GRAYSON COUNTY, Texas (KTEN) — The Grayson County Health Department set out nine mosquito traps around the county last week.

One sample from a trap on Elm Street in Whitesboro tested positive for West Nile virus. Mosquitoes can transmit the sometimes-fatal illness to humans.

Health department director Amanda Ortez said Whitesboro city officials have been notified.

"It's up to individuals as well to take that proactive stance and try to make sure they mitigate the risk," she said. "Just watch the dress, the drainage, and the dusk 'til dawn... especially for these types of mosquitoes that carry the West Nile virus."

This is the first positive sample identified this year in Grayson County.

The Centers for Disease Control says most West Nile patients do not feel sick; about 1 in 5 develop a fever and other symptoms.

About 1 in 150 who are infected can suffer a serious, sometimes fatal, illness.