Each type responds in different ways to foreign invaders. Rook believes this ratio depends on how many bacteria and viruses the immature immune system encounters. Remove bacteria and viruses from the environment, he says, and the immune system seems to make more allergy-inducing Th2 cells. In fact, lice seem to prefer clean hair. And overwashed skin can become dry and cracked, giving other pathogens a foothold.
Microbes are ubiquitous.
They're on our skin, in our bed linens, even in our bathtubs, notes Dr. Stanford Shulman, chief of infectious diseases at Children's Memorial Hospital in Chicago. E.W. Scripps Publications , All Rights Reserved. Site users are subject to our User Agreement . We also have a Privacy Policy .