If you had a germ detector in your home, where would it lead you? Straight to your baby's nursery or Junior's playroom. Since this is where your kid spends a good chunk of time, you need to zero in on these nasty germs—E. coli, rotavirus, cold, and flu -- before they make him sick. Charles Gerba, Ph.D. (aka “Dr. Germ”), professor of microbiology at the University of Arizona, Tucson, identifies the hot spots and how to treat them.