Worm clue to asthma treatments
05 September 2005

Parasitic worms may hold the clue to developing future asthma treatments, claimed Irish scientists today.

Dr Padraig Fallon and a team at Trinity College Dublin found that mice who were susceptible to asthma and who were infected with a parasitic flatworm called Schistosoma mansoni (pictured) did not suffer the same breathing difficulties as mice with asthma who did not have the worm.

They believe that there is a protein in the parasite that blocks inflammation, which causes asthma symptoms. Identifying and replicating this protective mechanism could lead to the development of new treatments for asthma and other diseases.

The Schistosoma mansoni occurs in tropical countries and causes an infection called bilharzia. The worm grows inside blood vessels and produces hundreds of eggs a day, feeding on red blood cells and dissolved nutrients such as sugars and amino acids. If untreated - as it rarely is in the countries where it is prevalent - this can cause liver damage, anaemia and resistance to other diseases. It is thought that more than 200 million people have the condition: however, they do not have asthma.

Exposure to parasites may help build immune system

This bears out the view held by some scientists who believe that exposure to bacteria and parasites in early life could help people to develop an effective immune system, and that the sharp rise in asthma and allergies in modern, sanitised societies could be explained by our reduced contact with parasites and bacterial infections.

Scientists in the US have used a parasite called a whipworm to treat inflammatory bowel disease, and research funded by Asthma UK at the University of Nottingham is currently investigating the incidence of asthma and allergy in children in Vietnam who have hookworm.

'The link between increased asthma and allergy in the western world and decreased parasitic infections is an intriguing one,' confirmed Dr Lyn Smurthwaite, Asthma UK's Research Development Manager. 'Seventy-five per cent of people with asthma tell us their symptoms are triggered by allergies.'

'No one is suggesting infecting people with worms as a cure,' she added. 'However, by understanding how the worms protect the mice from developing breathing difficulties, the researchers at Trinity College may be taking exciting first steps towards developing new asthma treatments. Asthma UK looks forward with interest to the results of further research in this area.'

Dr Fallon presented his findings at the British Association for the Advancement of Science festival in Dublin.