The number of positive liver fluke cases is beginning to rise, in line with the statement made by the Sustainable Control of Parasites in Sheep (SCOPS) and Control of Worms Sustainably (COWS) groups in October that, after a wet, mild summer and autumn, livestock farmers could be facing a high challenge for some areas.
Results of testing and post-mortem examinations in recent weeks suggest liver fluke activity in early autumn was still quite low, but the number of positive cases is now beginning to rise and SCOPS and COWS are urging farmers to keep up with testing to avoid being caught out.
Dr John Graham-Brown of the University of Liverpool and National Animal Disease Information Service (NADIS) says the recently updated NADIS forecast confirms the provisional autumn forecast, which predicted a medium to high risk on the west coast, all the way from North Wales up to northern Scotland. However, unpredictable weather patterns mean it is likely snail habitats, and therefore liver fluke, will be more widespread – and the window for infection more prolonged – than in previous dry summers. Therefore, farmers must stay on their guard and keep testing.
Speaking on behalf of SCOPS, independent sheep consultant Lesley Stubbings said, “We are particularly concerned about those farmers who have treated sheep already. Flukicides do not have any residual effect, which means a dose given too early offers no protection if sheep have been put back onto infected pastures. It is vital to establish if fluke is present – so treatment can be given at the right time.” This topic is covered in a new SCOPS podcast.
Highlighting the importance of testing for cattle and sheep, Dr Philip Skuce of Moredun added, “The coproantigen test can detect the presence of liver fluke a little earlier than faecal egg detection, which is particularly useful when the risk is considered high on a farm. But as we head into December, faecal egg count testing methods are likely to be most appropriate, particularly post-housing.”
Rebecca Mearns of Biobest warns of the potential perils of over-use of flukicides, in particular closantel. She said, “We are concerned about reports that sheep farmers are repeatedly treating sheep with closantel against Haemonchus contortus (the barber’s pole worm). Dosing at intervals of less than six weeks risks adverse effects in sheep, including blindness. If farmers then also use the same drug to treat liver fluke, the risks of overdosing are even higher. This risk is made worse because some producers have assumed they have resistance to triclabendazole, ruling out the use of this potentially useful flukicide on their farm. Talk to your vet about how you can confirm the position rather than jumping to conclusions.”
Dr Lis King of AHDB is the incoming Chair of the COWS Steering Group. She said, “While less commonly affected by acute disease than sheep, the tendency to leave cattle out for longer as a consequence of milder weather (or even all winter in some systems) could mean longer exposure to liver fluke infection on pasture. Testing is essential to gauge the degree of exposure, with a number of testing options available at or over the winter housing period.”
Find the SCOPS-COWS Guide to Test-Based Liver Fluke Control here – SHEEP – CATTLE
Related content: Fluke control & prevention, beyond testing & treatment