Malaria and intestinal parasites co-infections: Antibody response to malaria vaccine candidate antigens in children

Ndiabamoh Crespo'o Mbe-cho (crespo.ndiabamoh@yahoo.com)
Microbiologie / parasitologie / hématologie /immunologie, University of Yaoundé 1
June, 2017
 

Abstract

Malaria/intestinal parasites co-infections are a very common condition in children in Africa with an impact on the host humoral immune system. However, little information is available about whether and how co-infections of intestinal parasites and malaria affect specific immune response to malaria vaccine candidate antigens. We sought to determine the impact of malaria and intestinal parasites co-infections on humoral response to malaria vaccine candidate antigens.
We carried out a cross sectional analytic study from October 2016 to April 2017 in children aged 1-15 years whose parents and guardian gave consent in Ngali and Mfou, two villages in central Cameroon. Peripheral blood was collected. An onsite rapid diagnostic test (RDT) and haemoglobin measurements was done. Fresh stool samples were equally collected. Wet mount, Kato-Katz method and Modified RIETCHI concentration techniques were used to analyse stools. Blood smear microscopy was later used for confirmation and speciation of malaria. The MagPix Multiplex Analyte Platform (MAP) assay was used for antibody study.
Of the 320 children enrolled, the mean age was 7.8 ± 3.6 years and the mean weight was 27.4 (6-75) kg. The prevalence of malaria in Ngali and Mfou was 80.7% and 72.8%, while that for co-infections was 42.1% and 17.8% respectively, a majority being between the age range 6-10 years. The predominant species was plasmodium falciparum (93.3%). The combined mean parasitemic density was 12775±3316 parasites per microliters. 44.3% of malaria positive children had anaemia. All children with malaria had high anti-MSP142, MSP2FC27, MSP3Ec and EBA175 antibody levels, with the highest of these values being observed in children age 1-5 years. Also there was an up-regulation of antibodies levels against antigens in malaria co-infected children. These co-infected children had a positive correlation between age, parasitemias and all antibody levels. Finally, there was positive and significant correlations between haemoglobin and antibody levels against MSP2FC27, MSP3Ec and EBA175.
1) The general prevalence of malaria was 76% and co-infections 17% in our study cohort. The prevalence of malaria in Ngali and Mfou was 80.7% and 72.8%, while that for co-infections was 42.1% and 17.8% respectively during the transitional dry to rainy season.
2) An up-regulation in the malaria and intestinal parasite co-infection group against EBA175, MSP2FC27 and MSP3Ec was observed.
3) Co-infections boosted antibody production against malaria and mostly in children aged 1-5 years.
4) A significant and positive correlations between age, haemoglobin levels and antibody levels was observed.
Key words: malaria, intestinal parasites, co-infections, antibody, vaccine, children.


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