By Jonathan Amos

BBC News science reporter, Dublin



Dr Padraic Fallon, from Trinity College Dublin, and colleagues have already managed to cure asthma in lab mice by infecting them with the tiny creatures. The team now has to explain how the parasites achieve this feat at a molecular level.

If they can do that, they should then be able to synthesise a new drug compound to treat asthma in people.

On the rise

Asthma and other allergies have increased almost threefold over the last 30 years in many developed countries, including Ireland and the UK.

We believe that this research will lead us to develop a new ways of preventing and treating asthma

Dr Fallon, Trinity College Dublin

The thinking behind this theory is that people living in modern industrialised societies are no longer exposed to the pathogens, such as viruses and bacteria, they would have been in the past, and so their bodies react to other, more minor threats.

"In Africa, for example, the immune system is too busy chasing after worms to bother going after house dust mites," explained Dr Fallon.

"In a developed society, the immune system is looking for things to respond to.

"It's evolved to see worms and suddenly there are no worms there. So suddenly house mites, peanuts - whatever the allergies are - occupy the immune system and it responds and causes disease," he told the British Association's Festival of Science in Dublin.

In a study in Gabon, Africa, schoolchildren that were infected with worms had lower allergic responses to house dust mites than children with no worms.

When the children had their worms removed by drugs they then developed increased allergic responses.

Red blood cells

The particular worm in question, the schistosome, is the cause of bilharzias, or schistosomiasis.

As the worms feed on red blood cells and dissolved nutrients such as sugars and amino acids, they can cause anaemia and fatigue, and in some cases the victim passes red urine, tinted by blood lost through the damaged kidneys.

It is thought that around 250 million people are infected with bilharzia in the tropics.

Dr Fallon says the worm has clearly evolved a way to control the human immune system, raising and lowering inflammation in its host to just the right level to ensure its parasitic lifestyle can be maintained.

The trick now, he says, is to learn how the worm does this so that the knowledge can be applied to allergic diseases.

"We believe that this research will lead us to develop a new ways of preventing and treating asthma and anaphylaxis, which can then be extended to treat inflammatory bowel disease and arthritis," Dr Fallon said.