Development of molecular tools for the rapid assessment of benzimidazole resistance and investigation of possible risk factors in resistance development in nematodirus battus populations (PhD)


Prevalence results

What it means:
Potential action points:

Mutations associated with white drench-resistance are present in UK N. battus populations at a low frequency


Anthelmintic resistance is currently at an early stage in this species


The early stage of resistance in this species offers the opportunity to investigate the origin(s) of anthelmintic resistance

F200Y present in ¼ of farm populations tested


Despite the low frequency overall, the widespread distribution of the F200Y mutation could develop into clinical drug failure in the future given the appropriate selection pressure


Use the results of risk factor analysis to reduce the likelihood of further development and dissemination of resistance

Potential barriers to the development of white drench resistance

What it means:
Potential action points:



Mutations associated with white drench-resistance in N. battus are more likely to be introduced from another source than originate on farm


Knowledge exchange programs highlighting the importance of effective quarantine

Practical, easy to follow guides promoting best practice quarantine

Beef & Lamb
Project code:
01 January 2015 - 31 December 2017
AHDB Beef & Lamb
AHDB sector cost:
Total project value:
Project leader:
Moredun Research Institute


61110036 Final Report May 2019

About this project

The Challenge:

Nematodirus battus is a parasitic roundworm that infects and affects young lambs. Heavy infections cause acute diarrhoea (scouring) which can lead to death by dehydration.  Significant numbers of young lambs can be lost to N. battus infections annually if they are not treated correctly. This parasite is controlled using anthelmintic drugs (wormers), typically with white drenches containing benzimidazole (BZ) as the active compound. BZ wormers have been licensed for use in livestock for more than 50 years. In part due to their intensive usage, resistance to these drugs is now widespread worldwide in a number of roundworm species however, resistance to this drug class was not historically observed in N. battus. The first report of BZ-resistance in N. battus was in 2010 when a farm in Northern England submitted faecal samples to the Animal and Plant Health Agency for assessment following apparent treatment failures in lambs. Subsequent analysis confirmed the presence of BZ resistant N. battus.  BZ-resistance is believed to be caused by a single nucleotide polymorphism (SNP); this is a DNA mutation involving a single base change. Preliminary research confirmed that BZ-resistance in N. battus is caused by the same SNP mutation found in other BZ-r nematode species.

The Project

This project aims to characterise BZ-resistance in N. battus in the UK by:

  1. Developing a molecular assay for rapid detection of SNP mutations in battus populations
  2. Collecting and analysing samples from UK farms to map the current spread of the BZ-resistance genes in battus
  3. Developing and disseminating a questionnaire to gather information regarding farm management and climatic factors which may be influencing the development and spread of BZ-resistance in battus


Lynsey Melville