Genetic Diversity within Schistosoma haematobium: DNA Barcoding Reveals Two Distinct Groups

Webster, Bonnie L.; Emery, Aidan M.; Webster, Joanne P.; Gouvras, Anouk N.; Garba, Amadou; Diaw, O. T.; Seye, Mohmoudane M.; Tchuenté, L. A. Tchuem; Simoonga, Christopher; Mwanga, Joseph R.; Lange, Charles N.; Kariuki, Curtis; Mohammed, Khalfan A.; Stothard, J. Russell; Rollinson, David

doi:10.1371/journal.pntd.0001882

Cited by 56 publications

(104 citation statements)

References 39 publications

(69 reference statements)

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“…A similar observation was made in lifelong residents and residential newcomers in Kenya [37]. It might also be that as S. haematobium species are more genetically diverse in Zanzibar than in mainland Africa [38], immigrants might be exposed to S. haematobium genotypes to which they are more susceptible. Noteworthy, a study on the neighboring Mafia Island found that all children with a S. haematobium infection reported a travel history to mainland Tanzania [39].…”

Section: Discussionsupporting

confidence: 62%

Elimination of Schistosomiasis Transmission in Zanzibar: Baseline Findings before the Onset of a Randomized Intervention Trial

Knopp

Person²,

Shaali

et al. 2013

PLoS Negl Trop Dis

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BackgroundGaining and sustaining control of schistosomiasis and, whenever feasible, achieving local elimination are the year 2020 targets set by the World Health Organization. In Zanzibar, various institutions and stakeholders have joined forces to eliminate urogenital schistosomiasis within 5 years. We report baseline findings before the onset of a randomized intervention trial designed to assess the differential impact of community-based praziquantel administration, snail control, and behavior change interventions.MethodologyIn early 2012, a baseline parasitological survey was conducted in ∼20,000 people from 90 communities in Unguja and Pemba. Risk factors for schistosomiasis were assessed by administering a questionnaire to adults. In selected communities, local knowledge about schistosomiasis transmission and prevention was determined in focus group discussions and in-depths interviews. Intermediate host snails were collected and examined for shedding of cercariae.Principal FindingsThe baseline Schistosoma haematobium prevalence in school children and adults was 4.3% (range: 0–19.7%) and 2.7% (range: 0–26.5%) in Unguja, and 8.9% (range: 0–31.8%) and 5.5% (range: 0–23.4%) in Pemba, respectively. Heavy infections were detected in 15.1% and 35.6% of the positive school children in Unguja and Pemba, respectively. Males were at higher risk than females (odds ratio (OR): 1.45; 95% confidence interval (CI): 1.03–2.03). Decreasing adult age (OR: 1.04; CI: 1.02–1.06), being born in Pemba (OR: 1.48; CI: 1.02–2.13) or Tanzania (OR: 2.36; CI: 1.16–4.78), and use of freshwater (OR: 2.15; CI: 1.53–3.03) showed higher odds of infection. Community knowledge about schistosomiasis was low. Only few infected Bulinus snails were found.Conclusions/SignificanceThe relatively low S. haematobium prevalence in Zanzibar is a promising starting point for elimination. However, there is a need to improve community knowledge about disease transmission and prevention. Control measures tailored to the local context, placing particular attention to hot-spot areas, high-risk groups, and individuals, will be necessary if elimination is to be achieved.

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Section: Discussionsupporting

confidence: 62%

Elimination of Schistosomiasis Transmission in Zanzibar: Baseline Findings before the Onset of a Randomized Intervention Trial

Knopp

Person²,

Shaali

et al. 2013

PLoS Negl Trop Dis

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“…identified as either S. bovis or S. haematobium by the three interspecific single nucleotide polymorphisms (Webster et al, 2012).…”

Section: Resultsmentioning

confidence: 99%

Occurrence ofSchistosoma bovison Pemba Island, Zanzibar: implications for urogenital schistosomiasis transmission monitoring

et al. 2018

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The causative agent of urogenital schistosomiasis, Schistosoma haematobium, was thought to be the only schistosome species transmitted through Bulinus snails on Unguja and Pemba Island (Zanzibar, United Republic of Tanzania). For insights into the environmental risk of S. haematobium transmission on Pemba Island, malacological surveys collecting Bulinus globosus and B. nasutus, two closely related potential intermediate hosts of S. haematobium were conducted across the island in November 2016. Of 1317 B. globosus/B. nasutus collected, seven B. globosus, identified through sequencing a DNA region of the mitochondrial cytochrome oxidase subunit 1 (cox1), were observed with patent infections assumed to be S. haematobium. However, when the collected cercariae were identified through sequencing a region of the cox1 and the nuclear internal transcribed spacer (ITS1 + 2), schistosomes from five of these B. globosus collected from a single locality were in fact S. bovis. The identified presence of S. bovis raises concerns for animal health on Pemba, and complicates future transmission monitoring of S. haematobium. These results show the pertinence for not only sensitive, but also species-specific markers to be used when identifying cercariae during transmission monitoring, and also provide the first molecular confirmation for B. globosus transmitting S. bovis in East Africa.

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“…DNA barcoding studies not only propose their utility in discovering species in wide-ranging taxa (Johnsen et al 2010;Nijman & Aliabadian 2013) but also point to their biogeographic and phylogeographic utility (Carr et al 2011;Nwani et al 2011;Webster et al 2012;Ashfaq et al 2014). Theory predicts increased variation in genetic distance over increased geographical scale (Wright 1943;Nekola & White 1999), and empirical studies confirm such intraspecific trends (Avise 2000).…”

Section: Introductionmentioning

confidence: 99%

DNA barcoding gap: reliable species identification over morphological and geographical scales

Čandek

Kuntner

2014

Molecular Ecology Resources

167

119

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The philosophical basis and utility of DNA barcoding have been a subject of numerous debates. While most literature embraces it, some studies continue to question its use in dipterans, butterflies and marine gastropods. Here, we explore the utility of DNA barcoding in identifying spider species that vary in taxonomic affiliation, morphological diagnosibility and geographic distribution. Our first test searched for a 'barcoding gap' by comparing intra- and interspecific means, medians and overlap in more than 75,000 computed Kimura 2-parameter (K2P) genetic distances in three families. Our second test compared K2P distances of congeneric species with high vs. low morphological distinctness in 20 genera of 11 families. Our third test explored the effect of enlarging geographical sampling area at a continental scale on genetic variability in DNA barcodes within 20 species of nine families. Our results generally point towards a high utility of DNA barcodes in identifying spider species. However, the size of the barcoding gap strongly depends on taxonomic groups and practices. It is becoming critical to define the barcoding gap statistically more consistently and to document its variation over taxonomic scales. Our results support models of independent patterns of morphological and molecular evolution by showing that DNA barcodes are effective in species identification regardless of their morphological diagnosibility. We also show that DNA barcodes represent an effective tool for identifying spider species over geographic scales, yet their variation contains useful biogeographic information.

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Genetic Diversity within Schistosoma haematobium: DNA Barcoding Reveals Two Distinct Groups

Cited by 56 publications

References 39 publications

Elimination of Schistosomiasis Transmission in Zanzibar: Baseline Findings before the Onset of a Randomized Intervention Trial

Elimination of Schistosomiasis Transmission in Zanzibar: Baseline Findings before the Onset of a Randomized Intervention Trial

Occurrence ofSchistosoma bovison Pemba Island, Zanzibar: implications for urogenital schistosomiasis transmission monitoring

DNA barcoding gap: reliable species identification over morphological and geographical scales

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