Health officials say an initial test from the state hygiene lab is positive for a Fond du Lac County man. The test sample is being forward to the U.S. Centers for Disease Control and Prevention for confirmation.
Because the man traveled outside Wisconsin during the time in which he could have been infected, health officials can't determine where he was exposed to the virus.
West Nile has been found in birds and horses in 13 counties so far this year.
Last year 52 Wisconsin residents got sick with West Nile virus and three people died. West Nile is transmitted to humans through the bite of an infected mosquito.