Barber's Pole Worm (Haemonchus contortus)

The blood-sucking parasite barber’s pole worm is quite dangerous for sheep, causing an infection known as haemonchosis which, because of its blood-sucking activity, can result in anything from anaemia and lethargy to death.

The pest is most commonly found in areas of Australia that are dominated by summer rainfall, such as Queensland and parts of northern NSW. While it’s less problematic in cooler parts of the country that tend to experience heavier winter rainfalls, there’s an ever increasing number of outbreaks in the southern states.

Skip to:
Overview
Signs
Diagnosis
Prevention
Treatment
Chemvet Products

Overview of Barber’s Pole Worm

The female worm bears the pink and white patterning that resembles a barber’s pole and gives the Haemonchus contortus its common name. The male worm is pale pink, and grows to a shorter length (15mm) than the female (20-30mm). Each adult worm sucks 0.5mL of blood from the animal, per day. Therefore large numbers of barber’s pole worms can cause sheep to become anaemic very quickly.

Life Cycle

The life cycle of the barber’s pole worm is shown in the picture above. The whole cycle takes approximately 21 days, however there are some strains of ‘high achieving’ barber’s pole worms that can complete the life cycle in 19 days when environmental conditions are optimal.

Favoured Environmental Conditions/Risk Factors

Barber’s pole worms are most commonly found in areas of Australia that are dominated by summer rainfall, such as Queensland and parts of northern NSW. They thrive when temperatures are between 18 – 33˚C and there is between 40-80% moisture content in the ground. This may be from rainfall, heavy dew or irrigation.

While it’s less problematic in cooler parts of the country that tend to experience heavier winter rainfalls, no state or territory is completely immune from these parasites. The following graphs show the risk periods for different rainfall areas in Australia.

Signs of Barber’s Pole Worm

Each adult worm sucks 0.5mL of blood from the animal, per day. Therefore, signs of a barber’s pole infection include:

Unable to gain weight, not scouring
Anaemia – pale gums, eye membranes, skin
Lethargy and collapse when getting herded
Rapid loss of condition
Bottle jaw
Death (especially with rapid onset infections)

Normal (left) vs anaemic (right) gums in sheep.

Barber’s pole worms do not make the sheep scour, so it’s important to look for other signs if you have the worm in your area and under the right conditions. Especially during high risk periods.

Diagnosis

Beyond observing the signs listed above, diagnosing Barber’s Pole in a live sheep involves a worm egg count and larval culture. It can also be conducted post-mortem by locating the abomasum (4^th stomach) carefully checking for the presence of the worms (see picture below).

An interesting fact about the female barber’s pole worm is that they can lay up to 10,000 eggs per day. This means that when conducting worm tests, the counts will be a lot higher than those of a severe scour worm infection. So, if you’ve got a faecal egg count result in the thousands, and your sheep aren’t scouring, it’s a very good indicator that the infection may include some barber’s pole worms. This is one way to infer a barber’s pole diagnosis, but the only way to confirm it is to complete a larval culture after the egg count to identify the worm species.

Preventing Barber’s Pole Worm

Prevention involves employing one or more of the following methods.

Preparing low worm paddocks

This is the most effective way of preventing severe barber’s pole infections. The aim of this method is to prevent pasture contamination for an extended period of time, while existing larvae population die off. The paraboss graph below, shows how long it takes for barber’s pole larvae to die off under different temperatures when spelling a paddock.

This can also be achieved by grazing the pasture with cattle (sheep and cattle don’t share the same worms) or by grazing the pasture with sheep that have been treated with a long acting drench. These options ‘mop up’ the infective larvae off the pasture without recontamination.

Monitoring worm egg counts diligently

The aim of monitoring worm egg counts (worm testing) is to catch potential barber’s pole problems as they develop and to treat early to prevent severe pasture contamination. In summer rainfall regions, check worm eggs counts by mid-September at the latest. In high risk areas, worm testing can be done as often as every 4-6 weeks. This is especially important for weaners going through high risk periods. Expert interpretation of worm test results is key for getting your money’s worth with testing.

