While this scenario might appear to be win-lose, with humans the clear losers, research now suggests that may not be the whole story. In their drive to make humans hospitable hosts, parasites have developed the ability to suppress inflammation aimed against them. And this, it turns out, isn’t necessarily a bad thing.
“They have evolutionarily adapted to this long-standing interaction with their hosts — that’s us — and developed strategies to help the host dampen its immune response,” says Helmut Haas, an immunologist at the Research Center Borstel in Germany.
These strategies are not subtle. But humans have survived the effects and even adapted well to them: A toned-down immunity is, perhaps, the norm. A sober immune system might still defend against enemies while not overreacting to everyday substances in the environment, or otherwise going awry. Suddenly those prehistoric times don’t sound so bad — no Crohn’s disease, no multiple sclerosis, no asthma. Good old Stone Age.
In a stroke of medical inspiration as bold as it is counterintuitive, scientists are now testing this theory by treating patients with live microscopic eggs or larvae of parasitic worms designed to quell these very afflictions. Several clinical research trials are under way and more are planned. Whether promising early results will lead to treatments for these known or suspected autoimmune conditions — and extend to allergy, type 1 diabetes, psoriasis and other cases of immune revolt — remains to be seen.
Perhaps we are too “clean” for our own good.