Helminth (worm) parasites cause around 55% of all farm animal diseases. These parasites impact hugely on livestock productivity by affecting growth rates, fertility, meat quality, wool or milk production, and sometimes cause death. One of the most important parasites to impact animal production in the UK/Ireland (and throughout the EU) is the liver fluke, Fasciola hepatica. It infects more than 300 million cattle and 250 million sheep worldwide resulting in losses of over $3 billion to global agriculture through lost productivity. In the UK it costs the cattle farming industry alone around £23 million each year as a result of poor animal condition and a significant reduction of milk and meat yields. Worryingly, resistance to the frontline chemical treatment for liver fluke (a drug called triclabendazole) has become widespread leaving farmers with little to combat the disease. Until recently, infections by similar parasites called paramphistomes, or rumen fluke, were regarded as being of minor importance. However, over the last few years increasing reports of production losses from farmers in Great Britain and Ireland have been ascribed to infection by rumen fluke. It is now believed that rumen fluke has become a bigger problem than liver fluke in many areas. In order to meet the growing threat to food security posed by rumen fluke infection it is imperative that we act now. In this project we will answer some basic questions about its biology, its impact on animal health and productivity and will develop new tests that will allow more rapid and specific diagnosis than currently possible. Specifically, we will address three main questions: 1) What is the extent of the rumen fluke problem in the UK? 2) What is the impact of rumen fluke on animal performance, health & welfare? 3) Can we develop a rapid and specific diagnostic test for rumen fluke? Our approach is timely and will determine the extent of the problem in the UK and for the first time determine a measurable impact of infection on animal production in both cattle and sheep. Furthermore we will have produced rapid and specific diagnostic tests that will allow appropriate control measures to be put in place. These important findings will allow more effective management practices to be put in place early and give us a realistic chance of avoiding the problems of drug resistance currently seen with liver fluke.