Liver fluke surveillance farms show extended challenge

Five liver fluke ‘surveillance farms’ established by the Farming Against Liver Fluke (FALF) action group have shown how the mild, wet weather of recent months has led to an extended liver fluke challenge.

Set up by Elanco in response to issues identified by FALF in 2015’s wider liver fluke awareness campaign, the surveillance farms see industry experts and the farms’ own vets working closely together to test, monitor and help manage a sustainable approach to liver fluke control on each farm.

“The liver fluke lifecycle is dependant to a large extent on the weather,” said Matt Colston, Veterinary Surgeon at Elanco. “The mild wet autumn and winter weather allowed the mud snails to remain active well into and through the winter. As long as the snails are active, more cercaria are released, increasing the metacerarial numbers on pasture, so increasing the risk of disease in grazing animals. This varies from farm to farm, and also depends on there being suitable habitats for the mud snail (Galba truncatula) which is the intermediate host for the liver fluke. Understanding this link between weather and the fluke challenge – and the need to act accordingly – is vital.”

“For our five farms, where there is a fluke challenge, the level of challenge has been maintained or is increasing, with the risk of acute or sub-acute disease still present,” confirms Matt Colston. “In these circumstances treatment with an active effective against early immature fluke is advisable. This would normally be triclabendazole, or closantel where triclabendazole resistance has been established.”

Surveillance Farm results update

Farm 1: George Milne – Kinaldy Farm, Fife

In November 2015, lambs had shown evidence of early infection (6 testing positive to Copro-antigen, no fluke eggs present) so some were treated with Closantel. January samples therefore looked at treated and untreated lambs but also ewes:

Treated lambs:

Copro-antigen – 3 positive, 7 negative
Fluke egg detection – all samples negative

Untreated lambs:

Copro-antigen – 4 positive, 6 negative
Fluke egg detection – 2 positive, 8 negative

Ewes

Copro-antigen -positive bulk sample
Fluke egg detection – large numbers in bulk sample

What next? With treated lambs showing signs of early infection, untreated lambs chronic infection, and large numbers of fluke eggs in the ewe’s bulk sample this suggests animals are still acquiring new infections, with untreated animals potentially having well established infections. All groups would benefit from treatment.

Farm 2: John Harrison – Croftheads, Dumfries & Galloway

Lambs

November – Copro-antigen – 1 positive, 9 negative
December – Copro-antigen – 7 positive, 3 negative
January- Copro-antigen – 10 positive

Ewes (December)

Copro-antigen -positive bulk sample
Fluke egg detection – large numbers in bulk sample

What next? Mr Harrison’s lambs had been showing an increasing level of infection from November 2015 to January 2016 and these samples were part of a Triclabendazole efficacy test. The Copro-antigen average increased after treatment suggesting, despite animals looking well due to the low/moderate challenge, that the treatment had not been effective. This shows the benefit of pro-active testing and all groups were then treated with Closantel.

Farm 3: Paul Capstick, Parkhouse Farm, Heversham, Cumbria

Lambs (December)

Copro-antigen – 3 positive, 7 negative
Fluke egg detection – 2 positive, 8 negative

Ewes

Copro-antigen – positive bulk sample for the first time
Fluke egg detection – large numbers in bulk sample for the first time

What next? With December lamb samples showing continued low/medium challenge and ewe bulk samples testing positive for the first time, January samples are being analysed to determine treatment options.

Farm 4: Carwyn Roberts, Garn Fach, Llanelli

Lambs were treated with Closantel in early November, subsequent samples taken were all negative.

December

Copro-antigen – 5 positive, 5 negative
Fluke egg detection – 10 negative

January

Copro-antigen – 10 positive
Fluke egg detection – 9 positive, 1 negative

What next? With December and January samples showing evidence of growing exposure and infection, and continued medium to high challenge, all groups would benefit from treatment.

Farm 5: Mr Peter Derryman, Peterhayes Farm, Honiton, Devon

Ewes (Nov & Dec)

Copro-antigen – negative
Fluke egg detection – negative

What next? Lambs are kept on low risk dairy pasture and all samples are Copro-antigen negative with no fluke eggs either which suggest no fluke challenge yet and no treatment needed.

“These results show the impact that weather can have on liver fluke levels and the need to stay alert to the challenge”, advises Matt Colston. “I urge famers, including those in areas previously thought of as fluke-free, to learn from these surveillance farms and to consult with their vets and animal health advisers to establish similar control measures for sustainable liver fluke control if they have not done so already.”

“The campaign has highlighted the need for better awareness of sustainable liver fluke management and for this to be translated into practical action, using the right product, at the right time on the right stage of fluke. A further report on the five farms will be completed towards the end of March.”

