodium ovale, Plasmodium vivax and Plasmodium malariae MSP-1. Antibody responses to P. vivax were observed in all study sites except Kanel.Conclusion: Prevalence of P. falciparum MSP-1 19 antibodies and increases by study participant age provided data for low levels of exposure among this transient nomadic population. In addition, antibody responses to P. falciparum short half-life markers (CSP and LSA-1) and non-falciparum species were low. Further investigations are needed to understand the exposure of the Fulani population to P. vivax.

Genomic investigation of atypical malaria cases in Kanel, northern Senegal

“…Malaria transmission in Senegal is highly seasonal with transmission occurring from July to December, and the main causative agent being P. falciparum [ 12 ]. Recent studies based on serologic data have shown the presence of P. vivax in the region of Matam [ 13 ], and Aedes mosquitoes competent for different dengue serotype transmission have also been isolated in the north [ 14 ].…”

Genomic investigation of atypical malaria cases in Kanel, northern Senegal

“…These patients given their age could have less exposure to the parasite, thus less immunity to GLURP which was shown to be correlated with malaria immunity in different studies [15], [16]. A high seroprevalence of P. falciparum MSP-1 19, CSP and LSA-1 antibodies was observed in the district of Kanel compared to the other districts in the north suggesting frequent exposure to P. falciparum [17]. However, the limited number of samples in this study are insu cient to provide an informative statistical analysis to appreciate the level of immunity in this village.…”

“…Senegal is highly seasonal with transmission occurring from July to December, and the main causative agent being P. falciparum [22]. Recent studies based on serologic data have shown the presence of P. vivax in the region of Matam [17], and Aedes mosquitoes competent for different dengue serotype transmission have also been isolated in the north [23].…”

Plasmodium falciparum Merozoite Associated Armadillo Protein (PfMAAP) Is Apically Localized in Free Merozoites and Antibodies Are Associated With Reduced Risk of Malaria

“…Our interest in the PF3D7_1035900 protein arose from a survey of the antigen-rich chromosome 10 cluster. A region that contains a number of well-characterized putative vaccine candidates including, the MSP3/6 protein family (18,19), GLURP (20,21), liver stage antigen 1 (22), to name but a few. In addition to its location, transcriptional data demonstrated a peak of expression at the late schizont/early merozoite stage (23,24), a profile that hinted at a biological importance for the late schizont and merozoite stages of the parasite.…”

“…The importance of this protein family is highlighted by their involvement in fundamental processes essential to parasite biology, including but not restricted to gene regulation and cytokinesis. Essential processes have been linked with the previously described P. falciparum ARM Repeats Only (PfARO) and P. falciparum Merozoite Organizing Proteins (PfMOP) (22), respectively. The putative function of PfARO has been assigned through studies using the Toxoplasma gondii paralog, TgARO (20,21).…”