Rock County Public Health is reporting its first human case of West Nile virus for the year.
Health officials warn that while infections peak late in the summer, risk remains active until temperatures drop below 28 degrees for four consecutive hours to create a hard frost.
Most people infected show no symptoms or experience only mild fever and fatigue, though severe neurological complications can occur in rare cases.
Neighboring Dane and Sauk counties have also confirmed human infections this season, prompting regional guidance on insect repellent and protective clothing.
