FREI TEST

procedure used in the diagnosis of lymphogranuloma venereum, a venereal disease caused by a virus. The yolk of a chick embryo is infected with the virus, which is then inactivated by heat. A small amount of this commercial preparation is injected into the skin of the forearm. In a positive reaction, which indicates that the person tested has, or has had, the disease, an inflammatory nodule at least 6 millimetres (about 1/4 inch) in diameter with reddened skin around is usually present at the end of 48 hours.