"The researchers trapped 100 wood mice in the fields around Nottingham and measured their loads of several different parasites, including various worms, mites, ticks, fleas and lice. As expected, immune cells from mice with roundworms produced less of an inflammatory chemical called TNF-alpha in response to germs than cells from uninfected mice. But surprisingly, says Bradley, mice with heavy louse infestations showed even stronger immune suppression, producing half as much TNF-alpha as uninfested mice. None of the other parasites, nor the animal's age, sex or general condition, was related to the production of the immune chemical [...] "The hygiene hypothesis was always associated just with worm infections, but this shows other kinds of parasites may have the same effect," Bradley says. That means ridding ourselves of lice, as well as worms and perhaps other parasites, might have caused the modern epidemic of immune hypersensitivity."
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