Liver Fluke 

Measuring TCBZ resistance as part of a Whole Farm Strategy for the control of Liver Fluke in Sheep and Cattle


Suspected cases of liver fluke parasites resistant to the drug of choice, Triclabendazole, TCBZ (FasinexTM) have  been reported for over ten years in Welsh sheep and cattle (Thomas et al., 2000). Without pro-active intervention resistance in liver fluke is likely to establish as outbreaks of liver fluke continue to spread (VLA reports 1995-2010).  There is a small window of opportunity to slow the development of resistant liver fluke in Wales, and avoid the problems associated with controlling nematode infections of livestock. Testing for resistance can be problematic and the fear is that farmers will switch unnecessarily to inferior products to avoid a ‘resistance' problem developing on their farms. IBERS has developed a test to establish whether fluke are actually resistant to TCBZ. This new resistance testing approach was incorporated into the project to establish the prevalence of resistant populations of liver fluke in beef cattle and sheep.


  • To survey the level of resistance to TCBZ in Welsh flocks and herds
  • To develop a test based on the behaviour of parasite infected animals as a potential new field surveillance parasite infection tool
  • To disseminate findings to the meat industry and increase awareness of liver fluke and the significance of drug resistance.
  • To provide potential liver fluke solutions to farmers and vets and support a Welsh Liver Fluke control plan
  • To provide increased confidence to prolong the working life of TCBZ if ambiguity exists over drug performance,

Expected benefits

Further translational funding was required to deliver a liver fluke resistance test to the market place. It was anticipated that data from this project would provide a portfolio of evidence to encourage sponsors to support the development of a resistance measuring prototype kit for farm level validation prior to commercial release. In the absence of new flukicides, prolonging the working life of the only drug that targets pathogenic juvenile liver fluke is a control priority. This project aimed to assist veterinarians in understanding why TCBZ failure has occurred ensuring the correct liver fluke control steps can subsequently be undertaken.

  • This project was funded by HCC and was undertaken by IBERS, Aberystwyth University.
  • The project finished in January 2012.

To read the final report, click here

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