As a first-grade teacher, Julie Miller is exposed to a horrifying number of germs on a daily basis.
"I've been thrown up on; they sneeze and cough on me. And lost teeth are a real big thing for first-graders," said Miller, who teaches at Spring Hills Elementary in the suburbs of Chicago.
"They're so cute and unaware, though. They'll have boogers hanging out of their nose and will be talking to you and not think anything of it. Some teachers flip out, but I tell my students, 'Go get a Kleenex and wash your hands.' When they sneeze, I teach them to do it into their elbows. They learn eventually."
On average, elementary school children get eight to 12 colds or cases of the flu each school year, according to the CDC. For the older kids, it is about half that. Teachers and parents commonly refer to it as the Back-to-School Plague.
But there are simple ways to keep your kids healthy.
Miller, who is getting her son Justin ready to go to kindergarten, isn't worried.
"I've taught my kids healthy habits; I'm sure they'll be fine," Miller said. She makes sure they get plenty of sleep, exercise regularly and eat healthy food. She's taught her children to wash their hands often, and she's hooked antibacterial gels on their backpacks for when they can't.
"I'm not a germaphobe like some of my colleagues who have put antibacterial lotion all over the place: their cars, their classrooms," Miller said. "I do feel like some germs are OK."
Germ candy stores: that's what Dr. Harley Rotbart, a professor of pediatrics at the University of Colorado and author of the book "Germ Proof Your Kids," calls schools.
"It is stunning how many times kids touch their faces and then touch other kids," Rotbart said. "This is a very touchy-feely demographic, and that's how we share germs. ... And the little ones don't have the same exposure to germs that we do, so until their immune systems get built up, they get sick."
Schools are full of "hot zones" for germs, Rotbart says. "Most people think that's the bathroom, but it really isn't. Those get regularly cleaned."
If he had to rank the germiest places in school, No. 1 would be the drinking fountain. It's germier than the toilet seat, he says, but "doesn't get disinfected as much." Plus, it's the perfect spot for kids to ingest these microorganisms as they put their mouths on the stream of water -- or right on the fountain itself.
Rotbart suggests teaching students to run the water a little first and then drink. Or better yet, children should bring their own water bottles to school and not share them with anyone.
Cafeteria trays are another germ hot zone. "Those don't get wiped down nearly as well," he said, recommending that kids bring the tray to their table and then use hand sanitizer before they pick up their food.
"There is a real delicate balance though; we don't want to make kids paranoid," Rotbart said. "We need to be prudent. Germs for people who are healthy really aren't a big deal."
Rotbart tells parents to make sure their children get enough rest. School-age children should get get 10 to 11 hours of sleep every night, according to the CDC. Sleep deprivation lowers the immune system's ability to fight off infection.
Exercise, Rotbart says, is another effective way to keep kids healthy. He suggests a daily dose of 40 minutes of running-around time, even in the winter. If it's cold, children need to keep their jackets zipped and hats on their heads.
"Your mother was right: Studies have shown that people who do bundle up against the cold are less likely to catch colds later on in the year," Rotbart said.