Improving the control of liver fluke infection in cattle in the UK

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Liver fluke is a common parasite that affects sheep and cattle in the UK. It is found throughout the world and in some countries it affects humans too, causing serious and sometimes fatal disease.Fluke infected cattle lose weight, become anaemic, lethargic and stop being productive. This has a serious effect on the welfare of the animal and serious economic consequences for the farmer. It is thought that fluke costs UK agriculture at least £300million pounds a year through direct losses, but real costs are probably much higher. Fluke has become much more common over the past 10 years, due in part to our changing weather patterns, wet summers and mild winters favour the development of the parasite and its vector - a mud snail, found commonly throughout Britain. In a recent study we found 75% of dairy herds had evidence of fluke infection. Future climate change is predicted to have a significant impact on prevalence of infection, changing the epidemiology and increasing incidence of disease. Increased cattle movements and changes to both farm management and environmental schemes are exacerbating the problem. A limited range of drugs is available to control fasciolosis. Only one drug - triclabendazole (TCBZ), is effective against early and late juvenile and adult stages of the parasite and is used extensively for prophylaxis and treatment of disease. There is growing evidence of resistance to TCBZ in fluke populations, moreover the European Medicines Agency has recently revised its advice on drugs used to treat fluke such that they are now contra-indicated in dairy animals.Targeted use of drugs, at specific times of year will slow the development of drug resistance and reduce the overall quantity of drug used, but a better understanding of the epidemiology and transmission of disease is vital if we are to develop control programmes that rely on improved on farm management practises rather than depending solely on drugs. This ultimately will be a sustainable and cost-effective way to control both clinical and sub-clinical disease in cattle and is the express desire of the livestock industry. Specifically requested by the farming industry, the purpose of this project is to produce new, sustainable, bespoke control programmes for beef and dairy farms, to reduce losses associated with fluke infection. In order to achieve this we must first develop diagnostic tests to identify infected herds. We already have good tools that we can use on milk samples to detect infected dairy herds but we need similar tests that are appropriate for beef herds. In addition we are aware of a newly emerging parasite problem, the rumen fluke. It is not clear if this parasite causes disease but it has the potential to interfere with the diagnostic tests we are developing for fluke. Therefore we will also develop a molecular test for rumen fluke.Secondly we will develop a system to categorise snail habitats that can be used to analyse satellite maps on a regional geographic scale to obviate the need to visit every farm to investigate snail habitat. We will also investigate how cow behaviour affects how the parasite gets to a snail host and from the snail host back to the cow.These are risk factors for fluke infection on a farm. Other risk factors, particularly husbandry practices, physical and environmental factors will be obtained from a study of 250 farms and these data fed into statistical and mathematical models to determine theoretically which of these factors are the most important in determining whether a farm has fluke or not. Concurrently we will assess the cost-benefit of changing these practices. Finally we will conduct a trial to evaluate if changing farm practice is effective in reducing levels of infection. We are working in partnership with the Agricultural Levy boards of the UK to implement improved control of fluke infection to benefit animal health, welfare and profitability of livestock farming in the UK.