So why have our immune systems suddenly gone haywire? One theory notes that we (mostly) eradicated hookworms by the 1980s in the United States. And tapeworms. All the classic parasites are mostly kaput. Without those actual threats, our immune system downshifts to tackle the biggest possible threat on the horizon. Which, these days, might be cashew butter or Camembert.
“It’s looking for stuff to do and it’s staying busy,” Warren said. “But it’s busy doing stupid stuff like reacting to walnuts and birch pollen.”The Washington Post