Understanding the tests available

With liver fluke growing through 3 development stages within the animal, and treatment needed for lambs and ewes, it is important to choose the right set of tests. Infection also depends upon the areas sheep have been grazing, so one group could have no challenge, whilst others are still at risk.

Fluke Antibody test – blood samples for anti-fluke antibodies will show the first signs of exposure to fluke.

Positive – indicates that lambs have already met a liver fluke challenge. However it does not tell us the level of that challenge, or whether it is likely to cause clinical disease, or decreased growth rates.

Negative – no exposure to liver fluke yet and no treatment necessary . Other groups on the farm could still be at risk, depending on the areas they have been grazing.

Copro-antigen – Specific for Fasciola hepatica, this test detects the presence of active liver fluke when the volume of “excretions” from the fluke pass a certain threshold.

Positive – indicates active liver fluke infection

Negative – No fluke, very low numbers, or fluke so small that their secretions do not exceed the threshold.

Fluke egg detection – Faecal Egg Count

Positive – egg laying adult fluke present. False positives can occur if rumen fluke eggs are mistaken for liver fluke eggs, or if all fluke have been removed but eggs are still being released from bile ducts and gall bladder.

Negative – no egg laying adult fluke present. (There could still be large numbers of immature fluke present) False negatives can occur because fluke eggs are shed intermittently, and the sample size/dilution factor may mean egg numbers are below the level of detection.

Farm Profiles

Farm 1: George Milne – Kinaldy Farm, Fife

George’s family have been farming at Kinaldy since the 1960s and he runs 120 pedigree ewes and lambs, 500 gimmers and 250 fattening hogs on 220 acres of grass plus some rough grazing. Each year he sells 30 shearling tups and he also runs 20 head of Aberdeen Angus cattle on the farm. George experienced large losses to fluke in the winter of 2012/13 and in response to the challenges he and many other farmers were facing the Scottish Fluke Action Group was formed. This group has been working on the farm since then monitoring the fluke levels and helping George make informed decisions on the best control strategy for his farm. George’s journal on his experiences of managing fluke can be found on the National Sheep Association website

Farm 2: John Harrison – Croftheads, Dumfries & Galloway

John and his wife Helen moved to Croftheads from Cumbria in 2014. Prior to this the farm was grass let, mainly for cattle grazing, for the previous 25-30 years. It is a 90 acre farm of ‘upland pasture’. John lambed 290 Lleyn ewes last year, but is reducing that to just over 200 (Lleyns and Hampshires) to tup this year. All female lambs are kept for breeding (half to keep and half to sell) with fat lambs going deadweight. Scanning figures are usually 190-210, with lambs reared at 165-180%. John is working with his vet Iain Dick from Ark Vets, Lockerbie on the fluke surveillance project.

Farm 3: Paul Capstick, Parkhouse Farm, Heversham, Cumbria

Mr and Mrs Gordon Capstick and their son Paul have been on the farm for 35 years. It is a rented farm of 580 acres in total (160 acres of 5 year leys, 40 acres of barley for feeding; the rest is permanent grassland with no marshland grazed). The main enterprises on the farm are beef and sheep – the family also host weddings. There is a herd of performance recorded Saler cattle, and a flock of around 1,000 mule ewes aiming to produce prime lamb. Last year the flock scanned at 179% with 145% reared to sale. Paul is working with his vet Judith Lee from Westmorland Vets, Kendal on the fluke surveillance project.

Farm 4: Carwyn Roberts, Garn Fach, Llanelli

Carwyn is the third generation of the family to farm at Garn Fach. It is a 260 acre farm, with an additional 100 acres rented for summer grazing. The main enterprise in the farm is the 170 cow dairy herd, but the farm also runs a 270 ewe flock (mixed breeds) producing fat lambs which are sold deadweight. Last year the flock scanned at 160% with 150% reared to sale. Carwyn is working with his vet Sarah-Jane Redman from Prostock Vets, Carmarthen on the fluke surveillance project.

Farm 5: Mr Peter Derryman, Peterhayes Farm, Honiton, Devon

The Derryman family have been farming in Yarcombe for nearly 100 years with five generation’s having worked on Peterhayes Farm. Just over 400 acres over two holdings of predominantly permanent pasture and long term leys plus another 50 acres rented. The farm carries a 120 cow dairy herd plus followers and beef cattle. The sheep enterprise consists of 100 pedigree Hampshire Downs and 120 pedigree Suffolks selling 80 – 100 performance recorded rams a year. A commercial flock of 250 Romneys scanning at approximately 180% are lambed in March to produce finished lambs which are sold dead weight. All female replacements are homebred. Peter is working with his vet Gareth Foden from Synergy Farm Health, Evershot on the fluke surveillance project.

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