the world is just
too darn clean. So goes the “hygiene hypothesis,”
an attempt to explain why increasing numbers of people
suffer from allergies—sometimes life-threatening
ones—to peanuts and tree nuts.
Researchers led by pediatrics professor Dale Umetsu
decided to test the hygiene hypothesis by introducing
Listeria monocytogenes, a food-borne bacterium thought
to be responsible for fewer infections than it once
was, into the systems of allergic dogs. They created
vaccines by combining heat-killed Listeria with major
food allergens. Dogs allergic to peanuts went from tolerating
one peanut before vaccination, on average, to more than
37 afterward. Milk-allergic dogs exhibited a 100 percent
reduction in vomiting and a 60 percent reduction in
diarrhea.
This is the first time such a response has been shown
in an animal other than a
mouse. Dogs’ allergic symptoms are similar to
those seen in humans.
