Unusual weather patterns are having a big impact on the risk of liver fluke across the UK, say livestock experts.
The level and timing of the disease risk is becoming later with the first losses last year no reported until late November, according to the Sustainable Control of Parasites in Sheep (SCOPS) and Control of Cattle Parasites Sustainable (COWS) groups.
Experts say the dry cold spring, hot early summer and extremely wet July and August – followed by a mini-heatwave in early September and heavy rain throughout the autumn and early winter – all contributed to the disease picture.
Rudolf Reichel, of the Animal and Plant Health Agency, said: “There was little evidence of liver fluke activity in the autumn, but towards the end of the year we started to get reports from abattoirs and private post mortem providers of acute fluke cases.
He added: “This was mirrored by other laboratories across the country and, while overall numbers of cases are not high, this does represent a significant increase in recent weeks.”
John Graham-Brown, of the National Animal Disease Information Service, said the delayed threat raised the prospect that some farmers could get caught out – either treating too early or thinking they were safe from the disease altogether.
Philip Skuce, from the Moredun Research Institute, has similar concerns. Rather than being lulled into a false sense of security, he urges farmers to continue testing for liver fluke during early 2024.
“Flukicides do not have any residual activity, which means there is no protection for treated livestock if they meet a challenge from fluke later in the season. The risks are so farm-specific this year that the only way to avoid potential losses is to keep testing.”
Rebecca Mearns, of the Sheep Veterinary Society, said: “Until quite recently, most samples were negative. Do not rely on an early negative test. If you keep livestock, you need to keep testing throughout the season.”
Faecal testing
Diana Williams, of Liverpool university, said: “During January and February, when we would expect adult flukes to be present in the livers of infected livestock, we can also use faecal testing methods.”
Dung samples can be tested for an antigen produced by the liver fluke (coproantigen) and of course the detection of fluke eggs is also a valuable tool. Ask your vet or adviser which test is most appropriate for your farm and never rely on a single negative test.
Professor Williams said: “The only test that can be used with pooled samples is the faecal egg count. This is because the sensitivity of a pooled test is much lower and may give a negative result even though one or more animals are positive.
“For faecal egg counts the whole pooled sample is processed, so the sensitivity remains comparable with testing individual samples. For blood tests and copro-antigen tests, individual samples should be tested.”
