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

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.

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 F. hepatica. This is a focussed, integrated project combining cutting-edge mathematical and economic models, informed by data collected from the field culminating in farm level intervention programmes to fully evaluate the theoretical outputs from the models. The project is divided into five interlinked workpackages:
WP1: Development and validation of herd level diagnostic tests, to identify farms with fluke infection and to discriminate between Fasciola and paramphistome infection
WP2: Field level classification of snail habitats and identification of factors that influence contacts between cows, snails and the parasite.
WP3: Identification of on farm risk factors for F. hepatica infection in dairy and beef enterprises and development of statistical and mathematical models to predict the likely benefits of implementing changes to farm practice on fluke prevalence
WP4: An economic analysis to define costs of fluke infection at herd and national level
WP5: Evaluation of on-farm intervention programme on reducing prevalence of fluke infection on dairy and beef farms.
The disease is of such importance and relevance to the industry that all five UK agricultural levy boards are making significant contributions to this project. To ensure the outputs of the research are fed back to the industry the final component of the project is an implementation and impact programme in collaboration with the levy boards.

This project, aimed at "Improving the control of liver fluke infection in cattle in the UK" will benefit the commercial private sector, policy makers and the wider public.
Commercial impact
Liver fluke has been identified as a threat to animal welfare, productivity and profitability by the agricultural industry; this proposal is submitted with full support from the 5 UK Levy Boards. Fasciolosis is a significant constraint on beef and milk production in the UK. The parasite affects feed conversion, growth rates and milk yield and has a negative impact on farmers' incomes, abattoir profitability (in 2010 this was estimated to cost the industry about £3.2million in England, Wales and Scotland) and availability of meat and dairy products for export and home consumption. Cereal costs are increasing world wide - this is severely affecting the cost and profitability of producing beef and dairy and appears to be driving a move to grass reared beef. Grass-fed cattle are at an increased risk of exposure to liver fluke. In addition, warmer and wetter winters, environmental protection schemes, resistance of liver fluke to drugs, and the potential withdrawal of treatment products from the market may add to the risk of infection and limit the options for disease control. The outputs from this project will directly benefit beef and dairy farmers, enabling them to improve fluke control on their farms, reducing reliance on blanket drug treatment and improving productivity and biological efficiency. Abattoirs will have a secure supply of animals with reduced waste, dairy processing companies will benefit from improved milk yield and the retail sector will benefit from improved local production. Overall this will benefit the wider UK economy.
Policy impact
The UK has international (Kyoto Protocol) and domestic (Climate Change Act 2008) targets to reduce greenhouse gas (GHG) emissions. Enteric fermentation in ruminants makes a significant contribution to agricultural GHG emissions (http://www.decc.gov.uk/en/content/cms/statistics/climate_stats/gg_emissions/gg_emissions.aspx). Disease management has been specifically identified as a tool to improve agricultural productivity whilst reducing GHG emissions (Foresight. The Future of Food and Farming, 2011). This project will produce validated protocols, epidemiological and economic models and robust guidelines for detection and management of liver fluke on cattle farms, which will contribute to the dual policy aim of providing food security whilst limiting agriculture's carbon footprint. Another policy goal of the UK and devolved governments is to protect the country's Ecosystem Services. For example, it is part of Defra's business plan to establish nature improvement areas (http://www.number10.gov.uk/wp-content/uploads/2012/05/DEFRA-2012-Business-Plan.pdf). However, environmental protection schemes may result in unintended side effects as shown by the increase in liver fluke risk in association with the Agri-environment schemes that encourage wetter grassland conditions for breeding and migrating birds and invertebrates, including liver fluke host snails. Improved understanding of on-farm risk factors for liver fluke, including snail ecology, will help policy makers to balance demands from competing ecosystem services, such as food production and conservation of biodiversity. Involvement of the Levy Boards will ensure direct dissemination of the outputs to both commercial beneficiaries and policy makers.
Wider public
The reliable availability of affordable and healthy food is in the interest of the wider public. Beef and dairy product supplies, their quality, environmental impact and price depend on an international balance of trade which will be affected by the prevalence of fasciolosis. Our economic models will include an assessment of impacts on national markets and hence indicate consumer benefits from a more secure supply of food, produced to higher environmental and welfare standards.