Fluke Control Needs ‘Belts and Braces’
The devastating fluke outbreaks of 2008 and 2009 could be set for a repeat performance in 2011 according to recent forecasts.1 A wet summer has resulted in predictions that a high to very high prevalence of disease due to liver fluke could occur in Scotland, Wales, Northern Ireland and Western England. Now, vets at Elanco Animal Health are warning that its time to think about what constitutes best practice flukicide treatment. A belt and braces approach will help farmers get on top of the fluke problem in the years when fluke numbers peak. Longer term, we also have to think about sustainable approaches to treatment that will help control the fluke population into the future, says Nigel Underwood, Ruminant Business Unit Manager at Elanco.
So, just what has changed about the approach to liver fluke and what still needs to change? A more strategic treatment programme has been widely advocated, based on rational conclusions about fluke and its lifecycle and many farmers are shifting their ideas about fluke control as a result. Planning the timing of treatment is the first step. October treatments are traditional but this autumn, a September treatment may yield better results in some areas. Farmers are advised to speak to their animal health adviser or vet to find out if this would be a useful strategy on their farm. A second dose 6 weeks after the first may also be needed in high fluke areas.
Another example of strategic use is in treating adult fluke with a flukicide that disrupts egg shedding by the parasite. Closantel (Flukiver) interrupts the fluke lifecycle for 13 weeks by killing adult and immature fluke older than 5 6 weeks, while stunting younger immature fluke and reducing the hatchability of fluke eggs passed out in faeces.2 In other words, using the right product at the right time can reap rewards.
The choice of flukicide should, of course, always be considered carefully. Triclabendazole resistance has been reported in a number of flocks, with a recent report detailing the economic consequences of resistance in a 2200 ewe flock in Scotland reaching somewhere in the region of 9 per ewe.3 When treating in areas like this where fluke has been endemic for many years, farmers are advised to think about their choice of flukicide, as repeated use of the same product year after year could lead to the development of resistance. Retaining those products for the situations in which they are really needed to tackle immature fluke makes a lot of sense and there are many products that can be used in rotational systems, such as closantel (Flukiver), which has not been associated with resistance in the UK fluke population.
Monitoring is another strand of the strategic approach. Bought in animals from flukey areas may also act as hosts for resistant fluke and cause resistance to develop throughout the flock. Measuring the response to the flukicide in-use, through faecal egg counts after treatment, may help give some early indications as to whether the treatment is working and may identify when resistance has started to become an issue.
A final element of the belt and braces approach is to use good management practices, such as drainage of boggy land and snail control. Given the long history of fluke and its spread into previously non-fluke areas, its clear that those particular challenges are still proving problematic to implement effectively. In Nigel Underwoods opinion it could be a long haul, The issue with fluke control is that we need to think beyond fire fighting today and project our thinking forwards to how our actions now will affect the future challenge from fluke. Many experienced farmers in fluke endemic areas are already beginning to realise just that. Its not just about giving that routine October dose of flukicide, we need to think much harder about the which, when and why of flukicide use. Only when we all do that will we really be making major advances towards a fluke-free future.
Flukiver 5% w/v Oral Suspensioncontains 50 mg/ml closantel Legal category POM-VPS.
For further information contact Elanco Animal Health, Lilly House, Priestley Road, Basingstoke, Hampshire, RG24 9NL, Tel 01256 353131, Fax 01256 779510 www.elanco.com
Advice on the use of this or alternative medicines should be sought from the medicine prescriber
Use Animal Medicines Responsibly www.noah.co.uk/responsible
References
http://www.nadis.org.uk/Current%20Bulletins/Parasite%20Forecast.pdf
Maes L, Vanparijs O, Lauwers H, Deckers W. Comparative efficacy of closantel and triclabendazole against Fasciola hepatica in experimentally infected sheep. Veterinary Record, Vol 127 No 18, 450-452 (1990)
Sargison N, Scott P, Diagnosis and economic consequences of triclabendazole resistance in Fasciola hepatica in a sheep flock in south-east Scotland, Veterinary Record 168, 646