Climatic factors and spatial distribution of STHs in faecal samples collected from populations in Local Government Areas within Ibadan

Abstract

Background: The World Health Organization (WHO) aim to reduce the morbidity of Soil-Transmitted Helminth (STH) infection by 2025 in the tropical and sub-tropical regions of the world. The aim of this study is to determine the distribution patterns of STHs in the 11 Local Government Areas (LGAs) within Ibadan and investigate on the influence of climatic variations on the prevalence and intensity of STH infections in relation to risk parameters. Methods & Materials: A total of 1920 soil and 1320 faecal samples were collected between January 2017 and December 2018. Faecal samples were also collected from volunteer participants from each Local Government Area. Soil and faecal samples were examined for parasite prevalence, using parasitological techniques, while intensity was determined using parasitological approach. Climatic factors of the environment were determined using standard methods. A hand held Global Positioning System (GPS) device was used to obtain coordinates of sampled locations, the GPS data was converted to Easting and Northing points, and integrated to an image using Geographic Information System software (ArcGIS 9.3 software). Results: A total of 523 (39.6%) of collected samples contained parasites. Ascaris had the highest prevalence of 40.6%, followed by Trichuris (22.1%), Necator had 21.3%, Strongyloides had 9.4%, while Ancylostoma had 6.6%. No matter the amount of rainfall, STH prevalence is always high in the soil environment (OR = 0.03, p > 0.05) compare what we have for ambient temperature (OR = 0.08, p > 0.05) and relative humidity (OR = −0.09, p > 0.05). A regression analysis showed a negative sign between intensity and climatic factors. The spatial maps showed that Ona Ara LGA had between high and very high prevalence for Ascaris, Trichuris, Necator and Strongyloides species while the prevalence of Ancylostoma was low. The prevalence of STH in Ibadan North, Ibadan Northwest and Southwest was low for all the parasites compared to other LGAs. Conclusion: The overall prevalence of STH in the study area showed that infections is still high although below 50% and according to WHO guidelines, the population in the area should be given drugs ones a year.