University of Maine research tackles issue of lungworm in moose

ORONO, Maine — In his tenure as the state’s top moose biologist, Lee Kantar has spent a lot of time doing “disease surveillance” on the state’s iconic land mammal.

But a recent University of Maine study of a contrastingly uncharismatic critter — the lowly lungworm — has begun to look at the worm’s role in moose mortality, and researchers have learned that even the subject of their study had been tentatively misidentified for years.

In short, recent UMaine graduate Darryl Ann Girardin and Anne Lichtenwalner, a veterinarian and assistant professor who serves as director of the UMaine Animal Health Laboratory, have found that there’s a new worm in town.

The ramifications of that discovery are yet-to-be learned, but worth considering for a simple reason: DNA tests have determined that the kind of worm that exists in Maine moose most closely matches one that’s typically found in red deer and fallow deer, not moose. And any time a parasite is found in an unexpected host, scientists get concerned.

“What happens when a parasite gets into a new species, a new host species?” Lichtenwalner said. “They’re hitchhikers, and now they’re suddenly adapting what they do to a new food source — us [in cases of swine or avian flu], or the moose in this case — they cause more pathogenicity. They tend to cause more of a ruckus. The person, the animal, the swine, the bird, whatever, tends to get sicker.”

Kantar said the DIF&W has known for years that lungworm existed in moose. The question they had: Is that presence of worms actually “the nail in the coffin that killed the moose?”

His department has also been studying the role of winter ticks in moose mortality. Many moose reported dead were found to have infestations of both ticks and lungworms. About two years ago, Kantar said, the department started to get more curious about lungworms and wondered how important a role they played in deer deaths.

“If you’re a calf moose and you’ve got a winter tick load, and on top of that, you have diminished lung capacity because you’re riddled with lungworms, then that’s probably the nail in the coffin,” Kantar said. “That combination.”

Another UMaine student, Jana Drury, began lungworm research two years ago. Last year, Girardin got involved with the study as her senior project, and began trying to discover which species actually existed in Maine’s moose.

“[During moose season] we went out to gut piles and flushed lungs for lungworm in those gut piles, which was really interesting,” the Presque Isle native said.

Then the hard work of analyzing her samples began.

Much of the lab work was done under the guidance of graduate student Sarah Barker, who walked Girardin through the complex task of DNA sampling, polymerase chain reactions and cloning the DNA into a bacterial vector so that the group had a large enough concentration of the sequences they wanted to isolate.

The goal: Identify the worm by comparing it to known samples of other worms. In particular, was this lungworm dictyocaulus viviparus, a worm that has commonly been found in moose, as biologists had long assumed?

It wasn’t.

“The islets that our lungworm is similar to are most commonly found in lungworms that do affect moose, but most commonly affect red deer and fallow deer in Sweden,” Girardin said. “They were also very similar to islets found in red deer in New Zealand.”

And what does that mean? The jury’s still out.

“There’s a possibility that these lungworms could have been a deer lungworm that, I don’t know how recently, could have jumped into the host species of moose and that’s why we’re seeing all [these ill effects] in moose,” Girardin said.

Simply eliminating dictyocaulus viviparus as the worm that exists in Maine moose was of interest to many scientists, Lichtenwalner said.

“We’re saying, ‘We don’t know exactly what kind of lungworm this is. But we do know it’s not dictyocaulus viviparus,’ which is enough of a story to tell the scientific community,” Lichtenwalner said. “They’re interested.”

Interested enough, in fact, to invite Girardin to an October conference to present her findings — formerly a senior project — to the nation’s best: She’ll attend the annual conference of the American Association of Veterinary Lab Diagnosticians in Greensboro, N.C., from Oct. 20-22 and do just that.

“This is a big deal,” her proud mentor, Lichtenwalner said.

As for implications of their findings — for example, should Maine’s licensed deer farms fall under further scrutiny to make sure that parasites are not allowed to spread to other animals — Lichtenwalner chose her words carefully.

“Lee [Kantar] has been very careful to say, ‘Let’s not jump in hastily,’” Lichtenwalner said. “But we do think that what you’re talking about is one of the possibilities, and that’s nothing totally new. If the IF&W wants to look at this more carefully, it may have implications around biosecurity around deer farms.”

Lichtenwalner also said she has nothing against the presence of exotic animals or deer farms in Maine. Instead, she said that thinking about prudent management of all kinds of agricultural facilities and resulting biosecurity issues is good for all the state’s animals.

Kantar said the big-picture questions haven’t even been considered yet.

“We haven’t really gone to the next step of ‘what does this mean in the scheme of things in the state,’” Kantar said.

Kantar also praised the work of Lichtenwalner and the UMaine team.

“It’s fantastic to have a vet who you can work on with these issues, because most biologists are trained as field biologists to recognize some level of disease and pathology, but you really need much finer training, and you need to have lab analysis of things that are going on,” Kantar said.