Ethical approval for this study (FHST/EC/28) was obtained from the Ethical Committee, Faculty of Health Sciences and Technology, Ebonyi State University, Abakaliki (EBSU/2016/51032).

The participants of this cross-sectional study, conducted between July 2016 and December 2016, were selected by simple random sampling (with the aid of a Random Number Table) from amongst students of six primary schools in the Ikwo and Ohaukwu Local Government Areas (LGAs), following official authorisation by both Councils. Out of 348 pupils initially recruited from both LGAs (Ikwo, n = 186, Ohaukwu, n = 162), a total of 300 students, comprising 185 boys and 115 girls, aged between 5 and 15 years, participated in this study based on the inclusion requirements of written consent, completed questionnaire, and submission of urine specimens. A signed or thumb-printed written consent for voluntary participation of each student was obtained from a parent or guardian. Parents and guardians were informed that participants’ information would be treated with utmost confidentiality and used for the purpose of the research only before giving consent. They were also informed of the potential health and social benefits of the study. To protect the participants’ information, personal and quasi identifiers (such as occupation of the parents) were masked with numbers and letters, respectively. The sample size was determined using the formula described by Charan and Biswas¹⁸ for cross-sectional studies.

This study was carried out in Ohaukwu and Ikwo LGAs of Ebonyi State, south-east Nigeria. Ohaukwu LGA is located at latitude 6°31’58.3”N and longitude 8°1’22.9”E (central part) of Ebonyi State and has an area of about 517 km², with an estimated population of about 195 337, whereas Ikwo LGA is located at latitude 6°4’59”N and longitude 8°5’59”E (northern part) of Ebonyi State and has an area of about 500 km², with a population of about 214 969.¹⁹ The two LGAs are separated from each other by a distance of about 30 km.

This area has a typical tropical climate, comprising dry and wet seasons, with an annual average rainfall of 1300 mm and an atmospheric temperature of about 30 °C; the vegetation characteristics are predominantly guinea savannah. The area is made up of several rural communities traversed by streams and rivers, which constitute the inhabitants’ major source of water for domestic use, recreation and economic activities, particularly in the absence of pipe-borne water and other social amenities. It is mostly inhabited by peasant and subsistence farmers, whose activities have an important bearing on the ecology of the area. Rice farming, mainly in swampy terrains, is the major occupation in the area.

A questionnaire titled ‘Investigation of risk factors associated with the transmission of urinary schistiosomiasis in Ikwo and Ohaukwu Communities’ was administered verbally to each participant, parent, or guardian by the research assistants with the generous support of school tutors, who helped in communicating effectively in the local dialect. Participants’ information sought for in the questionnaire included age, residence, source(s) of water for domestic use, water contact activities, history of diseases with symptoms of haematuria, access to healthcare facilities, and the occupation and educational status of parents or guardian, amongst others.

Each participant was given a sterile dry plastic universal container with a screw lid, in which they were asked to take a terminal urine sample between 10:00 and 12:00, when the ova load is maximal.²⁰ Each container was labeled with the sex, age and number of the participant as provided in the questionnaire form. Fresh urine samples collected were examined macroscopically for presence of blood (haematuria). The samples were then preserved by adding 5 mL of dilute (0.3%) carbol-fuchsin solution to each 10 mL of urine,²¹ and transported to the laboratory in an ice-pack.

Categorical variables were used to assess the risks factors and prevalence of urinary schistosomiasis in this study. There were six categories, namely: LGA, sex, age, occupation, water sources, and water contact activities.

Microscopic examination of the urine samples for urinary schistosomiasis detection was based on detection of terminal-spine eggs of S. haematobium using a sedimentation concentration technique.¹⁸ Ten millilitres of each urine sample was collected from each sample container into a centrifuge tube and spun for 5 minutes at 3000 revolutions per minute to concentrate the eggs. Thereafter, the supernatant fluid was discarded into a Petri dish. A drop of the sediments was transferred to a clean and grease-free glass slide, covered with a coverslip and examined microscopically using x100 and x400 magnification for eggs of S. haematobium, recorded as eggs/10 mL of urine.

