Researchers trying to learn what killed the first person to receive a pig heart transplant have found the organ harbored an animal virus.
But University of Maryland doctors cannot yet say if the virus played any role in the man's death.
David Bennett Sr. died at age 57, two months after the groundbreaking experimental transplant.
His surgeon says the DNA of a pig virus was later found in the heart but no signs that the bug caused an active infection.
Still, a significant worry about animal-to-human transplants is the risk of spreading new infections.
If some viruses are “latent,” Bennett's surgeon Dr. Bartley Griffith said, “it could be a hitchhiker."
Dr. Muhammad Mohiuddin, the scientific director of the university’s xenotransplant program, says they would conduct more sophisticated tests to “make sure that we don’t miss these kinds of viruses."
The donor pig was healthy, passed infection testing required by the Food and Drug Administration, and lived in a facility to prevent animals from spreading infections.
Dr. Griffith said Bennett was recovering well after the surgery but one day woke up worse. Doctors gave him antibiotics due to symptoms similar to an infection, but nothing worked as the pig's heart began to swell, filled with fluid and eventually quit functioning.