One of the big livestock problems following last year’s wet weather has been the spread of liver fluke. While this parasite has long been a problem in wetter areas, it is now endemic across Scotland.
Liver fluke affects both cattle and sheep. Low infection levels cause animals to become unthrifty – but extreme levels of infestation cause death.
Yesterday, a summit meeting on the problem was held at the world-renowned Moredun Research Institute in Edinburgh, where it was announced that a Fife farm had been selected for a pilot project to gain a better understanding of the facts behind the recent explosion in cases.
The host farmer is George Milne, of Kinaldy, St Andrews. In the past year, Milne – who is also development officer in Scotland for the National Sheep Association – suffered losses from his sheep flock due to liver fluke.
Describing these losses as “significant”, he said yesterday that he was not only taken aback to discover fluke in such numbers on an east coast farm but also disappointed to find that he was having difficulty controlling the problem using tricabendazole flukicides. Resistance to what has been regarded as the standard medication is a possibility, but Milne acknowledged that the problem seemed to vary from farm to farm. As far as Kinaldy is concerned, it is to be studied by experts from SRUC and Moredun with backing from the Scottish Government Veterinary Service.
Moredun’s Dr Philip Skuce, a world expert on liver fluke, hailed yesterday’s summit on the subject as “unprecedented”. He said the disease was presenting an “ever-changing picture”.
He continued: “A cold spring and a dry June might have been thought to have made a difference, but we are obviously still living with the aftermath of last year. Fluke can live quite happily on grass leaves through quite cold weather and it looks like animals grazing intensively when growth did start this spring may have picked up the parasite.”
Fiona Anderson, of pharmaceutical firm Novartis, said there had been concerns about the effectiveness of tricabendazole flukicides but there was still no other active ingredient that could kill juvenile fluke.
“We are looking very hard at this,” she said. “It may be that farmers are not using the right dose rate or dosing at the wrong time, but it could also be because re-infestation is occurring so quickly.”
Tribacendazole has no residual effect and with the sort of massive fluke burden on pastures last year it would not be long before sheep would ingest large numbers of juveniles.
Dr Skuce added that field management also had a part to play. “Make the field environment as inhospitable as possible for the mud snails which act as intermediate hosts for the fluke. Drainage of wet areas would help – as would fencing them off,” he said.
Pesticide application across infected fields was not a possibility with the only chemicals capable of killing the mud snails banned “decades ago”.
Scotland’s Chief Veterinary Officer, Sheila Voas, said, “I really urge farmers, including those in areas previously thought to be fluke free to consult with their vets to establish prevention and control measures if they have not already done so. There is evidence that fluke is becoming resistant to the drugs commonly used to treat the disease which is why it is so important that we establish the best control and prevention strategies.”
NSA president John Cameron, who chaired yesterday’s proceedings, said farmers were perplexed by the twin phenomena of drug resistance and rapid spread into new areas of the country.
He urged farmers to share information and to take simple measures such as submitting dung samples for testing. He also called on abattoirs and fallen stock companies, where possible, to increase their reporting of fluke infestation.
“Fluke is a growing problem. I know from my work on the Scottish Government’s weather aid committee that many of the losses recorded this spring were due to sheep being weakened by liver fluke. It partly explains why losses were so high.”