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Roundworm transmission in farmed UK ruminants

Gastrointestinal roundworms infections (GINs) are common and considered one of the top three production-limiting pathogens of ruminant stock in the UK.

On most farms roundworms occur as co-infections with other parasites (multiple roundworm species, fluke and/or ecto-parasite) as well as bacteria and viruses.  Control of most parasites is based on a variety of chemical (anthelmintics/drenches) and non-chemical treatment options that can be adapted to individual farms.  Unfortunately resistance to these chemicals is developing in many roundworms.  With this fact in mind, the PhD project has three main aims:

  1. to better understand roundworm epidemiology in farmed ruminants, through the use of parasitological and statistical methods;
  2. to use DNA sequencing technologies to explore roundworm diversity and white drench (benzimidazole) resistance frequency in UK roundworm populations;
  3. to utilise spatial modelling to explore potential transmission risks and to better understand what might happen to worms post their introduction with new untreated stock onto pasture.

The data so far shows a high prevalence of roundworms in UK farmed sheep, with moderate prevalence in farmed cattle and low in farmed deer. Statistical analysis is ongoing, to explore potential host and environmental factors that could influence roundworm prevalence. The brown stomach worm (Teladorsagia) and the black scour worm (Trichostrongylus) have been identified as the most common in our sheep populations, and Ostertagia and Cooperia the most prevalent in cattle In the sheep samples, the highest frequency of benzimidazole resistant alleles was found in the same species listed above, the highest frequency being 68% in Teladorsagia species, with analysis of the resistance data for the cattle to be completed. As stated above, the project will utilise spatial modelling based on location data obtained during the project, in order to ask the question, “what is moving around the UK?”. In addition to this question, we also want to know “what is ending up on farm?” and this will be answered through the use of a mathematical model (GLOWORM-FL).

The data collected during the PhD project will hope to be the building blocks for updated recommendations for farmers and market owners, by better understanding the risks associated with the transfer of roundworm through animal movements particularly untreated animals.

The project was funded by the Veterinary Medicines Directorate and Scottish Government’s RESAS division.

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