The Ross County Health District (RCHD) reported the case on Wednesday, urging residents to take precautions to prevent further infections. Symptoms of severe cases may include fever, headache, nausea, vomiting, and, in rare instances, neurological complications such as encephalitis. “La Crosse virus is spread to humans by the bite of an infected mosquito,” Kelley said. To combat mosquito breeding, RCHD is hosting its annual tire drive on Saturday, October 11, at the Ross County Fairgrounds. Background on La Crosse VirusLa Crosse virus is a mosquito-borne illness first identified in La Crosse, Wisconsin, in the 1960s.