Risk factors for schistosomiasis in an urban area in northern Côte d'Ivoire

Abstract

Background: Schistosomiasis is a water-based disease transmitted by trematodes belonging to the genus Schistosoma. The aim of this study was to assess the relationship between the prevalence of schistosomiasis and access to water, sanitation and hygiene (WASH) and environmental and socioeconomic factors in the city of Korhogo, northern Côte d'Ivoire.

Methods: A cross-sectional study including 728 randomly selected households was conducted in Korhogo in March 2015. The heads of the households were interviewed about access to WASH and environmental and socioeconomic factors. All children abed between 5 and 15 years living in the households were selected to provide stool and urine samples for parasitological diagnosis of Schistosoma mansoni and Schistosoma haematobium infection. The relationship between infection with S. mansoni and potential risk factors was analysed by a mixed logistic regression model with 'household' as a random factor. Likelihood ratio tests were used to identify factors that were significantly associated with a Schistosoma spp. infection.

Results: The overall prevalence of schistosomiasis among school-aged children in Korhogo was 1.9% (45/2341) composed of 0.3% (3/1248) S. haematobium and 3.5% (42/1202) S. mansoni. Due to the low prevalence of S. haematobium infection, risk factor analysis was limited to S. mansoni. Boys were 7.8 times more likely to be infected with S. mansoni than girls. Children between 10 and 15 years of age were 3.8 times more likely to be infected than their younger counterparts aged 5-10 years. Moreover, living in a house further away from a water access point (odds ratio [OR] = 0.29, 95% confidence interval [CI]: 0.13-0.70) and abstaining from swimming in open freshwater bodies (OR = 0.16, 95% CI: 0.04-0.56) were significantly associated with decreased odds of S. mansoni infection. The socioeconomic status did not appear to influence the prevalence of S. mansoni.

Conclusions: A strategy to reduce the incidence of schistosomiasis should focus on health education to change the behaviour of populations at risk and encourage communities to improve sanitation and infrastructure in order to reduce contact with surface water.

Keywords: Côte d’Ivoire; Schistosomiasis; School-aged children; Urban agriculture; Vulnerability index; Water, Sanitation and Hygiene (WASH).

Fig. 1

Geographical distribution and type of drinking water sources in the households of Korhogo, stratified by neighbourhood (March 2015)

Fig. 2

Geographical distribution and type of latrines used in the households of Korhogo, stratified by neighbourhood (March 2015)

Fig. 3

Number of human-water contact sites and main activities at these sites in Korhogo, stratified by neighbourhood (March 2015)

Fig. 4

Principal component analysis of variables related to environmental vulnerability in the city of Korhogo (March 2015) in the F1-F2 plane. The x- and y-coordinates of a variable are given by its correlations with the first (F1) and second factor (F2), respectively

Fig. 5

Mean values of the first (x-coordinate) and second (y-coordinate) principal component score by neighbourhood. The mean value of the first score expresses environmental vulnerability of the respective neighbourhood (low values indicate higher vulnerability). Red lines indicate boundaries between consecutive categories of environmental vulnerability (defined by the k-means procedure)

Fig. 6

Spatial distribution of households with schistosomiasis cases in Korhogo (March 2015)