There are 18,000 reported cases of Shigellosis every year in the United States. What makes the cases at Willow Elementary School different is that the illness is normally seen in much younger kids, kids that are not fully toilet-trained yet.
The bacteria, shigella, can be spread from contaminated stool that gets on food or other objects and then are put in someone's mouth. The best way to prevent this is good hygiene and hand-washing.
Dr. Scott Rosenfeld of Ingham Regional Medical Center says the bacteria can be everywhere and, "It probably just somehow got into food or water at the school."
He says symptoms of the illness usually present one to two days after exposure, but they can be seen up to week after coming in contact with the bacteria.
The bacteria can also stay in stool for more than two weeks, making someone infected contagious for that time as well.