The Fond du Lac County Public Health Officer says a recent potential exposure to measles in southwest Wisconsin should be warning for area residents to make sure they are immunized against the disease. The LaCrosse and Trempeleau county health departments were notified this week that an out of state visitor had measles. Fond du Lac County Public Health Officer Kim Mueller says its important that someone potentially exposed to measles and with symptoms stay isolated from others to keep from spreading it. “Extremely contagious,” Mueller told WFDL news. “If exposed to it, nine out of ten people who has no immunity will develop the disease.” Mueller says measles is a serious respiratory disease which can be prevented with a vaccine. Health officials say for every 1,000 children who get measles, one or two will die.