Novel new research into animal parasites

Dr Dave Leathwick

A new AgResearch science project, believed to be the first of its kind in the world, will investigate the potential of tricking animal parasite larvae to shed their protective shell (a process called ‘exsheathing’) on pasture so they die rather than being ingested by animals.

This work is possible with the announcement of two year, $1.15 million funding by the Ministry of Business, Innovation and Employment (MBIE) ‘Smart ideas’ programme.

Internal parasites currently cost New Zealand sheep, beef and deer farmers $700M each year in lost production and treatments but if it was successful, this project would provide benefits to those farmers as well as owners of horses, alpaca and other non-commercial livestock.

Principal scientist Dave Leathwick, who leads the team of AgResearch scientists, says the idea is to stimulate nematode parasite larvae to exsheath while still on the pasture, rather than in the host. If they can do this the larvae will rapidly die through being “in the wrong place at the wrong time”.

An effective treatment capable of killing parasite larvae on pasture would have many and wide-ranging benefits for farmers and other owners of livestock. For example, it would greatly improve the ability of sheep and beef farmers to prevent the importation of resistant worms onto their farm with bought-in stock.

But the benefits would also have huge implications for other farming operations. For example, parasites are a major issue for goat milking operations because of issues around milk withholding periods if normal drenches are used. An effective paddock treatment for worm larvae would reduce or even eliminate the need for these farmers to drench their milking goats to control worms.

Dr Leathwick says the product could also benefit farmers around the world practicing intensive pastoral agriculture by reducing dependence on animal health remedies – and associated labour requirements as well as significant financial benefits to the New Zealand company owning any Intellectual Property.

“The aim of the study is to find triggers that will stimulate larvae to exsheath outside the host. While a novel concept the team realises this will not be an easy task. The exciting thing about this project is the team of great people we have brought together. We have put together a team which brings together capability in Chemistry, Microbiology, Soil biology as well as Parasitology. I think if anyone is going to work this out it will be a team like this.”

Dr Leathwick says the concept of triggering larvae to exsheath outside the host is logical, but it appears from the literature that no-one has previously investigated the possibility. The major focus of R&D over previous decades has been on targeting control through the animal. Sheep and cattle farmers in New Zealand spend around $150M annually on anthelmintics to try and control parasites and there is also growing concern at increasing resistance to many of these animal remedies.