6-27-12 (Rochester, MN) -- Lots of Minnesota kids will be heading to large community swimming pools to cool off over the next few days. But a Mayo Clinic pediatric infectious disease specialist warns those pools contain germs that can linger. Dr. Thomas Boyce says it takes chlorine several days to kill a parasite called cryptospordium and during that time the germ can multiply and cause people to get sick if they swallow the water. Dr. Boyce also says people with diarrhea should stay out of the pool to avoid contaminating the water. He recommends showering before and after swimming in a community pool.