Lesser of Two Evils?

Some days I spend a fair amount of time reading news without coming across anything that stimulates a post. Today was like that until a few minutes ago, when my wife pointed out this story, via InstaPundit:

As blossoming spring trees spew pollen, many allergy sufferers would be grateful for a more effective way to alleviate their itchy misery. How about swallowing a batch of pig whipworm eggs, or deliberately infecting oneself with the fecal-dwelling hookworm? Yucky as these options sound, mounting evidence in both humans and animals suggests that infection with these parasitic worms seems to protect against a number of inflammatory diseases, including asthma and allergy, multiple sclerosis, Crohn’s disease, and type 1 diabetes.

As an allergy sufferer, I’ve always wondered why, throughout history when pretty much everyone lived in close contact with horses, cows, hay, etc., many of them weren’t disabled by allergies. Likewise, why do diseases like multiple sclerosis seem to be growing more widespread? Maybe the demise of parasitic worms is the explanation, or part of it.

A number of epidemiological studies have shown that people infected with parasitic worms suffer less from allergies and other immune diseases, and research in animal models designed to mimic these diseases supports these findings. The rise in allergies and other ailments in rich countries over the last few decades has been matched by a decrease in parasitic worm infection, among other factors.

The mechanism whereby parasitic worms protect against auto-immune reactions isn’t clear, but it seems plausible that an ability to inhibit immune response could help a parasite to survive in the body:

Because parasitic worms coevolved with us for the vast majority of human history (even mummies have them), they likely evolved ways to turn down the immune system just enough to permit their survival without severely harming their hosts. “I think the consensus, if there is one, is that chronic worm infections induce an immunoregulatory response in the body,” says Mitre. “Exactly how that immunoregulatory milieu is set up remains unknown.”

Who knows? Maybe worms will join maggots on medicine’s low-tech frontier.


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