17th October 2013

Liver fluke workshop highlights scale of liver fluke threat

With peak liver fluke season looming, more than 80 farmers, along with vets and others, attended a liver fluke workshop last week to hear the latest advice on tackling the increasing problem of fluke infection.

The Quality Meat Scotland workshop, hosted by the Moredun Research Institute, focused on the current fluke situation and methods of control.

Fluke infection costs the UK agriculture industry around £300 million per year due to production losses, with liver condemnations alone costing £3.2 million in 2010.

“Evidence from various sources suggests that the prevalence of infection has increased considerably in recent years,” said Dr Philip Skuce, Senior Research Scientist at Moredun.

“Changing weather patterns, leading to mild winters and wet summers were thought to be primarily responsible, as these conditions favour the fluke’s survival in the environment. However, increasing reports of drug resistance and increased animal movements and changes to farming management practices may also play a role.”

Experts from the University of Liverpool, Scotland’s Rural College, and the Centre for Ecology & Hydrology joined those from the Moredun to dispel some of the myths around the management of liver fluke.

Working with George Milne from the National Sheep Association and Callum Harvey from Harbro, the scientists examined the current situation and looked at how last year’s weather may continue to affect fluke infection rates this year.

The team reported that there had been a 10-fold increase in fluke incidence being reported in the last quarter of 2012 compared to the same period in 2011 and this was specifically attributed to the exceptionally wet summer experienced across most of the UK last year.

In addition to discussing drug-based means of controlling fluke, the role of the mud snail and the environmental conditions that favour its survival and reproduction were examined.

The conflicts between environmental schemes that favour biodiversity and the management practices needed to keep livestock fluke-free were widely aired. The experts identified the importance of the algae that the snails feed on and how its growth could be reduced for example by providing dry standing around water troughs and reducing poaching of the land.

“There are growing concerns about drug resistance and, unanswered questions for example what happens to fluke cysts and eggs in silage, slurry or hay,” commented Prof Charlotte Maltin, Science and Innovation Manager at QMS.

As fluke affects its host’s immune system and can affect diagnosis and susceptibility to other pathogens, including bovine tuberculosis, new means of controlling fluke are urgently needed.

Tackling the Threat from Liver Fluke – Top 10 Actions for Cattle Farmers

1. Identify high risk areas of fluke and consider if grazing these pastures in the late summer /autumn can be avoided. Practical steps include fencing off wet areas, attending to leaking troughs and pipes, drainage or even consider housing early.

2. Ask for abattoir feedback on any liver rejections. This is a free and invaluable option for getting an early warning that there may be a fluke problem on a farm. Early action will minimise reduced performance due to sub-clinical liver fluke infections.

3. Investigate losses in sheep if you have sheep on your farm, as this can be an indication of fluke risk for your cattle.

4. Treat your cattle using the most appropriate drug, most suitable for time of year and management of cattle involved. Be sure to understand the product choices available in terms of the age or stage of liver fluke to be targeted because there are distinct differences in the effect of flukicides. Consider meat and milk withdrawal periods as well. Only use a combination product if appropriate – at housing for example, when fluke, lungworm and gut worms may all need to be controlled, but check with your vet or suitably qualified person (SQP) and make it part of your parasite control plan.

5. Always treat effectively. Under-dosing is a major issue, leaving parasites alive in the animal which will cause damage to the liver and encourage resistance to develop. Weigh, don’t guess, and be prepared to split cattle groups if there is a wide variation in liveweight to ensure the dose rate is accurate. Calibrate equipment regularly for all means of administration (drench, pour-on or injectable). If the product is orally administered ensure the drench is delivered over the back of the tongue. Follow the prescriber and manufacturer instructions for storage and administration accurately.

6. Consider if you need to reduce pasture contamination levels in spring/summer by using a treatment with a drug that kills adult fluke (see table overleaf) to kill egg laying parasites.  This should be based on individual risk factors and abattoir feedback.

7. Remember to repeat the treatment if necessary.  If you leave cattle on infected pasture after treatment you may need to re-treat them in six to 12 weeks depending on the product you use.  None of the flukicidal products are persistent so animals can pick up infection straight away after treatment.

8. Resistance to some flukicides is increasingly prevalent in sheep, so it is important to have an effective control plan for cattle that reduces the risk of resistance spreading.  If you suspect resistance, arrange a drench test, i.e. a Faecal Egg Count Reduction Test (FECRT), with your vet/SQP.

9. Quarantine all incoming stock (sheep as well as cattle) from potential fluke areas for liver fluke as well as roundworms. This will take considerable planning but failure to do it could result in importing resistant liver fluke from another farm as well as losses and/or reduced performance in the animals themselves. Refer to guidelines on the COWS/SCOPS website (www.cattleparasites.org.uk & www.scops.org.uk) and discuss with your vet/SQP.

10 Be Prepared. Don’t wait until the losses are mounting up. Act now to work with your vet or SQP to plan ahead in terms of management control options, treatments and monitoring that can be put in place.

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