Efforts to restore wetlands and create habitats including wader scrapes through environmental schemes have the potential to bring a risk of liver fluke, an expert has said.
Dr. Philip Skuce from the Moredun Research Institute in Scotland spoke at the Teagasc national hill sheep conference last night (Thursday, February 15) regarding liver fluke.
Agri-environment schemes, Skuce said, which involve wetland/peatland restoration and the creation of wader scrapes, have a high potential to “bring a fluke risk” to land that is required to be grazed.
The presence of liver fluke in flocks, Skuce said, is now being aided by warmer, wetter summers and milder winters, along with longer grazing periods, which are ideal conditions for parasites.
In particular, he noted that the parasitic disease has developed resistance to the triclabendazole, which he called the “drug of choice for acute fluke, especially in sheep”.
Skuce noted that “most flukicides don’t kill all stages of fluke,” and said to remember the “five R’s”.
“Use the Right product at the Right dose on the Right animal at the Right time and in the Right way.”
The Scottish researcher said a vaccine for the parasite was “highly desirable”.
He did explain that achieving a vaccine was challenging for a number of reasons:
- Liver fluke are complex organisms;
- Lack of natural protection in sheep or cattle;
- Snail intermediate host to amplify life-cycle;
- Wildlife reservoir hosts to spread infection.
Practical options on the farm, Skuce said, include fencing off wet, muddy land, and where possible, land should be drained.
Depressions in the ground caused by tractor tyres or even poaching are perfect habitats for mud snails.
Testing for fluke
Testing monthly for liver fluke, Skuce said, would be “a very good start,” but he acknowledged that on hill farms, “the logistics are not straightforward.
“As an entry level, I’d be testing composite egg counts every month and see where that gets you.”
Skuce also noted that the acidic and waterlogged conditions of peat soils are not suitable for mud snails, as they prefer muddy conditions.
He referred to work undertaken on the Shetland Islands, where he said there were no snails found on the peat, but that there were thousands of snails found on the tracks where the mud was, and where the sheep were travelling on.
While the farmers were “convinced” that the peatland was causing the parasitic disease, Skuce explained that the sheep either had liver fluke from the farm already, or they picked it up on the tracks to the peatland.
Rumen fluke, Skuce explained, is something that has become “more common” in Ireland and the UK.
He did say that in cases of rumen fluke, there is “little published evidence of production impacts” on carcass quality, confirmation, and fat scores.
However, Skuce said that liver fluke is the more pathogenic parasite, and that farmers should not treat for rumen fluke when eggs are seen in samples, as this will “increase selection pressure for resistance for parasites”.