A horse in Somerset County is the third domesticated animal in Maine this year to test positive for Eastern Equine Encephalitis, or EEE.
Maine CDC director Dr. Puthiery Va said two emus have also tested positive for the mosquito-borne virus.
"What we're seeing across the region, actually — it's not just in Maine — is that we're seeing activity earlier and we're seeing it go longer," Va said. "Because it's just warmer and the environment is just perfect for mosquito breeding and the mosquito population."
Va said there have been no human cases of EEE so far this year in Maine.
The disease is often fatal in horses. In humans, it's fatal in about a third of cases.
It often starts with flu-like symptoms but it can progress to brain swelling and meningitis.
State officials urge the public to take precautions to wear insect repellent, long sleeves and pants, and drain artificial sources of water, where mosquitoes may lay eggs.
They also encourage horse owners to vaccinate their animals against EEE.
