Hidden Threat: Blood Banks Only Test New Donors for Chagas Disease

After passing Chagas test, blood donors aren’t subsequently screened for the T. cruzi parasite, Chagas disease

An NBC 5 investigation is raising new questions about the safety of the blood supply here in Texas.

Kissing Bugs have infected at least a dozen people in Texas with a dangerous parasite, Trypanosoma cruzi, which causes Chagas disease. NBC 5 Investigates has learned T. cruzi can also be transmitted through blood transfusions.

NBC 5 Senior Investigative Reporter Scott Friedman teamed up with The Dallas Morning News’ Dr. Seema Yasmin and found the current standards for blood screening may not be enough after learning blood banks don’t test every donation for the potentially deadly parasite.

If you or someone you love needs a blood transfusion, you want to know the blood is safe. Under the current guidelines, one expert fears there’s a back door open to concern.

"I’m concerned and I think there should be more general concern than there seems to be,” said Dr. Richard Benjamin, the former head of blood safety for the American Red Cross.

His concern stems from Kissing Bugs.

As NBC 5 Investigates first reported, the bugs have infected at least a dozen people in Texas with a dangerous parasite that causes Chagas disease. Thousands of others in Texas are living with the parasite in their blood after being infected outside the United States.

Most people live for years without knowing they’re infected because initial symptoms are similar to the flu. The parasite then lies dormant in the body for decades before possibly causing heart failure or even death.

The parasite can also be passed on through blood transfusions.

Guidelines from the Food and Drug Administration advise only first-time blood donors need to be tested for Chagas. So if a donor is clear on the first test, they can come back and donate again and again without ever being retested. Chagas is the only disease in the U.S. where donors are tested just once for the disease.

“It’s time to consider Chagas again and see if what we are doing currently is correct or not,” said Benjamin.

Benjamin now works for Cerus, a company that makes technology that can inactivate Chagas and other pathogens in donated blood. It’s already in use in Europe and soon at the National Institutes of Health.

But Texas blood banks don’t have that technology yet, and without it Benjamin believes the FDA should consider mandating Chagas testing for each donor, every time they give blood.
Especially in places like Texas.

“I think we have enough experience now with the testing that we really should look at doing things differently where the risks are higher,” said Benjamin.

Benjamin said testing only first-time donors may be fine in some parts of the country but may not be in Texas where Kissing Bugs are known to exist and could infect a person in between blood donations.

Research at Baylor Medical School suggests many donors who test positive in Texas were infected in Texas.

“We’re finding that more than half of our blood donors actually acquired their infection here, which placed a lot of concern on our minds as to what the real risk is,” said Dr. Kristy Murray, a researcher with Baylor Medical School.

But blood banks NBC 5 Investigates spoke with said they’re not concerned.

“The screen that we have in place is protecting the blood supply,” said Dr. Lauri Sutor.

Kissing Bug Occurrences in Texas

Explore the locations and seasonality of kissing bugs in Texas. Map courtesy of Texas A&M University.

Sutor is the vice president of medical and technical services for Carter Blood Center, the largest blood bank in Texas.

Souter said there’s no need to test donors for Chagas each time.

“I think the average person watching this is going to say, ‘Why wouldn't they do this, just to make sure I'm protected?’" Sutor said. “There's (Pauses). What we do now is doing the job.”

The FDA reports only seven people in United States and Canada have been infected with Chagas after receiving blood in the U.S. and Canada and that there are no infections since the first-time donor testing began in 2007.

Sutor said that shows the current system is working.

She worries more testing would lead to more false positives which forces blood banks to throw away perfectly good blood.

“It's only going to make my donors upset. It's only going to lose us more blood. We already have days when we have to work very hard to have enough blood,” said Sutor.

The FDA, which sets rules for blood banks, declined to be interviewed for this story but in an email wrote, ”The FDA, DCD and NIH are continuing to monitor the threats to blood safety posed by Chagas disease.”

In the FDA’s most recent guidance paper on the issue, notes the scope of the problem “…in the U.S. continues to be uncertain because of the limited number of studies conducted to date.”

Texas’ Department of State Health Services said it stands by the FDA’s decision.

“So we're not going to second guess them, especially in light off the success that's been documented since the testing began in 2007,” said Tom Sidwa, state public health veterinarian with the Texas Department of State Health Services.

The American Red Cross agrees, saying the risk of Chagas infections is “…the same risk level that we accept for HIV.”

The American Association of Blood Banks says since first-time donor testing began the rate of Chagas passed through transfusions “was less than 1 percent.”

Candace Stark contracted Chagas in Texas and first found out when she went to donate blood.

She can’t believe blood banks aren’t testing each donor every time and think they need to change their policy. She doesn’t want anyone else to end up with this silent killer in their body if more can be done to keep that from happening.

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