Pets do an awful lot for kids: they teach them about
unconditional love, responsibility, death and, of course, pooper
scoopers. But does a dog or cat also keep a child from
developing allergies? Despite decades of research, the short
answer is still a frustrating "maybe." The idea that pets might
provide an immune benefit stems from a controversial theory born
in 1989 called the hygiene hypothesis. It postulates that the
sharp rise in allergic diseases this century can be explained,
at least in part, by our higher cleanliness standards.
Microorganisms like bacteria and parasites are thought to
"prime" our immune systems to fight the important
fights—dangerous infections—while smartly ignoring the frivolous
ones. Allergies, then, occur because naive immune systems
unnecessarily attack harmless environmental triggers, such as
pet dander. Today, most researchers believe that only certain
microorganisms, such as parasitic worms and lactobacilli, play a
role in prepping the immune system. The question is whether p