Seroprevalence of Antibodies to Plasmodium spp. among Individuals without Detectable Infection in Etsako, Edo State, Nigeria
Authors: Olaniyan Mathew Folaranmi , Adeoye Felix Abayomi , Tijani Wakili Adelani , Olaniyan Tolulope Busayo , Ajiboye Kemi Felicia , Adeniran Medinat Taiwo , Ugege Christian Onosetale , Adebo David Olufemi , Akpoyovwere Obataze Josephine , Odegbemi Odekunle Bola 
Published: February 2025

Abstract

Background:
Malaria remains a significant public health challenge, particularly in Sub-Saharan Africa. Plasmodium falciparum, the most virulent malaria parasite, continues to cause considerable morbidity and mortality globally. Understanding the prevalence of antibodies against Plasmodium provides critical insights into population immunity and informs effective control strategies.

Aim:
This study aimed to assess the prevalence of harvestable antibodies to Plasmodium among individuals without detectable Plasmodium spp. in the Etsako region of Edo State, Nigeria. What is the prevalence of harvestable antibodies to Plasmodium among individuals without detectable Plasmodium spp. in the Etsako region of Edo State, Nigeria, specifically in the towns of Elele and Iyamho? Specifically, the towns of Elele and Iyamho were investigated because of their reported low mosquito burdens, which may influence malaria transmission dynamics and immunity.

Materials and Methods:
A cross-sectional study was conducted involving 500 adults (250 females, 50%) aged 18–65 years from Elele and Iyamho in the Etsako region. The participants were selected through a multistage random sampling technique to ensure a representative sample of the population. Serum samples were collected and analyzed through an enzyme-linked immunosorbent assay for anti-Plasmodium antibodies. The data were analyzed through descriptive (mean, median, and percentages) and inferential statistics (Chi-square tests and logistic regression) to explore associations between antibody levels and sociodemographic variables.

Results:
Of the 500 participants, 78% (390/500) had detectable anti-Plasmodium antibodies, with an approximately 76% (190/250) prevalence in males and an 80% (200/250) prevalence in females. Antibody levels varied between low (30%), moderate (45%), and high (25%). Significant associations were found between antibody incidence and age (P = 0.015), sex (P = 0.032), and season (P = 0.021). Specifically, the antibody prevalence was greater in the older age groups, with the highest prevalence observed in the 51–65 years’ group (87%), compared with 82% in the 31–50 years’ group and 65% in the 18–30 years’ group. In terms of sex, females had a slightly greater prevalence (80%) than males did (76%). In addition, the antibody prevalence was greater during the rainy season (85%) than during the dry season (71%).

Conclusions:
This study revealed a significant seroprevalence of Plasmodium spp. antibodies in Etsako, despite low mosquito prevalence. These findings underscore the persistence of past immunity despite reduced transmission rates. It is important to explore additional factors that may influence the antibody test results, as some variables were not included in this research. Tailored malaria control strategies considering local immunity dynamics are crucial for sustaining progress in malaria elimination efforts in similar settings.