Transmission and diversity of Schistosoma haematobium and S. bovis and their freshwater intermediate snail hosts Bulinus globosus and B. nasutus in the Zanzibar Archipelago, United Republic of Tanzania

Pennance, Tom; Makame, Shaali; Amour, Amour Khamis; Suleiman, Khamis Rashid; Muhsin, Mtumweni Ali; Kabole, Fatma; Ali, Said M.; Archer, John; Allan, Fiona; Emery, Aidan; Rabone, Muriel; Knopp, Stefanie; Rollinson, David; Cable, Joanne; Webster, Bonnie L.

doi:10.1371/journal.pntd.0010585

“…A more detailed understanding of the underlying systematics for B. globosus and B. productus is important because both are vectors of S. haematobium and have been implicated in natural infections by this study and by others [59,60,[91][92][93] in the LVB. These taxonomic difficulties are especially unfortunate for the B. globosus species complex, members of which are important hosts for S. haematobium across tropical Africa; it remains awkward as to how to accurately name these important vector snails.…”

Section: Plos Neglected Tropical Diseasesmentioning

confidence: 89%

Bulinus snails in the Lake Victoria Basin in Kenya: Systematics and their role as hosts for schistosomes

Babbitt

¹

,

Laidemitt

²

,

Mutuku

³

et al. 2023

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The planorbid gastropod genus Bulinus consists of 38 species that vary in their ability to vector Schistosoma haematobium (the causative agent of human urogenital schistosomiasis), other Schistosoma species, and non-schistosome trematodes. Relying on sequence-based identifications of bulinids (partial cox1 and 16S) and Schistosoma (cox1 and ITS), we examined Bulinus species in the Lake Victoria Basin in Kenya for naturally acquired infections with Schistosoma species. We collected 6,133 bulinids from 11 sites between 2014–2021, 226 (3.7%) of which harbored Schistosoma infections. We found 4 Bulinus taxa from Lake Victoria (B. truncatus, B. tropicus, B. ugandae, and B. cf. transversalis), and an additional 4 from other habitats (B. globosus, B. productus, B. forskalii, and B. scalaris). S. haematobium infections were found in B. globosus and B. productus (with infections in the former predominating) whereas S. bovis infections were identified in B. globosus, B. productus, B. forskalii, and B. ugandae. No nuclear/mitochondrial discordance potentially indicative of S. haematobium/S. bovis hybridization was detected. We highlight the presence of Bulinus ugandae as a distinct lake-dwelling taxon closely related to B. globosus yet, unlike all other members of the B. africanus species group, is likely not a vector for S. haematobium, though it does exhibit susceptibility to S. bovis. Other lake-dwelling bulinids also lacked S. haematobium infections, supporting the possibility that they all lack compatibility with local S. haematobium, thereby preventing widespread transmission of urogenital schistosomiasis in the lake’s waters. We support B. productus as a distinct species from B. nasutus, B. scalaris as distinct from B. forskalii, and add further evidence for a B. globosus species complex with three lineages represented in Kenya alone. This study serves as an essential prelude for investigating why these patterns in compatibility exist and whether the underlying biological mechanisms may be exploited for the purpose of limiting schistosome transmission.

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“…productus is important because both hosts are vectors of S. haematobium and have been implicated in natural infections by this study and by others [59, 60,[82][83][84] in the LVB. These .…”

Section: B Nasutus Has Traditionally Been Divided Into Two Subspecies...mentioning

confidence: 60%

“…A more detailed understanding of the underlying systematics for B. globosus and B. productus is important because both hosts are vectors of S. haematobium and have been implicated in natural infections by this study and by others [59,60,82–84] in the LVB. These taxonomic difficulties are especially unfortunate for the B. globosus species complex, members of which are important hosts for S. haematobium across tropical Africa; it remains awkward as to how to accurately name these important vector snails.…”

Section: Discussionmentioning

confidence: 84%

Bulinus snails in the Lake Victoria Basin in Kenya: systematics and their role as hosts for schistosomes

