Researchers may have gained some insight into why an attempt at xenotransplantation—animal-to-human organ transplant—failed earlier this year. David Bennett, Sr., died in March, just two months after receiving a pig heart in a transplant. It was a groundbreaking experiment with a tragic end for Bennett and his family. On Thursday, doctors from the University of Maryland revealed an unwelcome surprise. The heart they had transplanted into the patient contained viral DNA. The pig had been carrying porcine cytomegalovirus.

Testing prior to the transplant did not show any active infection in the donor pig. Doctors thought the procedure would be safe. But one major worry about xenotransplantation is the risk that it could introduce new kinds of infections into humans.

Some viruses are latent. That means they lurk within an organism—animal or human—without causing symptoms or disease. But latency doesn’t mean they can’t be transferred—where they could activate and cause problems.

Dr. Muhammad Mohiuddin is scientific director of the university’s xenotransplant program. He says development is under way of more sophisticated tests to “make sure that we don’t miss these kinds of viruses.”

The animal virus was first reported by MIT Technology Review. It cited a presentation given to the American Society of Transplantation last month by Dr. Bartley Griffith. Griffith is the surgeon who performed Bennett’s transplant.

The field of xenotransplantation is fraught with scientific challenges and ethical concerns. People of all ideological backgrounds—Christians included—wrestle with the idea of using animals as donors for human transplants. While human life is clearly of great value to God—more so than animal life—all creatures do have value and must be treated humanely. Beyond the animal care issue, some question whether it is even inappropriate to combine the God’s-image nature of humanity with the clearly creaturely physical components of the animal population. Is xenotransplantation going too far with the creation order—or is it a merciful application of the sameness of materials and patterns of development that God designed into His creation, perhaps for the purpose of using animals to save human life?

While the ethics debates continue, doctors likewise press on. They have tried using animal organs to save human lives for decades without yet a complete success.

At this point, no one is certain the virus was the cause of Mr. Bennett’s demise. Griffith said his patient, while very ill, had been recovering fairly well from the transplant. But then one morning, he woke up with symptoms similar to an infection. Doctors ran numerous tests. They gave Bennett a variety of antibiotic and antiviral medications and an immune-boosting treatment. But the pig heart become swollen and eventually quit functioning.

“What was the virus doing, if anything, that might have caused the swelling in his heart?” Griffith asks. “Honestly we don't know.”

Teach us to number our days that we may get a heart of wisdom. — Psalm 90:12

(David Bennett, Jr., stands next to his father’s hospital bed in Baltimore, Maryland, on January 12, 2022, five days after doctors transplanted a pig heart into Bennett, Sr., in a last-ditch effort to save his life. University of Maryland School of Medicine via AP)