Blood Screening FAQs

The transmission of Trypanosoma cruzi through blood transfusion is a recognized risk. Screening tests have been approved by the U.S. Food and Drug Administration. Screening for Trypanosoma cruzi infection makes the blood supply even safer for everyone.

The blood screening test allows blood banks to destroy potentially infectious blood before it is given to anyone.

The blood that tests positive will be removed from the blood supply.

Yes. In the United States, donors are tested once and if the result of their test is negative for T. cruzi infection, they will not be tested when they donate again at that blood bank.

Probably. However, no test is perfect and occasionally a test can give a “false-positive” result. You should discuss your results with your health-care provider.

A “false-positive” result is when test results look like a person has a disease, but further testing indicates the person does not have the disease after all.

Yes. The blood bank will contact you if you test positive for Trypanosoma cruzi infection and will provide general information about the disease.

No. You cannot contract Chagas disease from donating blood. The needles are only used once and are discarded. Sterile procedures and equipment are routine at blood banks.

Yes. The disease can be spread by receiving blood that came from a person with Chagas disease.

Maybe. You should contact the blood bank about possible retesting to see if you can donate blood again. In 2017, the U.S. Food and Drug Administration issued new rules about how donors who tested false positive can be evaluated to see if they are eligible to donate blood again. If you were diagnosed by your doctor, you cannot donate blood.

No. If you have ever been diagnosed with Chagas disease, you cannot donate blood.

Probably not. The risk is very low. You should, however, be aware of the potential risk for Chagas disease infection and the need to monitor your health. If you have symptoms of Chagas disease or other concerns you should contact your health-care provider.


This information is not meant to be used for self-diagnosis or as a substitute for consultation with a health-care provider. If you have any questions about the parasites described above or think that you may have a parasitic infection, consult a health-care provider.

Page last reviewed: April 8, 2019