Systematic Review and Meta-Analysis on the Infection Rates of Schistosome Transmitting Snails in Southern Africa

Onyekachi Esther Nwoko; Chester Kalinda; Moses John Chimbari

doi:10.3390/tropicalmed7050072

Systematic Review and Meta-Analysis on the Infection Rates of Schistosome Transmitting Snails in Southern Africa

Trop Med Infect Dis. 2022 May 13;7(5):72. doi: 10.3390/tropicalmed7050072.

Authors

Onyekachi Esther Nwoko¹, Chester Kalinda^{1

2

3}, Moses John Chimbari^{1

4}

Affiliations

¹ Discipline of Public Health Medicine, School of Nursing and Public Health, College of Health Sciences, Howard Campus, University of KwaZulu-Natal, Durban 4000, South Africa.
² Bill and Joyce Cummings Institute of Global Health, University of Global Health Equity (UGHE), P.O. Box 6955, Kigali 20093, Rwanda.
³ Institute of Global Health Equity Research (IGHER), University of Global Health Equity (UGHE), P.O. Box 6955, Kigali 20093, Rwanda.
⁴ Department of Behavioural Science, Medical and Health Sciences, Great Zimbabwe University, Masvingo P.O. Box 1235, Zimbabwe.

Abstract

Efforts to interrupt and eliminate schistosomiasis as a public health problem have increased in several Southern African countries. A systematic review was carried out on the infection rates of snails that cause schistosomiasis in humans. The searches were conducted in PubMed, Web of Science, and Scopus databases, using the PRISMA guidelines from inception to 24 February 2022. The study quality was assessed by using the Joanna Briggs Institute prevalence critical appraisal checklist. Pooled infection rates were estimated by using an inverse variance heterogeneity model, while heterogeneity was determined by using Cochran's Q test and Higgins i² statistics. A total of 572 articles were screened, but only 28 studies were eligible for inclusion based on predetermined criteria. In the selected studies, 82,471 Bulinus spp. and 16,784 Biomphalaria spp. snails were screened for cercariae. The pooled infectivity of schistosome intermediate host snails, Biomphalaria spp., and Bulinus spp. were 1%, 2%, and 1%, respectively. Snail infection rates were higher in the 1900s compared to the 2000s. A Luis Furuya-Kanamori index of 3.16 indicated publication bias, and a high level of heterogeneity was observed. Although snail infectivity in Southern Africa is relatively low, it falls within the interval of common snail infection rates, thus indicating the need for suitable snail control programs that could interrupt transmission and achieve elimination.

Keywords: Biomphalaria spp.; Bulinus spp.; infection rates; intermediate host snails; schistosomiasis.

Publication types

Review

Grants and funding

This research was conducted as part of the Ph.D. work of the first author. This research was commissioned by the National Institute for Health Research (NIHR) Global Health Research program (16/136/33), UK and the University of KwaZulu-Natal through a Ph.D. studentship bursary awarded to Onyekachi Esther Nwoko by the College of Health Sciences. The views expressed in this publication are those of the author(s) and not necessarily those of the NIHR or the Department of Health and Social Care.