Sunday, November 17, 2013
Will hookworms relieve my asthma?
Will hookworms relieve my asthma?
I recently heard that dust allergy woes could be helped by the noble but misunderstood hookworm. Apparently the parasite has been shown to calm the immune system when certain allergens make it overenthusiastic.
Long afflicted with severe asthma and allergies, Lawrence heard hookworms offered relief and promptly decided to get some, for which purpose he journeyed in 2006 to the tropical African country of Cameroon, where hookworm is endemic. Because (a) infected humans excrete worm eggs in their feces and (b) the resulting larvae typically burrow in through their host’s skin, Lawrence spent two weeks walking barefoot around village latrines and hoped for the best.
On returning to the U.S., Lawrence noticed no change till the spring day he rolled down his car window. Normally he would have been overwhelmed with allergy symptoms; instead, nothing. Petting a cat, previously perilous, likewise had no effect. Concluding he was cured, Lawrence decided he needed to bring the gift of hookworms to his fellow sufferers and began selling hookworm treatment kits online at four grand a pop, using worms he'd cultivated internally. (He says they're sanitized before they're shipped.) When the Food and Drug Administration went after him, Lawrence took it on the lam, although he can still be reached through his site. Meanwhile, he's gotten coverage from ABC News, Discover, Observer, and of course NPR.
In case you're tempted, I need to emphasize that Lawrence isn't a doctor and has no research to prove his worms work. However, and here we get back to David Pritchard, it's not out of the question that hookworms and their parasitic kin, collectively known as helminths, might offer some protection again asthma, allergies, inflammatory bowel disease, and other immune disorders. While working in the tropics in the 1980s, Pritchard observed that hookworm sufferers rarely had such problems. He became a believer in the hygiene hypothesis, which holds that we in the developed world receive much less exposure to infectious agents than our ancestors did, so our immune systems don't develop properly. As a result they overreact to harmless stimuli, giving rise among other things to what's been described as an asthma epidemic. Epidemiological studies purport to show that allergies and asthma are less prevalent in rural societies than in cities, that children with intestinal parasites have less severe allergic reactions, and so on. Pritchard became particularly interested in hookworms and at one point deliberately infected himself with them.
All very interesting, if a bit gross, but two points need to be made. First, no one has demonstrated that filling somebody with worms is going to cure his asthma or anything else. Although helminths and the hygiene hypothesis have been debated for decades, clinical research has barely begun. I could find only a few studies, each involving a few dozen participants. In one, porcine whipworms supposedly relieved ulcerative colitis; in another, hookworms failed to significantly improve asthma compared to a placebo. Second, even if worms conferred some clinical benefits, they're still, let's face it, worms — ones that can cause anemia, stunted development, and sometimes death, making this a suboptimal therapeutic method.
That’s not to say using one affliction to cure or prevent another is inherently nuts, just that there may be an intervening step or two before we arrive at a practical technique. Consider the famous example of Edward Jenner, who infected people with cowpox to prevent smallpox. What’s little remembered now is that cowpox vaccination replaced variolation, in which people were purposely inoculated with smallpox scabs in hopes they'd get a mild form of the disease to prevent a later fatal case. The technique worked — 98 percent of those variolated became immune. The drawback was that one to two percent died.
Why doctors are treating allergies with parasitic worms
Researchers found that Papau villagers with more fertile parasites had lower levels of allergy-related antibodies in their blood, suggesting the hookworms had found a way to nerf their hosts' immune responses. Since allergic response is tied to the body's immune system, it stood to reason that the absence of autoimmune disorders like asthma and hay fever could be attributed to the hookworms; the parasite's survival response was actually benefitting its host, in one of the most roundabout ways imaginable.
"The allergic response evolved to help expel parasites, and we think the worms have found a way of switching off the immune system in order to survive," hypothesizes Pritchard in an interview with the New York Times. "That's why infected people have fewer allergic symptoms."
And Pritchard's hypothesis has been holding water, both in his own experiments as well as others. Symptoms from autoimmune disorders ranging from asthma to Crohn's disease have been shown to be noticeably reduced in study volunteers administered "safe doses" of hookworm therapy. Clinical trials that use hookworms to treat Multiple Sclerosis are slated to begin later this year.
"The challenge for those of us using necessarily lower levels of worm infection in humans is to mimic the positive effects seen in animal models using alternative and inherently safe strategies," writes Pritchard in a recent perspective on the potential benefits of hookworm infection, "such as boosting with low-level ‘trickle infection', as is likely to occur in the tropics [where hookworm infection is especially common]."
"This will be an interesting immunological journey, and early indications suggest that therapeutic dosing regimes can be developed."
(I know it does sound like obama witch doctor medicine but it seems to be a possible therapy
for people in the future if they can find out how to control the hook worm shutdown of the immune system. Its better than nothing, like obamacare.) Story Reports