"When you first meet Moises VelasquezManoff the first thing you notice is his hair  or the lack of it. NPR  Hes completely bald. At age  I developed this condition called alopecia areata where I lost my hair says VelasquezManoff http a science writer in Berkeley Calif. It started in patches but eventually I lost it all. A few years ago VelasquezManoff was working on a book https about autoimmune diseases like allergies asthma Crohns disease and alopecia. He talked to many people who were using an unlikely tool to treat their problems parasitic worms that live in your gut  permanently. The worms were getting rave reviews. People were saying I had absolutely zero symptoms. And my disease went into remission VelasquezManoff says. So he started to wonder Could these worms cure his alopecia Maybe his hay fever too Courtesy of Moises VelasquezManoff  He went down to Mexico bought  hookworms and let the larvae infect him. Hookworm larvae are microscopic. But they have little spikes that puncture the skin and allow the larvae to burrow inside you. Then the critters head straight for a capillary. They basically ride your bloodstream back through your heart into your lungs where they hang out for a while VelasquezManoff says. Then the larvae crawl out of the lung through your stomach and into the small intestine  where they bite onto the intestinal wall and start sucking blood  a few drops a day. At that point the worms do something amazing They suppress the immune system says Png Loke http an immunologist at the New York University School of Medicine. Thats the really fascinating thing he says. You see the worms dont shut down the immune system completely  just enough so that the immune cells wont attack the worm. But this can help with something else. It can keep the immune system from getting out of control and attacking the body. If you think about it the worst thing that you want is an immune system thats out of control Loke says. Why Because thats when you get autoimmune problems. So the hypothesis is that intestinal worms could possibly reverse these problems by damping down the immune system. Article continues after this message from our sponsor The idea was so promising that back in  a pharmaceutical company decided to test it in clinical trials. Coronado Biosciences put together about six large studies httpsclinicaltrials.govctresultstermtrichurisSearchSearch. The first study to finish was a big one in Europe that looked to see if pig whipworms helped with Crohns disease. The bottom line The proportion of patients who improved with the worms was no different than the proportion of patients who were improved with placebo says Dr. Stephen Hanauer http at Northwestern University Feinberg School of Medicine who was involved with one trial. The whipworms were so ineffective at stopping Crohns disease that Coronado canceled its other trials. The companys stock plummeted. And eventually the company changed its name http and focus. Other trials with worms havent gone so well either says Hanauer. The controlled trials thus far in a variety of different diseases including childhood allergies and asthma have not been positive. Its unclear why the worms havent worked in these trials Loke says. It could be that the whipworm larvae werent prepared correctly. Or that the worms work for some people but not others. It may depend on a persons genes. Back in Berkeley VelasquezManoff thought he might one of the lucky ones. A little while after he took the hookworms his hay fever disappeared. Like just gone gone gone he says. And his hair Then I had like little bit of peach fuzzy hair growing here and there on my body VelasquezManoff says. But then the tide turned. Suddenly its like one day the whole thing reversed. His hay fever came back. The hair didnt grow anymore. And having worms in his body wasnt pleasant. At first he had diarrhea and cramps. That got better. But even months later he still felt kind of bad. I never got back to feeling completely normal for that year that the worms were inside VelasquezManoff says. He says the benefits of the worms definitely didnt outweigh the bad side effects. And he would never try treating his alopecia or hay fever with them again. The way I thought of it was would I give this to my kids And the answer is pretty easily and obviously Hell no VelasquezManoff says. I wouldnt want them to feel this way."