Westchester County confirmed its first human West Nile virus case of 2026 on Tuesday, Sept. 1, weeks after infected mosquitoes were trapped in Rye.

The county health department identified the case in a Yonkers resident who had recently traveled outside the county.

Health department staff are investigating whether the exposure occurred during that travel or closer to home.

The case follows a summer of escalating detections in Rye. On Aug. 6, the county reported that the season's first West Nile-positive mosquitoes were found in the city. Those were the first positives out of 61 batches collected from 30 traps countywide.

West Nile virus most often causes mild or moderate flu-like symptoms, including fever, headache, body aches and joint pain.

The illness can be more serious for people 65 and older and those with underlying medical conditions, according to the health department.

Westchester County Health Commissioner Dr. Sherlita Amler urged residents to take action. She said the first confirmed case should prompt residents to check their own yards.

"To avoid breeding mosquitos in your own yard, remove all standing water around your home after it rains, and use repellents when you spend time outdoors, especially from dusk to dawn, when mosquitoes are most active," Amler said in the county's Sept. 1 announcement.

The health department advises residents to check flowerpot drip trays, kiddie pools, play equipment and other items that collect water. Birdbath water should be changed at least twice a week. Storm drains and gutters should be kept clear.

When outdoors, the county recommends wearing long pants, long-sleeved shirts and socks, and using insect repellents with up to 30 percent DEET.

Residents who spot large areas of standing water on public property can report them to the County Health Department at (914) 813-5000.