Epidemiological dynamics and associated risk factors of S. haematobium in humans and its snail vectors in Nigeria: a meta-analysis (1983-2018)

Urinary Schistosomiasis and Associated Risk Factors Among Primary School Students in the Zaki Local Government Area, Bauchi State, Nigeria

Urinary schistosomiasis, a water-based disease, is endemic to Nigeria. The infection is transmitted by trematodes known as Schistosoma haematobium. The goal of this study was to determine the occurrence of urinary schistosomiasis among primary school children in the Zaki Local Government Area, Bauchi State, Nigeria. A cross-sectional study involving 300 school pupils from three primary schools in Zaki was conducted between June and November of 2021. The urine samples were examined with the sedimentation technique to detect S. haematobium eggs. Data on socio-demographic characteristics and risk factors were obtained through a well-structured questionnaire. In SPSS version 24, the associations between the dependent and independent variables were evaluated with Chi-square, bivariate, and multiple logistic regression analyses. The strength of associations was determined with the odds ratio (OR) and 95% confidence interval. Urinary schistosomiasis was found in 29.7% of school-aged children in the three primary schools. Significantly higher prevalence was observed in the Almajiri (informal) school (59.6%) and one public primary school (31.5%), P = 0.001. Boys were four times more likely than girls to have schistosomiasis [AOR (95% CI): 4.38 (2.23–8.60)]. Children who played in shallow water had a higher risk of contracting schistosomiasis infection and were five times more likely to be infected [AOR (95% CI): 5.14 (1.97–13.37)]. Children who had blood in their urine (hematuria) were nearly nine times more likely to be infected [AOR (95% CI): 9.64 (4.79–20.66)]. The present study indicated that urinary schistosomiasis is endemic to the study area in the Zaki Local Government Area, with a moderate infection rate.

A cross-sectional survey of the knowledge, attitudes and practices regarding schistosomiasis among rural schoolchildren in Taiz governorate, southwestern Yemen

BACKGROUND

This cross-sectional survey aimed to assess the knowledge, attitudes and practices (KAP) towards schistosomiasis among rural schoolchildren in Taiz governorate, southwestern Yemen.

METHODS

A total of 406 children were screened for urogenital and intestinal schistosomiasis. A pretested questionnaire was used to collect the children's demographic and socio-economic information and their KAP towards schistosomiasis.

RESULTS

Overall, 73 children (18%) were found to be infected by Schistosoma mansoni. None of the children were positive for Schistosoma haematobium. The prevalence of intestinal schistosomiasis was significantly higher among boys than girls (22.1% vs 12%; p=0.010). Approximately two-thirds (63.3% [257/406]) of the children had heard about schistosomiasis, however, only 38.5%, 53.6%, 28.4% and 38.1% had correct knowledge concerning the causes, symptoms, transmission and prevention, respectively. A significantly higher level of knowledge was observed among boys and Schistosoma-infected children compared with girls and non-infected children (p<0.05). However, a better level of knowledge does not seem to translate directly into the performance of hygienic practices. Multivariate logistic regression showed that sex and infection status were the significant predictors of good knowledge.

CONCLUSIONS

Intestinal schistosomiasis is prevalent among schoolchildren in rural Yemen. The findings reveal that children's knowledge about schistosomiasis is inadequate. Therefore, besides mass drug administration, integrated control programmes should also include health education and the provision of improved drinking water and proper sanitation.

Prevalence of Schistosoma mansoni and S. haematobium in Snail Intermediate Hosts in Africa: A Systematic Review and Meta-analysis

Background

Schistosomiasis is caused by Schistosoma mansoni and S. haematobium in Africa. These schistosome parasites use freshwater snail intermediate hosts to complete their lifecycle. Varied prevalence rates of these parasites in the snail intermediate hosts were reported from several African countries, but there were no summarized data for policymakers. Therefore, this study was aimed to systematically summarize the prevalence and geographical distribution of S. mansoni and S. haematobium among freshwater snails in Africa.

Methods

Literature search was carried out from PubMed, Science Direct, and Scopus which reported the prevalence of S. mansoni and S. haematobium among freshwater snails in Africa. The pooled prevalence was determined using a random-effect model, while heterogeneities between studies were evaluated by I² test. The meta-analyses were conducted using Stata software, metan command.

Results

A total of 273,643 snails were examined for the presence of S. mansoni and S. haematobium cercaria in the eligible studies. The pooled prevalence of schistosome cercaria among freshwater snails was 5.5% (95% CI: 4.9–6.1%). The pooled prevalence of S. mansoni and S. haematobium cercaria was 5.6% (95% CI: 4.9–6.3%) and 5.2% (95% CI: 4.6–5.7%), respectively. The highest pooled prevalence was observed from Nigeria (19.0%; 95% CI: 12.7–25.3%), while the lowest prevalence was reported from Chad (0.05%; 95% CI: 0.03–0.13). Higher prevalence of schistosome cercaria was observed from Bulinus globosus (12.3%; 95% CI: 6.2–18.3%) followed by Biomphalaria sudanica (6.7%; 95% CI: 4.5–9.0%) and Biomphalaria pfeifferi (5.1%; 95% CI: 4.1–6.2%). The pooled prevalence of schistosome cercaria obtained using PCR was 26.7% in contrast to 4.5% obtained by shedding cercariae.

Conclusion

This study revealed that nearly 6% of freshwater snails in Africa were infected by either S. haematobium or S. mansoni. The high prevalence of schistosomes among freshwater snails highlights the importance of appropriate snail control strategies in Africa.