This is gross
My friend Jon sent me this link to the (perhaps a tall and certainly incredibly gross) tale of a man who cured his serious adult-onset asthma by contracting Hookworm in Cameroon. He did this mainly by walking barefoot through public latreens.
His theory goes that in the western world asthma and other auto-immune system diseases (such as Crohn's -- thus my interest in this article) are becoming increasingly prevelant because we are increasingly avoiding the dirty world. Our immune systems, built up over tens of thousands of years to deal with the worst nature can throw at us, are now bored and so take to picking on healthy tissue rather than just going on vacation.
Hookworms, in order to avoid being destroyed by the body, produce a compound that suppresses the immune system's response (by sending it a free all-expense paid ticket to the destination of its choice, perhaps?). And lo, the symptoms of the auto-immune disease go away... Hookworm's die off and do not breed in the body so the benefits of this treatment are dependent on a continuing vector for hookworm infection.
While I salute this man's gung-ho attitude, and I appreciate the desperation that led him to this course of action, I must say that I most certainly do not want this hookworm treatment. It's really just gross.
There's a couple articles on the BBC: here's a pretty old one, and here's one that's even older. (The BBC sure loves it's close-up pictures of hookworm.) And here's a pretty recent reference in The Observer. Note how none of these articles understands (or even discusses) the mechanism hookworm uses to suppress the immune system. As they say in Legend of Zelda, It's a mystery to everyone.