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.
