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New DNA test identifies sheep worm species

Sheep producers can now benefit from a new DNA test that identifies the different species of roundworms in the sheep with their proportions calculated in a fraction of the time, and with improved accuracy, compared to traditional larval cultures. This new test enables sheep producers to respond faster to worm infections and will provide a more accurate indication of drench resistance.

Researchers at the University of Melbourne, in collaboration with AusDiagnostics, developed a novel approach for the specific diagnosis of the most important roundworm species infecting sheep, including barber’s pole worm, brown stomach worm, black scour worms, small intestinal worms, large-mouthed bowel worm, nodule worms and large bowel worms.

This new diagnostic approach uses minute amounts of roundworm DNA present in the faeces of infected sheep. The test can be conducted within 2–3 days, rather than the 7 days required for the conventional larval culture technique, and has improved sensitivity and accuracy. It is still used in conjunction with a normal worm egg count, but allows the diagnosis of a wide range of roundworm parasites with high precision.

The new test is being rolled out by AusDiagnostics and has been installed at Veterinary Health Research (VHR) in Armidale, NSW (VHR in collaboration with Merial Australia) and Gribbles Veterinary in Clayton, Victoria.

Rad Nielsen, Production Animal Veterinarian at VHR said, “We (VHR) see this DNA test as being the way of the future in terms of diagnosing internal parasite infections in livestock. By providing graziers with a complete and timely assessment of worm burdens they will now be able to respond to the results within a few days of sample collection.”

Identifying the level and species of roundworm infection in a mob is essential for making optimal decisions about if and when animals should be treated, and allows producers to design control programs, and use products, that will target the particular roundworms that are present.

Rick McCoy, Veterinary Manager at Gribbles said, "With the reduction of availability of parasite testing, especially the laboratory skills to identify roundworm species from larval culture in Victoria, Gribbles sees this assay as a viable alternative to the traditional parasite testing methods.

“The assay is also suitable for pre- and post-drenching studies, identifying development of drench resistant strains, thus indicating a need to modify treatment strategies," said Dr McCoy.

By providing a more accurate measure of the proportions of roundworms, the new DNA test will enable a more accurate assessment of the level of drench resistance for each of the major roundworm species. Knowing the drench resistance status is a key component of WormBoss regional control programs.

MERIAL Australia is supporting the new DNA test across Australia and MERIAL E-DNA test kits (for use at the VHR laboratory) are now available for sheep graziers in leading rural resellers.

A similar test for the most important roundworms of cattle has already been developed by AusDiagnostics. The cattle test is currently being trialled and will become available to livestock producers in Australia and Europe towards the end of 2014.