Gastrointestinal nematode (GIN) infection is a major disease in cattle and sheep that has major global socio-economic importance. Control of the disease relies heavily on chemical treatments, but many parasites are developing drug resistance, which is causing treatments to fail.

Targeted treatment can be used if animals with large burdens of nematode parasites are identified through observed symptoms or tests that monitor the number of worm eggs in the dung of the animals – known as a faecal worm egg count (FEC) test. Targeting the treatment can reduce the amount of chemicals used, slowing the development of drug-resistant parasites. However, monitoring livestock for these indicators is generally not cost efficient.

A new tool for monitoring levels of infection dramatically reduces costs

In 2005, Dr Eric Morgan, Senior Lecturer in the School of Veterinary Sciences, developed methods that optimised a testing method that offered farmers a more economical means of monitoring levels of nematode infection in their livestock. The test, known as a composite FEC test – was validated by Morgan and the Animal Health and Veterinary Laboratories Agency (AHVLA) and was made available in AHVLA regional laboratories in 2006.

Since then, over 2,000 composite FEC tests have been conducted at a cost of just over £52,000 to farmers, realising a saving of 74 per cent on previous treatments – the equivalent analyses of which would have cost farmers a combined total of over £193,000. As well as this direct cost savings in terms of testing, FEC monitoring can also lead to a decrease of as much as 75 per cent in the number of treatments given to lambs.

Surveys of farmers at Sheep South West Meetings in 2007, 2009, 2011 and 2013 are showing an increasing awareness of FEC monitoring and its value in slowing the development of nematode resistance to treatments.

Understanding the impact of climate change on disease

Dr Morgan’s research has also looked at how seasonal patterns in clinical nematode disease are changing as a result of climate change. Specifically, Dr Morgan and colleagues were the first to describe how temperature influences the development, hatching and survival of the larval stage of the nematode Nematodirus battus – a highly pathogenic sheep parasite.

The insights into this organism’s ecology are feeding directly into predictive simulation models that are being used to improve disease forecasts. The forecasts, which are issued by the Sustainable Control of Parasites in Sheep (SCOPS) group, were accessed more than 10,000 times by farmers and their advisers last spring. The SCOPS initiative was formed in response to the realisation that anti-parasitic drug resistance could become one of the biggest challenges to sheep production and welfare in the UK if left unchecked

Both the composite FEC test and the seasonal changes in the risk of nematode disease have been incorporated in official recommendations to veterinarians and farmers through the SCOPS initiative. In 2012 it released the fourth edition of a technical manual for veterinary surgeons and advisers, which incorporated advice based on the research conducted at the University of Bristol.

Case studies of farms that have adopted the SCOPS principles have demonstrated the value of FEC monitoring and realised significant improvements in flock performance.