15th March 2023

New research shows farmer confusion over the diagnosis and control of rumen fluke and liver fluke.

Despite rumen flukes being present in Great Britain for 50 years or more, it is only in the past decade that they have been regarded as potentially pathogenic parasites. This may coincide with the establishment of Calicophoron daubneyi as the main rumen fluke species. How it arrived or why it has now spread across the country is not known, but increasing cattle movements from Europe where it has been present for many years, and/or climate change may be responsible.

Liver fluke disease has been estimated to have significant economic implications for UK Agriculture, possibly as much as £300 million a year. The economic significance of rumen fluke remains unknown.

Research carried out at Queen’s University Belfast in 2019, showed there to be no difference in the carcase weight of cattle infected with rumen fluke compared to those not infected1. Similarly carcass conformation and fat class were unaffected. In a second trial, daily liveweight gain (DLWG), diarrhoea score and welfare score of dairy heifers were not affected by rumen fluke infection or by oxyclozanide treatment against rumen fluke. These results suggest that on well-managed farms, growth rates should not be compromised because of sub-clinical rumen fluke infection.

“Generally, cattle infected with adult rumen fluke seem to tolerate them quite well,” says PhD student Rebecca Hoyle from the University of Liverpool. “But there have been a few cases where youngstock heavily infected with immature stages have become very ill and died. Lack of diagnostic tests to detect immature rumen fluke is not helpful.”

Keen to gauge the level of farmer awareness of rumen and liver fluke and the current control practices being used across the UK, Rebecca devised an online questionnaire sent to cattle and/or sheep farmers between December 2019 and March 2020.2 Out of 451 usable responses, 86% had sheep, 46% had suckler cows and 25% beef stores or fattening cattle. Eight per cent had dairy cows.

Most of the farmers were aware of rumen fluke (70%), while almost all were aware of liver fluke (99%). Of those aware of rumen fluke, 20% reported the presence of rumen fluke on their farm, 29% reported the absence of rumen fluke infection and 51% did not know if there was rumen fluke infection present on their farm.

Currently the only way to detect rumen fluke is through post mortem or faecal egg counts (FECs). Of the respondents who reported rumen fluke on their farm, 57% had used FECs and 25% cited post mortem. The remainder said they had used other methods, often used to detect liver fluke. However, these would not have detected rumen fluke.


The majority of those who treated their cattle against rumen fluke reported treating annually. Others treated when required or every other year or every two to three years. In 2019, in total 32 farmers treated 41 times, mostly in autumn or winter. Only 42% of treatments were with oxyclozanide – the only anthelmintic known to kill rumen fluke. This is licenced for use against liver fluke but needs a veterinary prescription for it to be used to treat rumen fluke. (Figure 1)

Fig. 1. Farmer reported anthelmintic used in the treatment of cattle for rumen fluke shown as percentage of reported treatment events in 2019.

“Current recommendations in the treatment of liver and rumen fluke advocate a diagnostic led approach,” says Rebecca. “The results of our study show this is not always the case and there is confusion amongst farmers about liver and rumen fluke and their control,” Rebecca concludes.

Professor Diana Williams, also of the University of Liverpool and a member of the COWS group agrees.

“Increasingly laboratories will record the incidental presence of rumen fluke eggs in faecal samples they are testing, but this does not indicate a need to treat.

“A positive egg count only indicates the presence of adult rumen fluke in the rumen. On the very rare occasions that rumen fluke cause disease, it is due to large numbers of immature rumen fluke in the duodenum. These would show as negative on faecal egg counts.

“Liver fluke remains the most important of the two fluke parasites. Co-infections of both are common, but any treatment should focus on liver fluke.

“The experts that sit on COWS believe that anecdotal reports of production or health benefits in response to treatment of rumen fluke are unlikely to be due to the removal of adult rumen fluke. They are much more likely to be as a result of removing co-infection with liver fluke that may not have been reported.”


  1. Atcheson, E., Lagan, B., McCormick, R., Edgar, H., Hanna, R.E.B., Rutherford, N.H., McEvoy, A., Huson, K.M., Gordon, A., Aubry, A., Vickers, M., Robinson, M.W., Barley, J P. The effect of naturally acquired rumen fluke infection on animal health and production in dairy and beef cattle in the UK. Frontiers in Veterinary Science (2022) doi:10.3389/fvets.2022.968753
  2. Hoyle, R.C., Vineer, H.R., Duncan, J.S., Williams, D.J.L, Hodgkinson, J.E. A survey of sheep and/or cattle farmers in the UK shows confusion over the diagnosis and control of rumen fluke and liver fluke. Journal of Veterinary Parasitology 312 (2022) 109812