It is most commonly found in all sheep production districts in Queensland and the northern half of NSW where summer rainfall is common or dominant. Barber's pole worm is less of a problem in the winter rainfall areas of Australia, but localised pockets exist in all states. It is a bloodsucker and can have a severe impact on all classes of sheep.

Barber's pole worms are quite large (20 to 30mm) and clearly visible in the 4th stomach or abomasum. Adult females have a characteristic barbers pole appearance like red and white twisted wire. The male is smaller (around 15mm).

Barbers pole worm

This image was kindly supplied by Associate Professor Nick Sangster, University of Sydney

Lancet on Barbers pole head

Photo by J.A. van Wyk, Faculty of Veterinary Science, University of Pretoria and Onderstepoort Veterinary Institute, South Africa

Find out more about barber's pole worm :

• Life cycle
• Location in the sheep
• Effects on the sheep
• Diagnosing barber's pole worm
• Treatment

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 Barbers pole life cycle

Female barber's pole are prodigious egg layers and can lay up to 10,000 eggs per day. The adult female in the 4^th stomach (abomasum) lays eggs, which are passed out in the dung.

If the weather is warm and moist the eggs hatch into first stage larvae (L1). These moult or shed their skin (cuticle) to become 2^nd stage larvae (L2). Second stage larvae (L2) undergo an incomplete moult to become 3^rd stage larvae (L3) which are the infective larvae.

L3 larvae retain the old L2 cuticle, which provides a protective sheath and nutrients until the larvae are ingested by a sheep. However this cuticle prevents L3 larvae from feeding on bacteria.

All larval stages (except L3s) feed on bacteria in the dung pellet until they either die or escape from the dung pellet onto the pastures.

Under ideal environmental conditions, development from egg to L3 takes around seven days, but can be as long as five weeks if conditions depending on warmth and moisture. Heavy dews and rain release the L3 from the dung pellet onto the pasture. L3 larvae increase the chance of being ingested by sheep by responding to light and temperature.

As the pasture is warmed by sunlight and in the presence of moisture (dew/rain) the L3 migrate up the grass blades where they are most likely to be eaten. On cold nights they move down to the base of the grass. When the L3 are ingested, compounds in the gut of the sheep stimulate the larvae to rapidly (usually within 30 minutes) complete the second moult (exsheathment) and start moving towards the 4^th stomach (abomasum).

On the way they moult a third time and arrive in the abomasum as an immature worm. When the larvae mature, they mate and the cycle starts all over again.

It takes around 21 - 28 days from when a sheep ingests the larvae to when worm eggs appear in dung samples.  It is important to remember this for 2 reasons:

• If the sheep are treated with a fully effective short acting drench, they can be used to "clean" paddocks for weaners (smart grazing) for the 21 - 28 day period without fear of recontaminating the paddock.
• If the sheep are tested for worms using a worm egg count during the 21 - 28 day period, you may think that the sheep are free of worms when, in fact, they could have a considerable burden of larvae.  If you think the sheep could be picking up worms after drenching, tests at about 4 - 6 weeks when egg laying has commenced and you will have a much better idea of the rapidity and scale of the reinfection.

Naturally, if a sustained action drench was used, the period from treatment to eggs in the dung is longer, being the length of action of the drench plus 21 - 28 days.

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 Location of barbers pole worm in the sheep

Barbers pole worms are located in the 4^th stomach or abomasum of the sheep.

Graphic kindly supplied by Associate Professor Nick Sangster, University of Sydney.

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 Effects on the sheep

Barbers pole worms are voracious blood feeders and suck blood from the lining of the stomach, causing anaemia.

Feeding by 4^th stage and adults may remove 0.05ml of blood per worm. A burden of 1000 worms may remove 50ml of blood per day from the sheep.

Sheep with heavy infections of barbers pole worms lack stamina, have pale gums and conjunctiva, and may also have bottle-jaw or constipation.

If sheep are showing these signs, the faecal worm egg count is invariably very high, often over 10,000 eggs per gram (epg). Weight gains and wool growth can be reduced to zero (or even weight loss) and wool tensile strength can often be reduced to less than 20N/Kt.

Sheep with lighter burdens (say 500 to 2000 epg) will have reduced wool growth, weight gains, milk production and growth. This reduced productivity increases with the worm egg count.

For example, a subclinical (no visible signs of worms) infestation can reduce weight gains by 30%, wool growth by 10% and milk production by 30%.

If present in large numbers, barbers pole worms can kill sheep. In these animals large, red masses of worms are clearly visible in the stomach. The stomach contents are often brown because of bleeding from the stomach lining and the lining has pin-point blood spots on it. The blood of the sheep is watery due to anaemia.

The unseen impact on sheep productivity is much more severe. In sheep with lighter infections worms are present in the stomach, but the lining of the stomach looks normal.

Bottlejaw in sheep

This image was kindly supplied by Dr R Woodgate, Western Australian Department of Agriculture

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 Diagnosing barbers pole worm

The only accurate way to diagnose barbers pole worm infestations before productivity losses have occurred is to conduct a worm egg count and larval culture and identification.

Conducting worm egg counts diagnoses infestations before they cause productivity losses and allows producers to plan treatment rather than react to a crisis.

To accurately identify the worm species present, the sheep dung sent to a laboratory is processed and put in an incubator to hatch the eggs. The resulting larvae are identified.

By knowing the worm egg count and the species present, a producer can make the best choice of drench for the situation.

Traditionally, sheep producers relied on visual signs of barbers pole infestation such as pale gums, eyes and skin (anaemia) and 'bottle jaw' (oedema).

The problem with this diagnostic method was that, by the time the sheep showed these signs, the infestation was very high and significant productivity losses had already occurred. Often many deaths occurred.

Producers who conduct regular worm egg counts, know the species present and the drench resistance status of their properties have healthier sheep and drench less.

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 Treatment of barbers pole worm

There are many options to treat barbers pole worm:

• Narrow spectrum – treats only barbers pole and maybe a few others
• Mid-spectrum – Treats barbers pole and black scour worm.
• Broad spectrum – treats all major worm species
• Long acting – kills resident worms and protects against incoming larvae for varying periods (read label carefully). Some of these are also narrow spectrum.
• Short acting – kills resident worms and rapidly disappears from the animal. They usually broad spectrum.
• Combinations - usually broad spectrum and short acting, but some have sustained action against barbers pole worm.

When choosing a drench, you will need to consider:

• What is the resistance status for the various worms on your property?
• Are there other species present with the barbers pole worms?
• Is a long acting drench really required – this is often influenced by the risk of reinfection and the likely weather outlook.

Knowing the worm egg count, the species present and the resistance status of the various worms allows you to choose the best drench for the situation.