Cronbach’s alpha was used to verify the reliability of the data obtained in this study. The prevalence values were calculated by finding the percentage of the factors. Associations between demographic characteristics (age, sex, and occupation) and the prevalence of infection were analysed using Pearson’s chi-square test. Multivariate logistic regression analysis was used to evaluate the geographical and behavioural risks associated with S. haematobium infection. The geographical variables used in the analysis model included borehole, well, pond, stream and river water sources, whilst the behavioural variables comprised swimming, fishing, washing and other domestic uses. P-values of less than 0.05 were considered significant, and 95% confidence intervals were used to locate outliers.

Schistosoma haematobium infection was detected in 24 (8.0%) of the 300 students examined. The prevalence of infection was 10.0% (n = 150) in Ikwo LGA and 6.0% (n = 150) in Ohaukwu LGA. The difference between the prevalence of infection in Ohaukwu and Ikwo LGAs was not statistically significant (p = 0.24; Table 1).

The highest prevalence of infection by age was 9.4% (n = 160) amongst students aged 6–10 years. Students aged 11–15 years had a lower prevalence rate of 7.0% (n = 72), followed by those aged 1–5 years (n = 50; 6.0%), whereas students aged more than 15 years had the lowest (n = 18; 5.5%). The association between prevalence of infection and age of the participants was not statistically significant (p = 0.84; Table 2).

Of the 185 male students, 19 (10.3%) were infected with S. haematobium compared with 5 (4.3%) of the 115 female students. The impact of sex on the prevalence of infection was statistically significant (p = 0.038; Table 2).

The highest prevalence of infection by occupation (n = 128; 11.7%) was found amongst students whose parents or guardians were farmers, whilst children of public servants had the least (n = 61; 3.2%) (Table 2). A prevalence of 7.0% (n = 85) was found amongst children whose parents or guardians were traders, and 3.8% (n = 26) where the parents or guardians were fishermen. The relationship between the prevalence of infection and the occupation of parents was not statistically significant (p = 0.23; Table 2).

The highest rate of infection (n = 48; 25%) was found amongst students who utilised stream water mainly for domestic purposes. Infection rates of 14.0% (n = 50) were found amongst those that used pond water, 5.3% (n = 57) for river water, and 4.4% (n = 45) for well water. There was no case of infection amongst students who utilised water from borehole facilities; the odds of infection were about three times higher with participants who utilised freshwater sources within the locality compared with those who used borehole water, but this association was not statistically significant (p = 0.55; odds ratio = 2.77; 95% confidence interval: 7.23–22.77; Table 3).

A high infection rate of 10.5% (n = 95) was found amongst participants who engaged in swimming, compared with other activities that involved contact with freshwater sources (Table 4). Multivariate analysis showed a statistically significant association between participants’ water contact activities and the prevalence of infection (p = 0.007; odds ratio = 1.89; 95% confidence interval: 4.33–16.17).

Regardless of the age or sex of students, contact with freshwater sources was a crucial factor for disease transmission, based on the pattern of infection found in this study. The prevalence of the disease was particularly high amongst children who utilised stream water for domestic and other uses, compared with other sources of water, including ponds and river. No case of infection was found amongst students who had unlimited access to borehole water. This finding is consistent with the fact that S. haematobium infection occurs only where there is contact between the population and freshwater sources harbouring the snail vector as well as the infective stage of the parasite.³⁰ Thus, this study may have been considerably limited by an inability to examine the water sources for the snail host, and quantify the participants’ water contact activities. Nonetheless, a significant association was found between infection and students’ water contact activities. The zero-prevalence rate of the disease found amongst students who utilised borehole water facilities in this locality may underscore the development of infrastructure in rural communities as an important control approach for urinary schistosomiasis.

This study reports a low prevalence of 8.0% for urinary schistosomiasis amongst children in the study area, with a likelihood of further expansion in the disease rate and foci, if appropriate control measures are not initiated urgently by the local health authorities. Transmission of the disease in these communities is enhanced mainly by residents’ dependence on unsafe sources of water for domestic use, as well as behavioural and socio-economic tendencies that promote risky contacts with potentially parasite-infested water bodies. Continued disease surveillance and selective praziquantel chemotherapy for infected persons, health education of the residents for improved perception of the behavioural and socio-economic activities associated with the disease, and development of water sources would likely improve the living conditions of this rural population with a consequent reduction in the burden and transmission of the disease. Future studies on urinary schistosomiasis in these communities should include specific analysis of the water bodies, including malacological evaluation, as well as quantification of the water contact activities of the participants.