Prevalence of urogenital and intestinal schistosomiasis among school children in South-west Nigeria

Background The risk of co-infection with Schistosoma haematobium and S. mansoni and the potential harmful effect on morbidity and control is enhanced by the overlapping distribution of both species in sub-Saharan Africa. Despite the reported high endemicity of both species in Nigeria, studies on the spread and effect of their mixed infection are limited. Therefore, a cross-sectional survey was conducted among school children in two communities in South-west Nigeria to investigate the prevalence of mixed human schistosome infection, intensity, and possible ectopic egg elimination. Methods Urine and stool samples were collected from consenting school children in Ilie and Ore communities of Osun State, Nigeria. Schistosoma haematobium eggs were detected in urine using the urine filtration technique, while S. mansoni eggs were detected in stool using the Kato–Katz thick smear technique. Results The study enrolled 466 primary and secondary school children (211; 45.3% males vs. 255; 54.7% females; mean age 11.6 ± 3.16 years). The overall prevalence of schistosomiasis was 40% (185/466), with 19% (89/466) recording single S. haematobium infection while 9% (41/465) had a single S. mansoni infection. The geometric mean egg count for S. haematobium was 189.4 egg/10ml urine; 95% CI: range 115.9–262.9, while for S. mansoni, it was 115.7 epg; 95% CI: range 78.4–152.9. The prevalence of ectopic S mansoni (S. mansoni eggs in urine) was 4.7%, while no ectopic S. haematobium (S. haematobium eggs in stool) was recorded. Mixed infection of S. haematobium/S. mansoni had a prevalence of 9.5% (44/466). More females (54.5%) presented with S. haematobium/S. mansoni co-infection. For both parasites, males had higher infection intensity, with a significant difference observed with S. haematobium (p = 0.0004). Hematuria was significant in individuals with single S. haematobium infection (p = 0.002), mixed ectopic S. haematobium/S. mansoni (p = 0.009) and mixed S. haematobium/S. mansoni/ectopic S. mansoni (p = 0.0003). Conclusions These findings suggest the probability of interspecific interactions between S. haematobium and S. mansoni. Scaling up of mass administration of praziquantel and control measures in the study areas is highly desirable.

the submission is accepted. Please make sure it is accurate.  Yes -all data are fully available without restriction Important countries with the highest disease burden [6]. The disease is caused by parasites of the genus 53 Schistosoma and is responsible for the most obvious reduction in age-standardized years lived 54 In this report, we present results from a cross-sectional study conducted to investigate possible 94 mixed Schistosoma infections and associated disease covariates in two schistosomiasis 95 endemic communities in Nigeria. 96 97

Study site 99
This study was conducted among school children (age 4-19 years), recruited from Ore and llie 100 communities, Osun State, Nigeria. Urine and stool samples were collected from the primary and 5 secondary school pupils in these communities, who consented or whose parents/guardian gave 102 consent to participate in this study. The two communities are located very closely on latitude 103

Sample Collection 112
The sample size was obtained, using the formula for a cross-sectional study [24]. Using a prior 113 prevalence of 37.5% among school children positive for schistosomiasis [23], a marginal error of 114 5% and a type 1 error of 5%, a minimum sample of 289 school children was needed. In all, 466 115 school children participated in this study. Individual demographic information was collected with 116 a structured questionnaire, while two sterile, universal containers, individually labelled for urine 117 and stool collection, were distributed to consenting school children. Instructions on proper urine 118 and stool collection procedure was given to the students; for each participant, one urine and 119 stool samples were collected. 120 121

Parasitological examination 122
The presence of the Sh egg was detected using the urine filtration technique, as previously 123   Table 2 with an overall prevalence of 31% and 187 10% for Sh and Sm, respectively. 188

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The association between ectopic Sm egg elimination and infection intensities of Sh and Sm is 190 shown in Table 3. High prevalence of ectopic Sm egg was observed in high infection intensities 191 of both Sh (18%) and Sm (15.6%) producing a strong significant association in both cases. 192 Figure 2 shows the relationship between age prevalence and infection intensity in the study 193 population. Age group 12-19 years recorded higher prevalence of Sh, Sm and ectopic Sm 194 infection compared to the younger age group (4-11 years), but the difference in all cases was 195 not statistically significant. In both Sh and Sm, the younger age group (4-11 years) had higher 196 infection intensity and was statistically significant (p=0.016) in the Sm group. For the ectopic Sm 197 infection group, the pattern was different as the older age group recorded the higher infection 198 intensity but the difference was not statistically significant ( Figure 2). 199

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The relationship between sex and infection intensity in the study population is shown in Figure  201 3. Females were more infected with both Sh and Sm, but the difference was not statistically 202 significant. On the other hand, male recorded more ectopic Sm infection but the difference was 203 not statistically significant. In both Sh and Sm, males had higher infection intensity and the 204 difference was significant in those infected with Sh (p=0.0004). In ectopic Sm, females had 205 higher infection intensity but the difference was not statistically significantly (Figure 3). The age-related prevalence of schistosomiasis has been shown to increase as the age 254 increases peaking in adolescence and lowering among adults [39]. Unfortunately, adults were 255 not included in this study making it impossible to investigate this age-infection profile. 256 Nevertheless, the adolescence group was significantly more infected, but had lower intensity of 257 infection compared to the younger age group in this study. The older children are engaged in 258 more water contact activity leading to the observed higher prevalent but possess longer history 259 of exposure and higher parasite-specific acquired immunity leading to lower infection intensity 260