Corixa Corp has presented evidence to the U.S. Food and Drug Administration (FDA) showing that one of its proprietary recombinant antigens may be useful for screening the nation's blood supply for the potential presence of a deadly parasite known as Trypanosoma cruzi (T. cruzi).

The FDA has recognized the potential for introduction of T. cruzi into the U.S. blood supply, and is interested in the development and evaluation of tests that can be used to prevent transmission by transfusion of blood or blood products.

T. cruzi causes Chagas' disease, a chronic infection that primarily affects the nervous system and heart, causing severe neurological disorders, as well as swelling or denervation of nervous tissue in the heart, colon and esophagus. The organism can circulate in the blood for many years after infection, and can lead to transfusion-acquired infection if blood from an infected donor is transfused into a recipient.

"In studies to date, the TcF recombinant antigen has been able to detect nearly all patients infected with T. cruzi, and avoids many of the problems of false positivity and unreliability associated with older assays that used whole organisms for antibody detection," said Dr. Persing. "Testing for this antibody could be an important step toward protecting our nation's blood supply from this dangerous contaminant."

Chagas' disease often goes undiagnosed because its symptoms are also associated with heart disease and a variety of other disorders. In about one-third of acute cases, a chronic form of the disease develops some 10-20 years later, causing irreversible damage to the heart, esophagus and colon. Patients with severe Chagas' disease become progressively more ill and ultimately die, usually from heart failure. According to the World Health Organization, Chagas' disease is endemic in 21 countries, with 16 million-18 million people infected and 100 million more at risk. Contaminated blood transfusions are suspected to be the primary way in which the parasite has been transmitted to industrialized countries.