A study conducted in Vietnam has added further weight to the view that parasitic gut worms, such as hookworm, may be able to help researchers develop new therapies for the prevention and treatment of asthma and allergies.
Dr Carsten Flohr (The University of Nottingham) and Dr Luc Nguyen Tuyen (Khanh Hoa Provincial Health Service, Vietnam) collaborated on this study, which is the largest double-blind placebo controlled clinical trial to date looking at the potential links between hookworm and other gut worm infections and allergic conditions such as asthma and eczema.
This research does not suggest that we all run out and find some gut parasites to infect us -- instead, it points out that in certain populations where poor hygiene practices allow the citizenry to catch these parasites, the amount of allergies and asthma is much lower than in more "developed" nations. In countries such as Vietnam, scientists find that as these hygienic practices improve, the incidence of allergies and asthma goes up. Experts believe that over millions of years of co-evolution worms have found methods to dampen down host immune responses to prolong their own survival inside humans. This relationship seems to have become so intertwined that without gut worms or other parasites, our immune system can become unbalanced, which in turn could contribute to the development of asthma and other allergies.
Dr Flohr’s study was conducted in a rural area of central Vietnam where two out of three children have hookworm and other gut parasite infections and where allergies are extremely rare. More than 1,500 schoolchildren aged 6-17 took part.
The team investigated whether repeated tablet treatments to clear the body of gut worms made it more likely for children to develop allergic conditions. The treated children were found to have a significantly increased risk of a positive allergy skin test to house-dust mites and cockroach. This suggests that gut worms have the potential to tone down human immune responses, and as a result further research is now needed to identify precisely how gut parasite infection can prevent allergic sensitization.
Dr Carsten Flohr of The University of Nottingham adds: “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.”
We may someday soon discover something about the way that hookworms adapt our immune system which will allow us to develop a therapy to mimic that action, saving countless millions from the agony of allergies and asthma.