Barber’s pole worm, Haemonchus contortus, is one of the major sheep parasites in Australia, causing significant economic and production losses, especially in areas with summer rainfall patterns. Barber’s pole continues to be problematic as it has demonstrated an ability to rapidly develop resistance to chemical treatments, due to its short lifecycle and high production of eggs under the right conditions.
Barber’s pole is a blood-feeding worm that matures in the abomasum and can have serious implications for sheep health, welfare and productivity. Signs of acute infections include anaemia, lethargy, collapse and death. Chronic signs may include significant reductions in wool growth, weight gains, milk production and bottle jaw (sub-mandibular oedema).
With the shortest lifecycle (20 days) of any gastrointestinal nematode and highly prolific female worms laying around 10,000 eggs per day under ideal conditions, worm numbers can build up quickly on pastures. As a result, disease outbreaks can occur rapidly and with little warning, and resistance to drenches can develop within just a few years of a new active becoming available1.
Barber’s pole prefers warm, higher rainfall climates as this creates the ideal environment for prolific reproduction and rapid build-up of worm numbers in sheep and on pastures. Its distribution appears to be extending2 and in unseasonably wet, warm summers, barber’s pole can appear in localised pockets in any state.
Summer and autumn are the greatest risk periods for sheep health. However, eggs deposited in late summer and autumn may develop into infective larvae that persist through winter into spring.
Best practice monitoring requires a WormTest3, also known as a worm egg count (WEC) test, of a mob every 4-6 weeks during the barber’s pole worm season or after a combination of high temperatures and rainfall. Ideally, larval differentiation should be conducted to confirm that barber’s pole worms are present. WormTest results will help to identify the ideal drenching time. Thresholds for treatment vary across Australia and Wormboss3 can provide specific guidance for your region.
Drench resistance is common in barber’s pole worms in sheep but the pattern and degree of resistance vary by region, and even by farm. It is important to understand the resistance profile of your farm by conducting regular DrenchChecks3 (WormTest up to 10 days before and at 14 days after drenching) to assess drench effectiveness and by conducting a full DrenchTest3 (examines each drench’s effectiveness for each worm type present and is the most accurate way to test for drench resistance) every 2-3 years to identify the most effective actives to use.
All drench treatments should be conducted using products to which the specific worm population is susceptible, based on the testing described above. A range of narrow, medium and broad-spectrum products are available. Closantel-based products, like AVOMEC® Duel, with sustained activity against barber’s pole worm, offer a good treatment option, particularly when the barber’s pole challenge is severe. See product label for full claim details and directions for use.
Management of barber’s pole worm is challenging, however, with the right monitoring, testing and treatment plan the impact on your mob can be minimised. Speak to your local animal health advisor to determine the most appropriate testing and treatment plan for your area.