A Cumberland County resident has tested positive for West Nile virus.
The Maine CDC said the resident is in their 40s and has no history of recent travel, so they likely acquired the mosquito-borne virus in-state.
It's the first locally-acquired infection since 2020, health officials said.
Maine CDC Director Dr. Puthiery Va said mosquitoes are especially active this year.
"What I want folks to know is that the risk this season is higher than the risk last season," Va said.
Two other mosquito-borne diseases, Eastern Equine Encephalitis (EEE) and Jamestown Canyon Virus, have been detected in animals and mosquito pools in Maine.
Va said all three diseases start with symptoms such as fatigue, muscle aches and pain, similar to the flu and Covid.
"I want people to be aware that if you test negative for flu, or you test negative for Covid, it could be one of these arboviruses," Va said.
More serious and even fatal symptoms can develop, such as brain swelling and meningitis. The CDC said some may experience lifelong effects.
The agency said five counties are now at high risk for the viruses: Cumberland, Kennebec, Penobscot, Somerset, and Waldo. All other counties are at an elevated risk.
Health officials urge people to take steps to prevent mosquito bites, including wearing repellent, long sleeves and pants, and draining artificial water sources, where mosquitoes breed.
