A Swiss company is testing a hay fever drug that tricks the human immune system into acting as if it has been exposed to an infectious agent found in dirt.

Cytos Biotechnology has tested CYT 003-QbG10 on 10 people with hay fever and has found that their sensitivity to grass pollen is 1 percent after treatment to what it was before, New Scientist magazine reports. So far, the subjects have been free of hay fever for eight months.

A previous study found that people who are sensitive to dust mites have remained free of symptoms for at least a year.

The drug mimics the effect of exposure to mycobacteria, which somehow reboots the immune system, New Scientist said.

Copyright 2006 by United Press International