Well, I bet that's how the wizards who run the camps kept from getting sick. I mean, I bet they don't ever really get very close to the muggles. Even before anybody was really sick, they all talk about them like they're contagious. They talk about the muggles that way, I mean. Look how people treat Hermione and Dennis. Even Malfoy, and Dennis serves him food and stuff, but he still acts like Dennis smells bad. Harry's not really like that about Hermione, exactly. But loads of other people are.

Anywiz, I bet the camp bosses just stay in their offices all the time and hardly ever get close to any but a few of the muggles.