Wild turkeys brought along a potentially deadly pathogen when they were reintroduced into Maine in the 1980s. That could be bad news for flocks of domestic turkeys and other poultry in the state that already are on watch for avian flu.
Stephanie Shea, associate director and diagnostician at the Northeast Plant Diagnostic Network at the University of Maine, has been researching the Lymphoproliferative virus — LPDV for short — with a team of fellow scientists in Maine’s wild turkey flocks.
What they found was that 59 percent of the nearly 700 turkeys tested for LPDV over a three-year period ending in 2020 tested positive for the disease.
With the populations and range of LPDV-infected wild turkeys expanding in the Northeast, the risk of infecting their domestic counterparts could increase. So far, there is no indication that is happening and it has not yet shown up in any domestic poultry flocks in Maine.
While symptoms of LVPD include tumors, lesions, lack of coordination and lethargy, all of the turkeys testing positive in the Maine study showed no outward signs of the disease.
“Every single one of them we tested were asymptomatic but more than half of them had the disease,” Shea said. “Could this pathogen that is obviously circulating have subclinical effects impacting [wild turkey] reproduction and survival?”
Equally important to domestic fowl is whether the pathogen could jump from the wild birds to flocks of chickens, turkeys, geese or ducks on farms or homesteads around the state.
Humans cannot get LPDV and infected birds are safe to eat. In fact, 75 percent of the wild turkeys in Shea’s study that were harvested by hunters tested positive for the disease.
The only places globally where wild turkeys infected domestic turkeys is in Israel and Europe, Shea said. In domestic turkey populations, LPDV is transmitted through direct contact between infected birds. It’s not known if that is the case for wild turkey disease transmission.
“That is some of the motivation for our work,” Shea said. “Another motivation was how fast the wild turkey population grew in Maine.”
Turkeys are native to North America. By the mid-1800s, they had been hunted to extinction in New England by European colonizers.
In the 1980s, wild turkeys were reintroduced in Maine from birds captured in Connecticut and Vermont. In four decades, the 100-member original flock has grown to 60,000 birds spread into all 16 Maine counties.
The biggest impact LPDV seems to be having on Maine’s wild turkeys is in the nest.
“We did find LPDV does impact the number of eggs laid by an infected hen,” Shea said. “They generally have a low nesting success to begin with.”
The decrease in eggs among infected birds could be mitigated by a mother turkey having better success with fewer chicks to raise, Shea said.
The study also showed a higher infection rate among female wild turkeys in general and among both females and males sampled in the spring rather than in winter. Juvenile turkeys living in forested areas had a higher rate of infection than those living near farms.
These differences could be factors of physiology, foraging behaviors, location, flock movements over time and mating behaviors, according to Shea.
Early last year, the highly contagious virus avian influenza H5N1 was detected for the first time in Maine in both wild birds and domestic flocks. It has since spread to six counties and led to the deaths of more than 600 domestic poultry birds, both from the virus itself and from euthanization of a remaining flock.
She hopes the research can help inform management strategies, such as harvest, relocating existing flocks and support any future investigations into the possibility of disease transmission between wild turkeys and other fauna.
“Our findings highlight patterns of LPDV infection in Maine’s wild turkey population,” She said. “This can help us to predict location, timing and individuals affected and is useful for monitoring wild turkey health.”
