ArticleParasites & vectors2024
Impact of chemical snail control on intermediate host snail populations for urogenital schistosomiasis elimination in Pemba, Tanzania: findings of a 3-year intervention study.
Article in Parasites & vectors, 2024. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 5 papers.
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Who cites it
5 citing papers in PubMed.
- Effect of behavioral interventions on schistosomiasis-related knowledge, attitudes, and practices of schoolchildren in Pemba, Tanzania: A 4-year repeated cross-sectional study.PLoS neglected tropical diseases · 2025Trial
- An alien intermediate host snail,International journal for parasitology. Parasites and wildlife · 2026Article
- Evaluation of surveillance-response interventions for Schistosoma haematobium elimination on Pemba Island, Tanzania: A 4-year intervention study with repeated cross-sectional surveys.PLoS neglected tropical diseases · 2026Article
- Adaptive integrated intervention approaches for schistosomiasis elimination in Pemba: A 4-year intervention study and focus on hotspots.PLoS neglected tropical diseases · 2025Article
- Inverted Patterns of Schistosomiasis and Fascioliasis and Risk Factors Among Humans and Livestock in Northern Tanzania.Pathogens (Basel, Switzerland) · 2025Article
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10 authors.
Funding
Abstract
backgroundThe World Health Organization (WHO) has set the goal of eliminating schistosomiasis as a public health problem globally by 2030 and to interrupt transmission in selected areas. Chemical snail control is one important measure to reduce transmission and achieve local elimination. We aimed to assess the impact of several rounds of chemical snail control on the presence and number of the Schistosoma haematobium intermediate snail host (Bulinus spp.) in water bodies (WBs) on Pemba Island, Tanzania, a setting targeted for elimination of urogenital schistosomiasis.
methodsDuring the three annual intervention periods of the SchistoBreak study implemented in the north of Pemba from 2020 to 2024, malacological surveys were conducted up to four times per period in WBs of hotspot implementation units (IUs). Present freshwater snail species, vegetation, and WB characteristics were recorded. If Bulinus were found, the snails were inspected for Schistosoma infection and snail control with niclosamide was conducted.
resultsAcross the three intervention periods, a total of 112 WBs were identified in 8 hotspots IUs. The spatial distribution of WBs with Bulinus per IU was heterogeneous, ranging from 0.0% (0/15) of WBs infested in one IU in 2022 to 80.0% (8/10) of WBs infested in one IU in 2021. Bulinus presence was significantly associated with lower pH values in WBs (odds ratio: 0.2, 95% confidence interval 0.1-0.4). A total of 0.2% (6/2360) of collected Bulinus were shedding Schistosoma cercariae. Following snail control, the number of Bulinus decreased or remained absent in 56.7% (38/67) of visits at WBs when compared with the previous visit in 2021, 54.9% (28/51) in 2022, and 33.3% (32/96) in 2023. In a total of 43.1% (22/55) of initially infested WBs, no Bulinus were found in the survey round conducted a few weeks after the first application of niclosamide. However, 25.4% (14/55) of WBs showed a pattern of recurring Bulinus presence.
conclusionsThe distribution of WBs containing Bulinus was very heterogeneous. The percentage of Bulinus with patent Schistosoma infection in our study area was extremely low. Repeated niclosamide application reduced the number of Bulinus in WBs, but snails often recurred after one or multiple treatments. While chemical mollusciciding can reduce snail numbers, to fully break the S. haematobium transmission cycle, timely diagnosis and treatment of infected humans, access to clean water, sanitation, and health communication remain of prime importance.
trial registrationISRCTN, ISRCTN91431493. Registered 11 February. 2020, https://www.isrctn.com/ISRCTN91431493.
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