WP 1 Innovative strategies for the control of nematode infections in sheep & goats: Targeted Selective Treatments

Introduction

Workpackage 1 in Parasol examines ways of targeting anthelmintic treatments to focus them on those animals most susceptible to infection and thus at risk of disease and/or those animals that make a disproportionate contribution to pasture contamination. By only treating these ‘at risk’ and ‘risk producing’ animals, rather than the whole flock, it should be possible to maintain a worm population unexposed to anthelmintic (in refugia) that will in turn help to retain anthelmintic susceptibility within the population whilst maintaining high levels of health and welfare. The principal of targeted selective treatments (TST) was first proven in studies using conjunctival colour as an indicator of anaemia caused by Haemonchus infection. The Famacha system has conclusively demonstrated that it is possible to markedly reduce anthelmintic usage whilst maintaining acceptable levels of productivity.

Objectives

Unfortunately, this system can only be used for those parasites that cause anaemia and thus research within Parasol is examining a range of markers of infection that can be used to target treatments. These include parasitological markers such as faecal egg counts and some of the symptoms of infection such as liveweight gain, body condition score and diarrhoea index. Field studies conducted by the various partners within Parasol will use these markers to target treatments and determine the consequences of using this approach for animal productivity and parasite population dynamics. The TST approach not only needs to offer effective control of nematodoses but in order to be sustainable must reduce the rate of development of anthelmintic resistance. The TST studies in Parasol will also examine the resistance/sustainability issue by determining the phenotypic and genotypic consequences of using targeted treatments.

Expected results

The overall aim of Parasol is to produce regionally appropriate control strategies incorporating the TST approach. Since being able to demonstrate the validity of targeted selective treatments will not in itself ensure its acceptance by the farming community another important aim of the workpackage will be to use a questionnaire to try to understand and overcome the key acceptability issues.

Organization

The partners involved in WP 1 are the Moredun Research Institute and the INRA in Tours.