By looking at the exposure to the parasitic roundworm Ascaris lumbricoides/suum in Nothern Europe (Norway, Denmark and Estonia), the study finds that younger men exposed to Ascaris had a striking reduction in lung function and nearly five times higher odds of having asthma compared to the non-exposed. These effects were independent of smoking and other exposures such as house dust mites.

The paper «Ascaris exposure associated with lung function, asthma and DNA-methylation in Northern-Europe» was just published in The Journal of Allergy and Clinical Immunology.

The study is a collaboration between the University of Bergen, Tartu University Hospital Lung Clinic, University of Aarhus, the University of Birmingham and the University of Cape Town.

Differences in gender

A curious finding in the study was that among women, lung function was not significantly lower in the Ascaris seropositive. In fact, the seropositive appeared to have even less asthma than the rest. This is the first research of its kind to show substantial gender differences in terms of helminth (parasitic worms) exposures and subsequent outcomes in humans.

The researchers also found that Ascaris infection in Europe might be an overlooked risk factor for asthma and respiratory health.

May result in lung damage

It has previously been assumed that infections of roundworms have not been of significance in Europe, but the new findings indicate that exposure could potentially be a lot more common than assumed. For persons affected, this may result in serious lung damage with the risk of having a long-term impairment of lung function

Parasitic worm-infections are normally considered to be a problem only in low and middle-income countries. These findings present them as being of much greater importance in Europe.

This is also the first study to report a connection between reduced lung function and Ascaris exposure, according to the researchers.