Three Itasca County ruffed grouse that appeared sick have tested positive for a mosquito-borne virus called eastern equine encephalitis (EEE), marking the first time the virus has been confirmed to cause illness in a Minnesota wild animal.
“Now that we’ve found the EEE
virus in Minnesota grouse, we will continue to monitor grouse
populations for signs of the disease,” said Michelle Carstensen,
wildlife health program leader for the Minnesota Department of Natural
Resources. “It’s too soon to say how widespread the EEE virus might be
in grouse populations because we only have one year of grouse sampling
results from 2018.”
EEE is a rare illness in humans. People bitten
by infected mosquitoes seldom develop any symptoms but the virus can be
serious if they do.
The hunters who harvested the grouse brought
them to DNR staff in late October after they noticed abnormal behavior
in the birds – they didn’t or couldn’t fly away. When field dressing the
birds, the hunters also noticed reduced muscle mass.
submitted samples from the birds to the University of Minnesota’s
Veterinary Diagnostic Laboratory (VDL). Tests concluded two and possibly
a third were infected with EEE virus. The third grouse - suspected of
having the virus, also had inflammation in the brain, providing further
evidence that it likely also suffered from EEE. All birds tested
negative for West Nile virus.
“It is rare for us to find EEE in
Minnesota, but this year we’ve diagnosed the virus in these grouse and a
horse,” said the VDL’s Dr. Arno Wuenschmann. “I initially suspected
that West Nile virus caused the encephalitis but molecular tests
conducted on the grouse in collaboration with the Animal Health
Diagnostic Center at Cornell University proved EEE virus was to blame.”
EEE virus is typically found in the eastern United States and along the
Gulf Coast but also has been found in other states, including Michigan
Prior to this discovery, the DNR had confirmed that
wolves and moose in northeastern Minnesota had been exposed to the
virus but never found animals of either species sick with the disease.
2018, the DNR began asking hunters to submit grouse samples for West
Nile virus testing. Samples collected the first year showed 12 percent
of the birds had been exposed to West Nile virus but none had been
exposed to EEE.
“We’ll keep testing samples that hunters submit
for both viruses,” Carstensen said. “Hunters who harvest sick grouse
also can help us by contacting a nearby DNR area wildlife office so they can submit those samples for testing, too.”
with any wild game, care should be used when processing the animal to
avoid cuts that could cause potential infection. Any game that appears
abnormal – either in the field or after dressing – should not be
consumed. Hunters with questions about what they harvest can contact a
nearby DNR area wildlife office .
Grouse sampling information can be found on the DNR website .
Read the full MN DNR article.