ANAHEIM, Calif. -- In the 10 months since the Food and Drug Administration (FDA) licensed the first blood-screening test for Chagas' disease, some 241 blood donations in the United States have tested positive, indicating donor exposure to the parasite known to cause this serious and potentially fatal parasitic infection, according to data released today at the annual meeting of American Association of Blood Banks (AABB). The test is manufactured by Ortho-Clinical Diagnostics, Inc.
Chagas'-positive donations have been reported in 34 states with the highest concentration in California, Florida and Texas, according to data compiled by the AABB.
During presentations at the conference today, blood safety experts also said they are investigating new cases of transmissions of Chagas' disease that may have occurred through blood transfusions and via insect bites from bugs known to carry the parasite. Such cases have been extremely rare, or have gone undocumented, in the United States. Dr. Susan Stramer, executive scientific officer for the America Red Cross, said blood safety experts are investigating 20 cases of possible insect-to-human transmissions with strong evidence suggesting that nine cases may have occurred in the U.S. Also, the Red Cross is investigating four possible transmissions via blood transfusions. Details of these cases were not disclosed.
"While we have known that Chagas' disease was present in North America, the numbers of Chagas'-positive blood donations, as well as new reports of transmission of infection to persons from bugs, are surprising," said James H. Maguire, M.D., director, International Health Division, University of Maryland School of Medicine. Maguire is the former chief of the parasitic diseases branch at the Centers for Disease Control and Prevention (CDC).
The American Red Cross was among the first blood collection agencies in the U.S. to begin testing donations for Chagas' in late January, following FDA approval of Ortho's blood-screening test in December 2006. Today, approximately 70 percent of all blood donations in the U.S. are now being screened for Chagas'.
"Ensuring the safety of the blood supply is a major public health priority, and one that our company is proud to play a role in," said Cliff Holland, worldwide president of Ortho-Clinical Diagnostics, Inc. "Screening blood donations for Chagas' reduces the risk of spreading this disease through blood transfusions."
In additional developments, public health authorities in Arizona have made Chagas' a "reportable" disease. Three southern states are considering similar action. A reportable disease is one that must be reported to federal, state, or local health officials when diagnosed, such as active tuberculosis, hepatitis, gonorrhea and HIV, for example.
Also called American trypanosomiasis, Chagas' disease is an infection caused by the blood-borne parasite Trypanosoma cruzi, or T.cruzi. The disease is endemic to most countries in Central and South America, as well as Mexico. Transmission occurs through insect bites, blood transfusions, organ transplants and via infected pregnant women to children in utero. Early infection is usually mild and unrecognized, but persists lifelong and may lead to organ damage, particularly of the heart and esophagus, causing an estimated 50,000 deaths annually worldwide. Infection also can be severe in people whose immune systems are suppressed, such as organ transplant recipients. According to the CDC, as many as 8 million to 11 million people in Mexico, Central America and South America have Chagas' disease. (1) Most do not know they are infected. Chagas' disease can be treated successfully if detected soon after the infection occurs, but there is no cure once the disease has entered the chronic stage.
In December 2006, Ortho-Clinical Diagnostics received FDA approval for the ORTHO(R) T.cruzi ELISA Test System. The test detects antibodies to the Trypanosoma cruzi parasite. In clinical trials, the ORTHO(R) T.cruzi ELISA Test System demonstrated 100 percent sensitivity with parasite positive and serological positive populations, and demonstrated an observed specificity of greater than 99.99 percent. When the FDA approved the test, the agency said: "This new test identifies infected donors and therefore can reduce the risk of disease transmission through blood transfusion or organ transplantation."
The company will seek FDA approval to expand use of its test for Chagas' disease in tissue and cell transplants (cadaveric testing) and for general diagnostic purposes.
Reference: (1) Updated CDC estimates as of March 2007. Earlier CDC estimates said the number of people infected with Chagas' disease worldwide ranged from 16 million to 18 million. Experts suggest that the decline may be attributable, at least in part, to effective prevention and intervention programs initiated in central and south America
Source: Ortho-Clinical Diagnostics, Inc.