The Parasite Underground (NYT)

http://www.nytimes.com/2016/06/19/magazine/the-parasite-underground.html

"In the early 2000s, some multiple-sclerosis patients at a neurology clinic in Buenos Aires began showing up with parasite infections. Aware of the potential for parasites to help inflammatory disease, the presiding neurologists proposed an experiment: Don't treat the parasites, and see what happens. Twelve patients agreed, and for nearly five years the doctors monitored them. Disease progression, as measured by brain scans, slowed significantly. Blood work showed an elevation of "suppressor" cells that prevent autoimmune diseases. And when, more than five years later, the doctors dewormed four patients who complained of malaise, those suppressor cells disappeared, and the disease started up again."