Gut parasites linked to reduced asthma risk
04 January 2007

Gut parasites could hold the key to increasingly common conditions such as eczema, asthma and hay fever, according to new research supported by Asthma UK.

Gut parasites, such as hookworms, have evolved together with their human hosts for millions of years. Over time, these parasites have developed ways of surviving in the human gut by 'turning down' the immune response directed against them, prolonging their survival inside the host. This reduction in immune response may also reduce allergic tissue reactions that characterise asthma and other allergic conditions.

The study was led by Dr Carsten Flohr, a clinical scientist from The University of Nottingham and Dr Luc Nguyen Tuyen, from the Khanh Hoa Provincial Health Service in central Vietnam. It involved 1,600 children aged six to 18, in four neighbouring rural communities in Khanh Hoa province. Their lifestyles were studied, along with their sensitivity to common allergens and their level of infestation with hookworm and other parasites.

Those with the highest level of hookworm infestation were found to be least likely to have an allergic response to house-dust mites. These findings support the theory that infection of the gut with either hookworms or other parasites protects against allergy.

Dr Lyn Smurthwaite, Research Development Manager for Asthma UK said: ‘The “hygiene hypothesis” suggests that high rates of allergies and asthma in developed countries are a result of our immune systems becoming unbalanced due to improved sanitation and hygienic lifestyles that no longer expose us to the same array of bacteria, viruses or parasites. We look forward to future results in this area.’

In addition to a research grant from Asthma UK, the research was also supported by the Bastow Award from the Special Trustees for Nottingham University Hospitals and a Fellowship from University College, University of Oxford.