For many visitors to the Minnesota State Fair, wandering through the animal barns, listening to the indignant squeals of jostling pigs or watching a 1,500 pound cow unfurl its long tongue to snag an out-of-reach kernel of grain, is one of the fair’s great pleasures.

But even though the animals are bathed and brushed to perfection, they can carry germs that can make people sick.

The risk was made apparent earlier this month, when an E-coli outbreak that sickened 13 people was traced to a traveling petting zoo that appeared at several Minnesota county fairs and festivals. Seven people were hospitalized and two patients developed serious kidney complications.