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Parasitic roundworm can lead to more cases of asthma in young men.

Young men exposed to parasitic roundworm may be at increased risk of developing asthma and serious lung damage, a new study reveals.

Exposure to ‘Ascaris lumbricoides’ in Europe appears much higher than previously assumed, with young men exposed to the worms showing significant reduction in lung function and asthma nearly five times more often, as compared to those not exposed.

Researchers studied 671 adults from Norway, Estonia and Denmark – discovering reduced lung capacity among men, independent of smoking and other factors such as exposure to house dust mites.

They found no connection to reduced lung function in women and symptoms of asthma were also significantly fewer among women exposed to the parasite than in men.

Researchers at the Universities of Birmingham, Bergen, and Cape Town led an international team which today published its findings in Journal of Allergy and Clinical Immunology. The scientists noted that the outcomes were unexpected as it had been assumed that roundworm infections are not of medical significance in Europe.

Lead author Dr. William Horsnell, from the University of Birmingham, commented: “Parasitic worm infections are typically thought to only be a problem in Low- and Middle-income Countries, but they may potentially be much more important in Europe – they could be an overlooked risk factor for asthma and poor respiratory health.

“Exposure is possibly much more common than expected and may result in serious lung damage that could lead to long-term breathing problems – particularly for young men who are exposed to Ascaris.”

Ascaris lumbricoides infection affects at least 800 million people world-wide, but infection caused by the parasitic roundworm was assumed to be rare in developed countries and not cause major medical issues.

The study, first-authored by Dr. Nils Oskar Jõgi, is believed to be the first to address lung function and roundworm infection in adults in Europe, as well as the first to show substantial gender differences in exposures and subsequent outcomes in humans.

“The effects were surprisingly large, with much lower lung function and much higher asthma related to Ascaris – in men only. Parasitic worms are clearly an underappreciated cause of infection and respiratory problems in Europe, and may have implications for patients suffering from additional lung infections and diseases,” added Dr. Jõgi.

“Such infections warrant the development of new diagnostical awareness. We hope this discovery will boost efforts to understand how parasitic worm infection influences the development of serious respiratory conditions in both developed and developing countries.”

  • For more information, please contact Tony Moran, International Communications Manager, University of Birmingham on +44 (0)782 783 2312. For out-of-hours enquiries, please call +44 (0) 7789 921 165.
  • The University of Birmingham is ranked amongst the world’s top 100 institutions. Its work brings people from across the world to Birmingham, including researchers, teachers and more than 6,500 international students from over 150 countries.
  • ‘Ascaris exposure associated with lung function, asthma and DNA-methylation in Northern-Europe’ - Nils Oskar Jõgi MD, William Horsnell PhD, Cecilie Svanes MD; PhD, Randi Bertelsen PhD is published by J Allergy Clin Immunol.
  •  Participating institutions were: University of Bergen, Norway; University of Birmingham, UK; University of Cape Town, South Africa; Aarhus University, Denmark; Tartu University Hospital Lung Clinic, Estonia; University of Southampton, UK.