A Worm a Day Keeps Asthma at Bay

A nice little parasite may be helping
asthma patients: the schistosome
© NCI Visuals Online

“The reasons for the dramatic recent increase in allergic diseases are complex,” says Dr Padraic Fallon from the Department of Biochemistry at Trinity College Dublin. “We believe a major factor is the reduction in parasitic worms, and bacterial or viral infections, in modern ‘clean’ societies.”

Studies have shown that people in developing countries have fewer allergies. 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.

The particular worm in question, the schistosome, is the cause of Bilharzia. 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.

Allergies are caused when the immune system responds to allergens, such as peanuts, dust mites and cats. This immune response can stimulate allergic diseases, including eczema, anaphylaxis and asthma. Infections with parasitic worms also induce this particular immune responses and it is argued that this type of immune response was not designed to cause allergies, but evolved to control worm infections. In modern societies where there are no longer parasitic worms present, the immune system responds to other common allergens, such as cats, and induces allergies.

The objective of Dr. Fallon and his colleagues’s research is to use molecules from the schistosome worm to treat or prevent diseases, such as asthma and inflammatory bowel disease. His group has shown that when transgenic mice, engineered to have a high susceptibility to anaphylaxis and asthma, were infected with the worm they developed resistance to anaphylaxis.

“We believe that this research will lead us to develop a new ways of preventing and treating asthma,” says Fallon.

MEDICA.de; Source: British Association for the Advancement of Science