An Armidale-based company has developed a replacement drug, called Nitro-fluke. Vet Matt Ball has spent the last week touring the region shopping it around. At a meeting on Monday, he explained the value of the new product to about 50 farmers in Glen Innes.

Fluke are a painful parasite that live within snails and are transferred to cattle, sheep, many other agricultural animals, and potentially people. Symptoms include weight loss, fever and abdominal pain.

In the 80s, Armidale scientist Joe Boray developed a "wonder drug", Triclabendazol; it kills young fluke before they cause damage, it has no painful or deadly side effects, and for many decades it was unbeatable. It allowed producers to spread cattle into fluke-infested areas without fear of infection.

But for about 10 years, the parasite has been gradually building immunity to the drug, which is the only comprehensive treatment available.

Jane Kelley, a PhD candidate from La Trobe university, said the attitude among researchers through the 90s was "that problem has been solved". Immune live fluke now cost farmers in excess of an estimated $50-90 million a year, but it's likely much more.

Nowadays there is a fail rate of above 20 per cent, thought the total number isn't known. That means the immunity buildup will speed up because more fluke surviving the initial dose means more to build an immunity.

Nitro-fluke was introduced to the market in 2010, but Mr Ball said they still need to raise awareness of problems with resistance among farmers. The drug isn't a new chemical, it's a combination of a number of existing treatments into a much more effective one.

The new drug could even be a boon for the third world, where Triclabendazol has long been used to treat liver fluke in people.