Moises Valasquez-Manoff believes our immune systems are bored, and they're taking it out on us.
Modern hygiene has wiped out most of the parasites, bugs, and other microbes that afflicted our forbears and kept their immune systems busy. The result, the theory goes, is allergies and autoimmune diseases — rheumatoid arthritis, Crohn's disease, psoriasis, and asthma — in which the immune system treats the body's own tissues as the enemy.
Valasquez-Manoff himself suffers from two autoimmune disorders: asthma and alopecia areata, in which the immune system attacks the hair follicles. He has been completely hairless since adolescence. His asthma has lessened since childhood, when it landed him in the emergency room several times a year, but he still uses an emergency inhaler several times a day. Like many modern kids, he also grew up with food allergies.
As a science writer, Velasquez-Manoff wondered why doctors could not tell him why he was sick. But he wondered even more why these disorders, rare just two generations ago, are so common today.
"I just wanted an explanation. No one could give me an explanation," he says.
He thought he had a clue in the fact that this "epidemic," as some public health professionals call it, was occurring in the wealthy parts of the world, and not in the places where people still live in close contact with mud, animals, and parasites.
So two years ago, Velasquez-Manoff traveled to a clinic in Tijuana, Mexico, to receive hookworm therapy. A fluid containing hookworm larvae was squeezed onto a bandage, which was taped to his arm.
"You feel this itch," he remembers. "It is actually a very famous itch… It is the microscopic larvae burrowing through your skin," he explains.
The hookworm larvae travel through the bloodstream to the lungs, where they mature. From the lungs they crawl up the windpipe, over the epiglottis (perhaps while you're sleeping), and down the esophagus to the gut, where they reproduce, passing new larvae out through your feces to infect other people. (The American South, Valasquez-Manoff says, eradicated hookworm in the 1950s with a campaign to build privies.)
How did he feel after being infected with hookworms? "I had a pretty strong immune response. I had epigastric pain, aching…and lethargy. It wasn't terrible, but it definitely didn't feel good," he says.
It also didn't cure his asthma or grow back his hair, though he says he did have "peach fuzz growing here and there" for a while. And it gave Velasquez-Manoff a good "hook" for a book, his first, titled An Epidemic of Absence: Destroying the Bugs in Our Bodies Can Be Dangerous to Our Health.
After the Hookworm Infestation
Valasquez-Manoff took de-worming drugs to wipe out the infestation. He doesn't recommend hookworm treatment for anyone else and says he wouldn't do it again himself. But he also doesn't believe his case disproves the theory that our inactive immune systems are behind the explosion of autoimmune disorders.
"The hypothesis is really that if you grow up with parasites you won’t develop these diseases over the course of your life. But it’s a different idea than already developing the disease and treating them with parasites," he says. "If we evolve with these things always present, tweaking our immune response, we would never have the opportunity to make the mistakes that lead to autoimmune diseases or allergic responses. I think that still holds true."
"Let’s say that my asthma went into remission and my hair grew back," he adds. "That wouldn’t prove the theory either... because that’s not how science works. It’s just an anecdote."
And his book includes another anecdote in which hookworm therapy appears to have worked: a man who found relief from a severe case of psoriasis.
Velasquez-Manoff is not recommending an end to modern hygiene, but thinks this new understanding of how human beings and parasites interact may lead researchers to new kinds of therapies, perhaps even "domesticated parasites."
"We have lost contact with certain microbes and parasites that have been with us since time immemorial," he says. "Our immune system expects them to be there. When they go missing, our immune system begins making mistakes."
Last Updated: 2/1/2013