The Maricopa County Department of Public Health reported its first West Nile virus-related death on Monday.

The person who died related to West Nile was “an older adult” with “underlying” health conditions, according to a press release from Maricopa County Department of Public Health officials.

As of July 21, a total of 17 human cases of West Nile virus have been confirmed in Maricopa County in 2025. West Nile was first detected in Arizona in 2003, according to the ADHS website.

The disease is spread by mosquitos. Peak mosquito season is between May and October, the press release stated.

Symptoms include fever, headache, body aches, vomiting and diarrhea, according to the Maricopa County website.

“This tragic loss is a reminder that West Nile virus can be serious, especially for older adults and those with existing health conditions,” said Dr. Nick Staab, chief medical officer with Maricopa County Department of Health in a press release.

Summer months can see an uptick in mosquito activity as Valley monsoons bring higher humidity levels, rain and other conditions ideal for breeding, Stabb said.

“Monsoon season brings much-needed rain, but it also creates ideal conditions for mosquitoes to breed,” he said. “That’s why it’s so important for residents to stay vigilant—use insect repellent, drain standing water, and limit outdoor time during peak mosquito activity.”

So far, Phoenix has received 1.63 inches in 2025 as of July 21 at Sky Harbor International Airport, said Ryan Worley, meteorologist at the National Weather Service in Phoenix. This year’s rainfall is well below the normal of 3.44 inches of rain for this time of year, Worley said.

For information, visit https://www.maricopa.gov/5811/Fight-the-Bite.