Detection of Galba truncatula, Fasciola hepatica and Calicophoron daubneyi environmental DNA within water sources on pasture land, a future tool for fluke control?

Rhys Aled Jones,Teri E Davies,Chelsea N Davis,Pauline Rees Stevens,Peter M Brophy,Hefin Wyn Williams,Holly Emberson

doi:10.1186/s13071-018-2928-z

Rhys Aled Jones, Teri E Davies + Show 5 more

Open Access

https://doi.org/10.1186/s13071-018-2928-z

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Abstract

BackgroundIncreasing trematode prevalence and disease occurrence in livestock is a major concern. With the global spread of anthelmintic resistant trematodes, future control strategies must incorporate approaches focusing on avoidance of infection. The reliance of trematodes on intermediate snail hosts to successfully complete their life-cycle means livestock infections are linked to the availability of respective snail populations. By identifying intermediate snail host habitats, infection risk models may be strengthened whilst farmers may confidently apply pasture management strategies to disrupt the trematode life-cycle. However, accurately identifying and mapping these risk areas is challenging.MethodsIn this study, environmental DNA (eDNA) assays were designed to reveal Galba truncatula, Fasciola hepatica and Calicophoron daubneyi presence within water sources on pasture land. eDNA was captured using a filter-based protocol, with DNA extracted using the DNeasy® PowerSoil® kit and amplified via PCR. In total, 19 potential G. truncatula habitats were analysed on four farms grazed by livestock infected with both F. hepatica and C. daubneyi.ResultsGalba truncatula eDNA was identified in 10/10 habitats where the snail was detected by eye. Galba truncatula eDNA was also identified in four further habitats where the snail was not physically detected. Fasciola hepatica and C. daubneyi eDNA was also identified in 5/19 and 8/19 habitats, respectively.ConclusionsThis study demonstrated that eDNA assays have the capabilities of detecting G. truncatula, F. hepatica and C. daubneyi DNA in the environment. Further assay development will be required for a field test capable of identifying and quantifying F. hepatica and C. daubneyi infection risk areas, to support future control strategies. An eDNA test would also be a powerful new tool for epidemiological investigations of parasite infections on farms.

Highlights

Increasing trematode prevalence and disease occurrence in livestock is a major concern
Detectable G. truncatula and C. daubneyi DNA was shown to flow through 2.7 μm pore sized glass microfiber filter, in each instance where DNA was amplified from 0.7 μm pore sized filters, environmental DNA (eDNA) was amplified from the 2.7 μm pore sized filters
This paper demonstrates that eDNA assays have the capability of detecting G. truncatula, F. hepatica and C. daubneyi eDNA in water collected from pasture land

Summary

Introduction

Increasing trematode prevalence and disease occurrence in livestock is a major concern. Future control for trematodes should incorporate strategies focusing on avoidance of infection [7, 8] As both F. hepatica and C. daubneyi are reliant on the same intermediate snail host, Galba truncatula [9], infection risk areas for these parasites will be limited to pastures harbouring these snails. Galba truncatula snails are highly dependent on wet climatic and environmental conditions [10], and their presence and densities will vary within fields and specific fluke infection risk areas will be present on farms [11] Identifying these risk areas will strengthen trematode infection risk models [12], and support farmers to implement farm management practices such as drainage, rotational grazing and fencing and thereby reduce contact between vulnerable animals and the infective metacercariae. Fluke infection risk areas must first be accurately identified to maximise the cost-benefit of these often expensive practises

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