Asthma is on the increase and scientists are at a loss to know why. There has been a four-fold rise in reported cases around the world over the past 25 years. In Ireland one in seven children and one in 20 adults are diagnosed with the disease.
There may be many more undiagnosed cases in Ireland, however, according to a specialist in the field, Dr Stephen Lane, consultant in respiratory medicine at Tallaght Hospital.
A recent international survey published in the Lancet, which included surveys of 3,000 Irish children, found that one in three children here reported symptoms consistent with asthma, ranking Ireland fourth in the world in this survey.
Researchers believe that environmental rather than genetic factors are driving up the incidence of asthma, Dr Lane said, given the rapid increase over such a short period. And there is now mounting evidence that asthma should not be considered just one disease.
While symptoms are very similar, there is a variety of disease mechanisms at work, given the variability in severity and patient response to different treatments, Dr Lane explained.
"Research into asthma is bedeviled because it is now believed that there are different forms of asthma. The whole basis of the research into the disease is trying to delineate the different forms of asthma at the biochemical level," he said.
Dr Lane has conducted important research into the most severe forms of asthma, involving the 1 to 5 per cent of cases that are "really difficult" to treat.
These patients do not respond to the steroid treatments which work well in the majority of cases. Dr Lane was "trying to find out why steroids are not working in these patients".
He has studied the disease for the past 10 years at Guy's and St Thomas's hospitals and the National Heart and Lung Institute in London and now continues this work at Tallaght Hospital.
He has isolated a specific protein that activates symptoms in the most severe cases, and he recently published his findings in the Journal of Clinical Investigation.
The symptoms associated with asthma - wheeze, chest tightness, shortness of breath and cough - are caused by the inflammation of the airways in the lungs. This is associated with the infiltration of white blood cells, eosinophils and lymphocytes into the airway walls. White blood cells fight infection but in asthma an abnormally high number migrate into the airways and in turn cause inflammation.
Dr Lane's findings open up important treatment possibilities for patients with the worst forms of asthma. He cautioned, however, that these were still some time off and much more work was needed before the introduction of new therapies. He is continuing his research and is in the process of setting up an asthma allergy centre which will take patient referrals from GPs.