Calgary researchers have helped sequence the genome of the barber’s pole worm, and that will aid efforts to control the intestinal parasite that affects goats and sheep.
“Without the actual genome sequence, we can never get to the applied ends of what we’re trying to achieve,” said John Lilleard of the University of Calgary’s Faculty of Veterinary Medicine.
The sequencing was an international effort and took five years to complete. But now researchers have a powerful tool for developing new tests and treatments to combat parasites.
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“Without the actual genome sequence, we can never get to the applied ends of what we’re trying to achieve,” said Lilleard, who along with U of C colleague James Wasmuth was on the sequencing team.
The barber’s pole worm is closely related to many other livestock parasites, so learning more about it will help researchers fight other parasites as well. The parasite has been found in cattle, but only rarely.
Ivermectin is one of the drugs used to combat the barber’s pole worm, but the parasite is developing resistance, said Wasmuth.
“We want to understand how this parasite develops drug resistance because it seems to be very good at doing that,” he said. “We have a team in Calgary as well as collaborators in Glasgow and in Cambridge and quite a few places around the world who will be looking at the genes in this genome and asking a number of questions including how it evolves drug resistance and how the parasite survives so well in the host,” he said.
“One of the things we need is a better test for diagnostic resistance,” said Lilleard. “Another thing we need to know is how resistance is emerging and how common it is in different parts of the industry. At the moment, we have very little ability to see what the drug resistance situation is.”
Life cycle
The barber’s pole worm sucks blood from the true stomach of sheep or goats and the animals die from blood loss. The parasite lives in the stomach of infected sheep, becoming active when pregnant ewes are close to lambing. Eggs are passed in an animal’s fecal matter and then eaten by the other sheep in the pasture. Once ingested, larvae develop into adults inside the stomach. The situation is exacerbated because larvae have a dormant stage, and their life cycle is fairly complicated. The first sign of an infestation is often the death of lambs.
Barber’s pole worm is a serious problem in Alberta, especially in the Barrhead and Westlock area, said Kathy Parker, a veterinarian in Three Hills. Producers who want to combat the parasite need to rely on management practices, including pasture rotations and strategic worming protocols.
“It’s a very planned management model. It all has to be done at the right time with the right product, and then you have success in managing it,” said Parker. “Producers who are diligent in their management and committed to the parasite control strategy have high degrees of success.”
Producers can reduce pharmaceutical use by learning about the life cycle of the parasite and creating an effective pasture management strategy. The parasites are most vulnerable in the larval state, so it’s generally best to worm the ewes or does when they are close to lambing or kidding.
“If we can limit the parasite at that critical stage, then that helps,” said Parker.