Babbitt

¹

,

Laidemitt

²

,

Mutuku

³

et al. 2022

Preprint

0

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The planorbid gastropod genus Bulinus consists of 38 species that vary in their ability to vector Schistosoma haematobium (the causative agent of human urogenital schistosomiasis), other Schistosoma species, and non-schistosome trematodes infecting animals. Relying on sequence-based identifications of bulinids (partial cox1 and 16S) and Schistosoma (cox1 and ITS), we examined Bulinus species in the Lake Victoria Basin in Kenya for naturally acquired infections with Schistosoma species. We collected 6,133 bulinids from 11 sites between 2014-2021, 226 (3.7%) of which harbored Schistosoma infections. We found 4 Bulinus taxa from Lake Victoria (B. truncatus, B. tropicus, B. ugandae, and B. cf. transversalis), and an additional 4 from other habitats (B. globosus, B. productus, B. forskalii, and B. scalaris). S. haematobium infections were found in B. globosus and B. productus (with infections in the former predominating) whereas S. bovis infections were identified in B. globosus, B. productus, B. forskalii, and B. ugandae. No nuclear/mitochondrial discordance potentially indicative of S. haematobium/S. bovis hybridization was detected. We highlight the presence of Bulinus ugandae as a distinct lake-dwelling taxon closely related to B. globosus yet, unlike all other members of the B. africanus species group, is likely not a vector for S. haematobium, though it does exhibit susceptibility to S. bovis. Other lake-dwelling bulinids also lacked S. haematobium infections, supporting the possibility that they all lack compatibility with local S. haematobium, thereby preventing widespread transmission of urogenital schistosomiasis in the lake’s waters. We support B. productus as a distinct species from B. nasutus, B. scalaris as distinct from B. forskalii, and add further evidence for a B. globosus species complex with three lineages represented in Kenya alone. This study serves as an essential prelude for investigating why these patterns exist and whether the underlying biological mechanisms may be exploited for the purpose of limiting schistosome transmission.Author SummarySchistosomiasis is a neglected tropical disease caused by members of the genus Schistosoma. Every schistosome species is dependent on a particular species, or array of species, of intermediate snail host(s) for transmission. In the Lake Victoria Basin in Kenya, two related schistosome species (Schistosoma haematobium and Schistosoma bovis) utilize multiple species within the genus Bulinus as intermediate hosts. Discerning which bulinid species vector the agent of human schistosomiasis, which are vectors for bovine schistosomiasis, which are vectors for both, and identifying the habitats for each, is critical to understanding local transmission patterns. Confident snail species identification is a prerequisite for implicating a snail in transmission. Certain closely related bulinids cannot be confidently distinguished between using morphological criteria and previously published misidentifications have obscured the literature regarding where human schistosomiasis transmission occurs. This study used sequence-based methods to identify local bulinid species and to identify schistosomes from infected snails. Our results implicate two bulinid species in the transmission of S. haematobium and four species in the transmission of S. bovis. Both S. haematobium associated species were found exclusively in streams and dams in the Lake Victoria Basin thereby seemingly keeping the shores of Lake Victoria free of S. haematobium transmission.

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“…• Buruli ulcer • Chagas disease The NTDs are mainly diseases in developing countries, as shown in the maps of some of the NTDs down if compared to the map of poverty shown earlier in the chapter (Figure 6) [77][78][79][80][81][82][83][84]. However, due to a lack of funding, the WHO published a 2021 booklet as a road to end the NTDs by 2030 by integrating their prevention and control (Figure 7) [76].…”

Section: Neglected Tropical Diseases Related To Povertymentioning

confidence: 99%

Impact of Poverty on Health

Alqassim¹

2023

Healthcare Access - New Threats, New Approaches

0

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Poverty is not merely the absence of money but the absence of resources to get the necessities of life. Poverty and health are always in a reciprocal relationship. This relation came to light in 1948 when the WHO defined health as complete physical, mental and social wellbeing. In 1987, the Alma-Ata declaration opened the discussion on health inequity. This opened the door for thousands of projects, proposals, and publications on this relation. Although the relationship between poverty and infectious diseases was clear, there was inequity in funding. The Global Fund invests US$ 4 billion annually for AIDS, tuberculosis, and Malaria, while other diseases lack funds. That is why they were considered neglected tropical diseases. However, the relationship between health and poverty is not limited to infectious diseases but includes noninfectious problems like malnutrition and injuries. In this chapter, we will assess the association between poverty as a predictor and health as an outcome.

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Transmission and diversity of Schistosoma haematobium and S. bovis and their freshwater intermediate snail hosts Bulinus globosus and B. nasutus in the Zanzibar Archipelago, United Republic of Tanzania

Cited by 11 publications

References 62 publications

Bulinus snails in the Lake Victoria Basin in Kenya: Systematics and their role as hosts for schistosomes

Bulinus snails in the Lake Victoria Basin in Kenya: Systematics and their role as hosts for schistosomes

Bulinus snails in the Lake Victoria Basin in Kenya: systematics and their role as hosts for schistosomes

Impact of Poverty on Health

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