There was an article a couple of weeks ago in The New York Times about a study that uses hookworms as a treatment for allergies, such as hayfever. The general idea is that people with hookworms have T-cells that produce less of the chemicals associated with inflammatory response.
While carrying out field work in Papua New Guinea in the late 1980s, he noticed that Papuans infected with the Necator americanus hookworm, a parasite that lives in the human gut, did not suffer much from an assortment of autoimmune-related illnesses, including hay fever and asthma. Over the years, Pritchard has developed a theory to explain the phenomenon.
"The allergic response evolved to help expel parasites, and we think the worms have found a way of switching off the immune system in order to survive," he said. "That's why infected people have fewer allergic symptoms."
via www.nytimes.com
A hookworm - yecch:
The downside? According to the CDC, hookworm can lead to serious complications in pregnant women, children, and malnourished persons. This is not a course of action for allergy sufferers who could be so compromised - or for those those of us who are just plain grossed out by the whole concept.... Still there is a following for this remedy - just try googling "helminthic therapy".
And, since we're on the subject of parasitic worms here, success is being met to eradicate Guinea worm disease. As recently as the late 80s, there were more than 20 million persons infected by it. If you think hookworms are disgusting, this is from the Carter Center:
Guinea worm disease is contracted when a person drinks stagnant water that is contaminated with microscopic water fleas carrying infective larvae. Inside a person's body, the larvae grow for a year, becoming thin thread-like worms, up to 3-feet-long. These worms create agonizingly painful blisters in the skin, through which they slowly exit the body. People with emerging worms must not bathe or step in sources of drinking water, because a worm will release hundreds of thousands of eggs, or larvae, into the water. Water fleas then eat the larvae, and people who drink unfiltered water from the pond become infected -- continuing the life cycle of the parasite.
A guinea worm - higher degree of yecch:
Today, only a few thousand cases remain, mostly in Sudan. You can read about the stunning success of the eradication efforts (largely due to The Carter Center) in this post, Eradicating the Guinea Worm, at PRI's The World.