Barber’s pole worm (Haemonchus contortus) is the most important parasite of sheep in the summer rainfall areas of Australia.
Therefore, it is not surprising that we are seeing outbreaks of disease due to barber’s pole worm with the warm, moist conditions that we have recently experienced.
Adult barber’s pole worms live in the abomasum (fourth stomach) of sheep.
The mature female worms are visible to the naked eye.
The gut of the worm is red, as it is full of blood. Wound around the gut is the white ovary, packed with hundreds of eggs. This red and white spiral effect gives the worm its name as it looks like the classic barber’s pole.
The adult female worms are prolific egg producers leading rapidly to a heavy pasture contamination.
Recently we have seen faecal egg counts in the tens of thousands due to barber’s pole worm.
During warm, moist conditions these eggs hatch into larvae and are eaten by sheep during grazing.
Given their prolific production, worm numbers can build up rapidly.
Like other internal parasites, barber’s pole worms mainly affect weaners and lactating ewes.
Barber’s pole worms feed by sucking blood leading to anaemia and 'bottle jaw' but not necessarily weight loss or diarrhoea.
Just 1000 adult barber’s pole worms can remove 50ml of blood from a sheep per day.
Therefore, barber’s pole worm outbreaks can lead to high mortalities in a short space of time.
Barber’s pole worms can be detected at post-mortem, or in live animals by a faecal egg count.
As with other internal parasites, drench resistance to barber’s pole worm is becoming increasingly common.
Unfortunately, losses due to Barber’s Pole worm are currently being reported in spite of recent drenching.
For further information, contact your local veterinarian or Agriculture Victoria veterinary or animal health officer, or in NSW your Local Land Services.
Dr Jeff Cave is a senior veterinary officer with Agriculture Victoria.