Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Review
. 2020 Sep 7:2020:8850840.
doi: 10.1155/2020/8850840. eCollection 2020.

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

Tamirat Hailegebriel  1 , Endalkachew Nibret  1 , Abaineh Munshea  1
Affiliations
Review

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

Tamirat Hailegebriel et al. J Trop Med. .

Abstract

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 I 2 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.

PubMed Disclaimer

Conflict of interest statement

The authors declare that there are no conflicts of interest.

Figures

Figure 1
Figure 1
PRISMA flow diagram of for the inclusion of studies on the prevalence of S. mansoni and S. haematobium in freshwater snails in Africa.
Figure 2
Figure 2
Forest plot diagram showing the prevalence of human infecting schistosomes (S. mansoni and S. haematobium) examined in snails in Africa. Each square represent effect size (ES) of individual studies, and the horizontal line represents the 95% CI. The diamond indicates the pooled effect and the vertical dash lines indicate the overall estimate.
Figure 3
Figure 3
Geographical distribution and pooled prevalence of S. mansoni and S. haematobium among Biomphalaria and Bulinus snails, respectively, in African countries.
Figure 4
Figure 4
The pooled prevalence of schistosome cercaria among freshwater snails in Africa based on year of publication.
Figure 5
Figure 5
Forest plot diagram showing the estimated effect size of S. mansoni in Biomphalaria snails and S. haematobium Bulinus snail in Africa.
Figure 6
Figure 6
Forest plot diagram showing the pooled prevalences of S. mansoni and S. haematobium among freshwater snails examined by cercarial shedding and PCR.
Figure 7
Figure 7
Funnel plot with 95% confidence limit showing publication bias across studies on the prevalence of S. mansoni and S. haematobium among freshwater snails of Africa.
See this image and copyright information in PMC

References

    1. WHO. Schistosomiasis. 2020. https://www.who.int/news-room/fact-sheets/detail/schistosomiasis.
    1. Barry M. A., Simon G. G., Mistry N. Global trends in neglected tropical disease control and elimination: impact on child health. Archives of Disease in Childhood. 2013;98(8):p. 635. doi: 10.1136/archdischild-2012-302338. - DOI - PubMed
    1. Hotez P., Keiser J., Bos R., Tanner M., Utzinger J. Schistosomiasis and water resources development: systematic review, meta-analysis, and estimates of people at risk. The Lancet Infectious Diseases. 2006;6(7):411–425. doi: 10.1016/s1473-3099(06)70521-7. - DOI - PubMed
    1. Inobaya M. T., Olveda R. M., Chau T. N., Olveda D. U., Ross A. G. Prevention and control of schistosomiasis: a current perspective. Research and Reports in Tropical Medicine. 2014;2014(5):65–75. - PMC - PubMed
    1. Colley D. G., Bustinduy A. L., Secor W. E., King C. H. Human schistosomiasis. The Lancet. 2014;383(9936):2253–2264. doi: 10.1016/s0140-6736(13)61949-2. - DOI - PMC - PubMed