Almost 75 percent of swine flu cases in Wisconsin involve patients under 19
Almost three of every four swine flu cases in Wisconsin involve patients under 19, and officials are not sure why.
Marathon County Health Officer Julie Williams Van Disk tells the Associated Press there's no indication that today's virus is any stronger than the 1970s version.
And she says experts are investigating whether those who had swine flu three decades ago have some type of protection that a child doesn't have today.
Wisconsin has about 3,500 confirmed and probable cases of the H1N1 virus, and four people in the state have died from it, two children and two adults.
Nationally, there are more than 21,000 confirmed swine flu cases and at least 87 deaths as of earlier this month.