Parasitic roundworm increases asthma and lung damage rates in young men – study

Parasitic roundworm may increase the chances of young men developing asthma and serious lung damage, a new study published in the Journal of Allergy and Clinical Immunology has found.

Parasitic roundworms live inside the body, typically the gut, causing things like fever and diarrhoea. At least 800 million people worldwide contract ascaris lumbricoides infection each year, with roundworms most common in countries with a warm, tropical climate.

But the new research, undertaken by an international team of experts from the universities of Birmingham, Bergen and Cape Town suggests that Europeans encounter the parasite more than experts previously thought.

The researchers studied 671 adults from Norway, Estonia, and Denmark. They discovered 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.

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.”

The study, 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.”