What is Barber’s Pole Worm?
The barber’s pole worm (Haemonchus contortus) is a blood-sucking roundworm of sheep and goats, with minor crossover into cattle. The worm gets its name from the ‘Barber-pole’ colouration of the female worm as its blood-filled intestine and uterus intertwine. Two to three centimetre long adult female worms can be easily seen on a fresh post-mortem in the stomach contents of an affected sheep.
According to Dr Paul Beltz (Agriculture Victoria senior veterinary officer), barber’s pole worms favour warm, humid conditions but rarely causes disease as the Victorian climate doesn’t normally favour it reproducing rapidly. However, issues have arisen with the recent rainfall and moisture during the summer and early autumn months.
Its lifecycle is like other roundworms. The eggs are passed in an animal’s faeces, they hatch, develop to an infectious stage, are eaten by a susceptible animal and develop into an adult worm in the animal’s fourth stomach.
A barber’s pole female can lay 5,000-10,000 eggs a day, which is around 50-300 times more than the winter scour worm. These eggs are comparatively fragile so they require specific warm moist temperatures to develop into infective larvae. When daily maximum temperatures of at least 16-18ºC and soil moisture is high or 10-15mLs of rain occurs within five days of eggs being deposited, eggs can develop as quick as 4-6 days. Because of this, there is little development between May and early September in most parts of Victoria.
In autumn, winter and early spring, it may take around 6 months for 90% of barber’s pole worm larvae to die, but in summer this time can be reduced to 6 weeks of hot dry weather.
Worm burdens caused by barber’s pole worm can build up relatively quickly in affected sheep due to the fact they have a relatively short life cycle and produce many eggs compared with other roundworms.
Heavily infected sheep can lose up to 250mL of blood (5-10% blood volume) per day. The biggest impact barber’s pole worm has is death of affected sheep. There is often little in the way of sub-clinical production effects.
Barber’s pole worm larvae will start to consume blood before they are able to lay eggs so in situations with severe pasture contamination, sheep may die before egg counts rise and this can occur soon after drenching.
Animals in early stages of infection show minimal clinical signs. As blood loss continues, the following will develop:
- “Bottle jaw”
- Collapsing or dropping back from the mob when driven
- Extremely pale inner eyelids and gums
In infections of just barber’s pole worm, there is usually no scouring but conditions that are ideal for barber’s pole worm are often also ideal for scour worms so chronic heavy infections of scour worms can also cause “bottle jaw” and anaemia.
Clinical disease is primarily seen in weaners and lambing ewes and is more pronounced with poor nutrition.
A tentative diagnosis of barber’s pole worm can often be made based on previous history, clinical signs and very high worm egg counts (in the thousands). A diagnosis can be made based on clinical signs and a worm egg count.
Poo samples will need to be collected and sent to a lab for larval differentiation/speciation or PCR test. These tests identify different species of worms contributing to the egg count and will give you a percentage of each type of worm present.
Samples can be collected from the rectum of animals in a race, or in the paddock. To collect dung samples in the paddock, muster a large number of the mob to a clean corner of a paddock for 10 minutes and then let them drift away quietly. Young animals, such as weaners, are an important group to sample because they tend to be quite vulnerable to worms. However, it may be necessary to sample more than one mob.
Be aware though that since barber’s pole worms are such prolific egg layers so worm egg counts reach normal drench trigger points even with a low number of the barber’s pole worm, which may lead to unnecessary drenching.
Treatment of acute cases will require knowing what species of worm you’re dealing with and whether there is a “safe paddock” to move the affected sheep to after drenching.
…[treatment of chronic cases?]
If a “safe paddock” is available, drench onto that pasture with a short acting product like napthalaphos. If no “safe paddock” is available, a longer acting product such as closantel, may need to be used to prevent immediate re-infection.
Barber’s pole worms are notorious for developing drench resistance quickly. It is worth checking if your drench has worked by doing another worm egg count – the timing will depend on which drench you use.
For example, closantel is a narrow spectrum drench so it will protect against barber’s pole worms for 28 days. While oral moxidectin will work for 2 weeks. Conversely, injectable moxidectin will give 21 days and long acting moxidectin injections will provide 91 days of protection.
…[how to know what drench to use]
It is important to prevent the introduction of resistant barber’s pole worms onto your property. For all sheep brought onto your property, you should follow the standard protocol of:
- Use a 4-way drench
- Empty out in yards on arrival
- Grazing a “wormy paddock”
- Check the drench has worked 10-14 days after arrival
Grazing strategies can be very successful in reducing the worm burden on farm and reliance on chemical control. High intensity rotational grazing, preparing low-risk paddocks through smart grazing or strategic use of medium to long-acting products, are highly effective at reducing pasture contamination.
- Checking a mob of sheep or goats for worms with a WormTest
- Barber’s pole worm in cattle
- Barber’s pole worm in sheep/goats
- Worm egg counting
- List of WEC testing labs 2023
- General advice for naphthalophos
- Rametin® no longer produced
- FAMACHA system to slow drench resistance
Central West Local Land Services – Barber’s pole worm PDF
For further information, please contact the VFF Livestock Group on 1300 882 833 or by email [email protected]
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