The study, headed up by Dr. Carsten Flohr of the University of Nottingham and Dr. Luc Nguyen Tuyen of the Khanh Hoa Provincial Health Service, is the largest double-blind placebo controlled clinical trial testing the links between gut worm infections and allergic conditions.
A little background on this unusual and somewhat distasteful theory: Experts believe that over millions of years of co-evolution, worms have found ways to suppress the immune responses of their hosts (including humans) in order to prolong their own survival. Resultingly, our immune systems have become so used to this relationship that without gut worms, our immune responses can become unbalanced. With improvements in hygiene, parasitic worms have been nearly eradicated in humans living in developed countries. Some think that that unbalanced immune systems could account for the development of asthma and allergies.
The researchers conducted their study in rural central Vietnam, where two out of three children suffer from hookworm and other gut parasite infections – and where allergies are also extremely rare. The team looked at whether treatments to clear the body of the parasites made it more likely for the children to develop allergic conditions.
The results? The treated children did not demonstrate an increased risk of asthma or eczema, but did exhibit a significantly increased risk of having a positive skin allergy test to dust mites and cockroach allergen.
While the findings suggest that gut worms do have the potential to tone down human immune responses, further research is necessary to determine exactly how gut worm infection prevents allergic reactions. As Dr. Flohr puts it, ‘The next step is to understand exactly how and when gut parasites program the human immune system in a way that protects against allergic sensitization, and for such studies, follow-up from birth will be essential.’
Note: It's important to remember that gut parasites can cause severe disease and are a major cause of iron deficiency in developing countries.