Mapping and prediction of schistosomiasis in Nigeria using compiled survey data and Bayesian geospatial modelling

Abstract

Abstract. Schistosomiasis prevalence data for Nigeria were extracted from peer-reviewed journals and reports, geo-referenced and collated in a nationwide geographical information system database for the generation of point prevalence maps. This exercise revealed that the disease is endemic in 35 of the country's 36 states, including the federal capital territory of Abuja, and found in 462 unique locations out of 833 different survey locations. Schistosoma haematobium, the predominant species in Nigeria, was found in 368 locations (79.8%) covering 31 states, S. mansoni in 78 (16.7%) locations in 22 states and S. intercalatum in 17 (3.7%) locations in two states. S. haematobium and S. mansoni were found to be co-endemic in 22 states, while co-occurrence of all three species was only seen in one state (Rivers). The average prevalence for each species at each survey location varied between 0.5% and 100% for S. haematobium, 0.2% to 87% for S. mansoni and 1% to 10% for S. intercalatum. The estimated prevalence of S. haematobium, based on Bayesian geospatial predictive modelling with a set of bioclimatic variables, ranged from 0.2% to 75% with a mean prevalence of 23% for the country as a whole (95% confidence interval (CI): 22.8-23.1%). The model suggests that the mean temperature, annual precipitation and soil acidity significantly influence the spatial distribution. Prevalence estimates, adjusted for school-aged children in 2010, showed that the prevalence is <10% in most states with a few reaching as high as 50%. It was estimated that 11.3 million children require praziquantel annually (95% CI: 10.3-12.2 million).

Prevalence, intensity and spatial co-distribution of schistosomiasis and soil transmitted helminths infections in Ogun state, Nigeria

“…Here, we present for the first time the co-spatial distribution maps of schistosomiasis and STHs at LGA (implementation unit) for Ogun State to support integrated control like other studies in Kenya, Uganda, Cameroon and Zimbabwe (Handzel et al 2003;Kabatereine et al 2012;Tchuem Tchuente et al 2013). The prevalence and intensities of both diseases point out the fact that Schistosomiasis/STH infection remains a major public health problem in Ogun State (Ekpo et al 2012(Ekpo et al , 2013Oluwole et al 2015). Schistosomiasis is a focal disease, prevalent in areas where there are high human-water contact practices with water bodies such as dams, rivers or irrigation canals, poor sanitation and poor access to potable water (Ekpo et al 2013) Schistosoma haematobium was the most widely distributed and most prevalent among the two species of Schistosoma found in this study.…”

Female genital schistosomiasis (FGS) in Ogun State, Nigeria: a pilot survey on genital symptoms and clinical findings

“…Around certain transmission foci in Ogun State, for example, local prevalence can very high ∼90% (Akinwale et al 2010) as water contact activities among the rural populace, albeit recreational and or domestic, are particularly common. These typically include: bathing, swimming, drinking, washing clothes or kitchen utensils and fetching of water, such that each activity serves as an oftendaily pathway for acquiring infections (Ekpo et al 2008(Ekpo et al , 2010(Ekpo et al , 2013Sam-Wobo et al 2009;Oladoyin et al 2015).…”

Modeling the risk of transmission of schistosomiasis in Akure North Local Government Area of Ondo State, Nigeria using satellite derived environmental data

“…S . haematobium is the predominant specie in the country corresponding to 79.8% of all reported cases [5]. It often exceeds the high-endemicity threshold of 50% prevalence.…”