Cleanliness is Next to Godliness

A funny thing happened on the way to a cleaner, brighter future...

Here'a an article in the NY Times by Moises Velasquez-Manoff that points out that humans were built to be all that clean:

At the time, Weinstock, then at the University of Iowa, was editing a book on parasitic worms. These worms, or helminths, have a paradoxical effect on the host. Rather than induce inflammation, which is the body’s typical response to invasion, the intruders calm the host immune system. They force a peace, scientists think, to avoid eviction and keep the host — their home and food source — as healthy as possible. As Weinstock considered the I.B.D. puzzle, he wondered if immune manipulation by worms could incidentally protect against other diseases.

Comparison of the prevalence of I.B.D. and surveys of worm-infestation rates revealed a telling pattern. About 10 years after improved hygiene and deworming efforts reduced worms in a given population, I.B.D. rates jumped. Weinstock had his hypothesis: after a long coevolution, the human immune system came to depend on the worms for proper functioning. When cleaner conditions and new medicines evicted the worms from our bodies, the immune system went out of kilter. “Hygiene has made our lives better,” says Weinstock, now at Tufts University. “But in the process of eliminating exposure to the 10 or 20 things that can make us sick, we’re also eliminating exposure to things that make us well.”

At the time of Weinstock’s initial musings, epidemiologists had already dubbed this notion “the hygiene hypothesis”: as improved hygiene reduced exposure to certain infectious agents, the immune system began malfunctioning. By the late 20th century, autoimmune disorders, characterized by the body’s defenses attacking some aspect of the self, had increased markedly, and allergic diseases, defined by an overblown immune response to nonthreatening substances, afflicted almost half the people in the developed world.

If eliminating worms led to an increase in disease, could re-introducing worms actually treat these diseases? In mice, the answer was yes. Worms were used to “inoculate” against mouse asthma, Type 1 diabetes, multiple sclerosis and I.B.D. But how to re-worm humans? We got rid of them for a reason. Too many worms can lead to anemia or obstructed bowels. The wrong kind can cause considerable suffering, even death.

Go read the article to find out how this scientific sleuthing ended!