U.S. Blood Donations Test Positive for Chagas Disease

Blood donations in 34 states have tested positive for Chagas disease, a potentially deadly parasitic infection, in the last 10 months, according to the American Association of Blood Banks. The Red Cross is investigating four cases that may have transmitted via blood transfusions, and nine possible cases of insect-to-human transmission that may have occurred in the United States.

The 241 donations that tested positive mean that the donors may have been exposed to the parasite that causes the infection. The greatest number of positive donations have been found in California, Florida and Texas.

"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," International Health Division M.D. Director James H. Maguire said in a press release.

People acquire the disease most commonly through a bite from an insect carrying the parasite that causes the disease. People also become infected by consuming uncooked food that is contaminated, blood transfusion and organ transplantation, according to the Centers for Disease Control Web site.

Chagas begins in an acute phase where a person may or may not exhibit certain symptoms, which include fever, fatigue, body aches, headache, rash, etc., according to the CDC's Web site. In the chronic phase, cardiac complications, such as an enlarged heart, heart failure, and/or intestinal complications, including enlarged esophagus or colon, occur.

The CDC estimates that 8 million to 11 million people in Mexico, Central America and South America are infected with the disease, and most don't know they're infected.

Two treatments exist for Chagas, and the most effective is the antiparasitic treatment for cases that are discovered early.

The U.S. Food and Drug Administration approved blood screening for Chagas' disease in December 2006. About 70 percent of blood donations in the United States are screened for Chagas' with a test that's 99 percent accurate, according to the FDA Web site.