An investigation into the death of the first person to receive a heart transplant from a pig has discovered that the organ had an animal virus, but it's not clear if the virus was a factor in the patient's death, University of Maryland Medical Center doctors say.
They found viral DNA inside the pig heart transplanted into 57-year-old David Bennett Sr., 57, who received the heart in January and died in March, but said there was no indication that the virus, called porcine cytomegalovirus, was causing an active infection, the Associated Press reported.
The heart came from a pig genetically modified to lower the risk that Bennett's immune system would reject it.
The donor pig was healthy, passed required U.S. Food and Drug Administration testing for infections, and was raised in a facility designed to prevent animals from spreading infections, the University of Maryland doctors said.
The company that provided the pig, Revivicor, would not comment to the AP.
Bennett had been recovering fairly well from the transplant but then developed symptoms similar to an infection, according to Dr. Bartley Griffith, the surgeon who performed the groundbreaking transplant.
Bennett was given antibiotics, antiviral medication and a treatment to boost his immune system, but the pig heart became swollen and eventually stopped working.
"What was the virus doing, if anything, that might have caused the swelling in his heart?" Griffith told the AP. "Honestly we don't know."
He said this didn't appear be a typical organ rejection, and the investigation into Bennett's death is continuing.
A major concern about animal-to-human transplants is the risk of new kinds of infections being passed to humans, according to the AP.
Visit the U.S. Food and Drug Administration for more on organ transplants from animals to humans.