Blood Screening FAQs

Why are blood banks screening for Trypanosoma cruzi infection, the parasite that causes Chagas disease?

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.

How does the screening test protect people from Chagas disease?

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

What happens to the blood that tests positive on the screening test?

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

Will I be tested automatically?

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.

If my blood tests positive on the screening test, does that mean I have Chagas disease?

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.

What does a “false-positive” result mean?

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.

Will the blood bank let me know if my blood tests positive for T. cruzi infection?

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

Can I get Chagas disease from donating blood?

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.

Can Chagas disease be spread through blood transfusions?

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

If I test positive for T. cruzi infection, can I give blood again?

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.

If I was diagnosed with Chagas disease in the past, can I donate blood?

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

If I have had a transfusion or a transplant, should I be concerned about getting Chagas disease?

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.

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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: September 16, 2020