Other strategic times to conduct worm testing include:

Pre-lambing
Late January if drenching was not done in October/November
Late February if drenching was done in October/November
Weaners from weaning to shearing: every 4-6 weeks (summer) or 6-8 weeks (winter) after a drench.

If you would like to get some worm test kits to start a testing regime, give us a call on 1800 243 683. Chemvet provides advice, free of charge, once the results come in and can help you develop an initial and/or ongoing parasite management plan.

Vaccinating with Barbervax

The final prevention method is vaccinating with Barbervax. This method requires preparation and ongoing commitment throughout the barber’s pole season. The following table is taken from the Wormboss website and outlines an example Barbervax vaccination schedule.

	Vaccinated the previous year	Not previously vaccinated
Lambs or Hoggets	V1: November/December (earlier if spring is wet) V2-V5: after V1, give at 6-weekly intervals while protection is required.	V1: lambs at marking; hoggets during October V2: 3-4 weeks after V1 V3: 3-4 weeks after V2 V4-V6: after V3, give at 6-weekly intervals while protection is required.
Breeding ewes (assumes spring lambing)	V1: 1-2 weeks pre-lambing V2: lamb marking V3-V6: after V2, give at 6-weekly intervals while protection is required.	V1: 8-9 weeks pre-lambing V2: 4-5 weeks pre-lambing V3: 1-2 weeks pre-lambing V4: lamb marking V5 onwards: after V4, give at 6-weekly intervals while protection is required.

V= vaccination, the number (1-6) refers to first, second (and so on) vaccination in the series given in the one barber’s pole worm season.

Note that it is important to also adhere to routine drenching and worm testing regimes while using Barbervax. This is not a product supplied by Chemvet this section is purely informative.

Treating Barber’s Pole Worm

Treating barber’s pole involves administering an effective drench. Depending on the level of infection, this may involve more than one treatment or the use of a long acting drench.

Most broad spectrum drench actives/chemicals are effective against susceptible barber’s pole worms. These include:

Macrocyclic lactones (abamectin, moxidectin, ivermectin)
Benzimidazoles (albendazole, oxfendazole)
Levamisole
Salicylanilide (closantel)
Amino-acetonitrile derivative (monepantel)
Spiroindole (derquantel)

The best drenches for barber’s pole are multi-active drenches that include 3 or more of the active chemicals in the list above. For example, Vetmec LV and Vetmec Dual combine to make a triple active drench. Closantel, monepantel and derquantel are newer active ingredients that you can add to the mix if resistance is building to the older chemicals. These worms are extremely clever at developing resistance. The severity of resistance, and to what drench group is resistant to, is different for every property so it’s important to complete periodic drench checks or chemical resistance testing. A drench check involves worm testing before you drench, then testing again 10-14 days after you drench and comparing the two results to find a % reduction.

If you have a severe barber’s pole infection (confirmed by a worm test), there are some drench strategies that will kill the worms in the sheep, and also reduce the number of larvae on the pasture.

Strategy 1: Drench + 18 Days + Drench Again

This strategy involves drenching with an effective short acting oral drench once, then again 18 days later, and again in another 18 days (repeat if required). This sequence kills the first lot of worms off, then the sheep act like ‘vacuum cleaners’ picking more infective larvae off the pastures, and the second drench kills the next lot of worms before they start laying eggs, and so on. Doing so means that less eggs are produced and therefore results in fewer worms in the environment.

Strategy 2: Long-Acting Drench

This strategy works in a similar way to the one above, except involves giving one long-acting injection with a multi-active oral primer drench. Long acting drenches, such as Vetmec Moxiguard, will kill incoming barber’s pole worms for up to 4 months. Please note it is vital that the multi-active oral drench is given at the same time to ensure that protection period. If a primer drench is not given alongside a long acting drench, the protection period can drop to as short as 3 weeks.

If you have any questions about anything you’ve read about barber’s pole worm, or any other parasites, get in touch with one of Chemvet’s expert parasite advisors to help you develop the right parasite management plan for your stock and your property. Give us a call on 1800 243 683 or Contact Us through the website.