Journal article
Diarrhoea associated with gastrointestinal parasites in grazing sheep
Veterinary Parasitology, Vol.282, Article 109139
2020
Abstract
Diarrhoea is a common, widespread and frustrating reality for sheep enterprises in most sheep producing regions globally and of particular concern in Australia as the major risk factor for breech flystrike. Parasitic disease has long been recognised as an important factor in diarrhoea in sheep, particularly the gastrointestinal nematodes (Trichostrongylus and Teladorsagia species). This review focuses on the role of parasitic infections in causing diarrhoea in sheep, with emphasis on the epidemiology of diarrhoea outbreaks related to worms and opportunities to manage the risk of diarrhoea outbreaks in sheep related to parasitic infections. Parasitic nematodes damage the gastrointestinal tract via a complex relationship between direct impacts from worms, such as physical changes to the gut mucosa, and indirect effects largely associated with the host response. Diarrhoea associated with large worm burdens is most efficiently managed through integrated parasite management programs. Despite some limitations, measuring faecal worm egg counts remains a mainstay for assessing the contribution of worms to outbreaks of diarrhoea in sheep. Larval hypersensitivity scouring is emerging as a significant cause of worm-related diarrhoea in sheep without large adult worm burdens in some geographic locations. The syndrome describes a heightened inflammatory response to the ingestion of trichostrongylid infective larvae seen in the gut of sheep with diarrhoea, and is most effectively addressed through selecting sheep for low breech soiling (‘dag scores’), as worm resistant sheep may show an increased propensity for diarrhoea, even with low rates of larval challenge. Importantly, dag should be considered as a separate trait to WEC in breeding indexes. Outbreaks of diarrhoea in young sheep are often multifactorial, and co-infections with nematodes and other infectious agents associated with diarrhoea are common. This presents challenges for the field investigation of diarrhoea in grazing sheep.
Details
- Title
- Diarrhoea associated with gastrointestinal parasites in grazing sheep
- Authors/Creators
- C. Jacobson (Author/Creator) - Murdoch UniversityJ.W.A. Larsen (Author/Creator) - The University of MelbourneR.B. Besier (Author/Creator) - Brown Besier Parasitology, 23 Cuthbert Street, Albany, 6330, Western Australia, Australia.J.B. Lloyd (Author/Creator) - Lloyd'sL.P. Kahn (Author/Creator) - University of New England
- Publication Details
- Veterinary Parasitology, Vol.282, Article 109139
- Publisher
- Elsevier
- Identifiers
- 991005541171707891
- Copyright
- © 2020 Elsevier B.V.
- Murdoch Affiliation
- School of Agricultural Sciences
- Language
- English
- Resource Type
- Journal article
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- Collaboration types
- Domestic collaboration
- Citation topics
- 1 Clinical & Life Sciences
- 1.163 Parasitology - General
- 1.163.1022 Anthelmintic Resistance
- Web Of Science research areas
- Parasitology
- Veterinary Sciences
- ESI research areas
- Plant & Animal Science