This week, a sample of the mosquito population in Larimer County in Northern Colorado tested positive for West Nile virus. County health officials say this marks the beginning of heightened risk for residents, as warmer weather and rain lead to more mosquito activity.

About 1 in 5 people infected may develop flu-like symptoms, including fever, headaches, body aches, fatigue, vomiting, diarrhea, and rash. About 1 in 150 people who are infected develop more severe illness, which includes symptoms of high fever, headache, tremors, muscle weakness, vision loss and paralysis. 

When Lisa Montez visited Fort Collins in the summer of 2022, she never imagined a mosquito bite would turn her life upside down. What started as mild fatigue turned into a months-long ordeal that left her unable to drive, plagued by chronic fatigue, and permanently impacted by the bite.

"The next day, I woke up and was very, very tired. But I figured, because I was traveling and we were with family, that it was just a normal vacation tied," Montez said. She returned home to Washington.

Within days, Montez broke out in a full-body rash. Doctors initially suspected something minor - maybe an ear infection or just a viral bug. But despite multiple visits to urgent care and emergency rooms, her condition worsened with no clear answers.

It took two months and a battery of tests before doctors finally diagnosed her with West Nile virus.

Montez, a healthy woman in her 30s, ended up with a rare neuroinvasive form of the illness.

"My husband was doing everything on his own. I couldn't do laundry, I couldn't cook, I couldn't clean. A lot of times I was just in bed because I was so dizzy or I was so tired," she explained.

She wasn't able to drive a car for about a year. Her family returned to Colorado to get support from family and treatment at UCHealth. Montez was in vestibular rehab for 11 months and in occupational therapy for eight months.

"I think that had we not come back, I wouldn't be where I am, and I wouldn't have progressed as far as I have through this with the support that I had. So I'm very grateful for UCHealth and for all of the time that they invested," she said.

People ages 55 and older are at higher risk of serious symptoms if they get West Nile virus. People with health conditions such as cancer, diabetes, and hypertension, and who have had organ transplants or are taking medications that suppress the immune system, are also at risk. 

There are no vaccines to prevent West Nile virus. Dr. Bob Belknap, Director of the Public Health Institute at Denver Health, says if people have it, it's supportive care.

"If someone is feeling sick, and if they have any concern at all, we recommend that they seek medical care. Do not hesitate. People usually know if something is mild and it's manageable, something they can treat with over-the-counter medications," he said. "If it's at all concerning, or if it's getting worse despite those treatments, then definitely people should seek care."

The Health Department urges all residents to adopt effective protective measures as part of their summer routine:

• Regularly use an EPA-registered insect repellent.
• Wear loose-fitting long-sleeved shirts and pants for long walks, gardening, and other times outside.
• Avoid outdoor activities during peak biting times around dawn and dusk.

Montez says the experience completely reshaped how she approaches outdoor activities.

She hopes her experience reminds others not to brush off those bites.

"I have nerve damage in my body. My left side was impacted more than the rest of my body, so I have weakness in the left side of my body. I actually have a little bit of drooping in this side of the face," she said. "I'm better today, but I will have lifelong effects from this."