A Maryland man who lived with a transplanted, genetically-modified pig's heart for two months may have died due to a virus that targets feral animals, The New York Times reported Thursday.

Dr. Bartley Griffith, a surgeon focused on transplants at the University of Maryland School of Medicine, performed the animal-to-human surgery on the patient, David Bennett Sr., and also reported the complication as the patient's health torpedoed.

The procedure initially had been deemed a success. It took place in January 2022, after the Food and Drug Administration had granted the university an emergency authorization for the transplant.

According to MIT Technology Review, it was the first genetically modified pig-to-human heart transplant. Opposition to these types of procedures is often focused on the fact that animal organs may help transmit novel pathogens to humans.

Ahead of the procedure, the pig's heart was altered in hopes that it wouldn't be rejected by the patient's immune system. Revivicor, a medicinal company specializing in regenerative products, provided the heart to Bennett.

Revivicor did not immediately return Insider's request for comment.

According to The Times, University of Maryland staff said the animal had been checked for viruses and porcine cytomegalovirus – the virus that scientists believe could have played a role in Bennett's death – was not actively detected before the procedure.

"It was either die or do this transplant. I want to live," Bennett said before the surgery, according to a UMMC press release. "I know it's a shot in the dark, but it's my last choice."

Bennett had a terminal heart condition and was not eligible for a human heart transplant due to human organ shortages and previously failing to follow doctor's orders, according to Griffith.

The University of Maryland said in a statement emailed to Insider there is "no evidence that the virus caused an infection in the patient or infected any tissues or organs beyond the heart".

"The cause of death of pig heart recipient David Bennett, Sr, is still being studied," a spokesperson for the university said. "Dr. Bartley Griffith, who led the xenotransplant surgical team, recently presented preliminary findings at a scientific conference where he noted that research continues into various potential causes."

"Among these potential causes was the patient's advanced state of heart failure before the transplant," the spokesperson continued. "Dr. Griffith also noted that they found evidence of a virus called porcine cytomegalovirus (pCMV) through highly sensitive special testing."

The university added that the heart "was tested just before shipment to Maryland, and just before the transplant a few days later", adding that FDA procedures were followed and that the pig was raised in a facility designed to prevent viral infections.

Bennett was in good health for the first month and a half after the procedure and the pig's heart functioned well. According to the MIT Technology Review, Griffith said a test result came back with the porcine virus after 20 days – albeit showing very little signs of spreading.

"So we started thinking that the virus that showed up very early at Day 20 as just a twinkle started to grow in time, and it may have been the actor – it could have been the actor – that set this all off," Griffith told other medical professionals, according to the report.

After 45 days, the patient's health tanked, and within days, on March 8, he died.

"At Day 45, he looked really funky," Griffith told scientists. "Something happened. He looked sick. He lost his attention. He wouldn't talk to us. He lay in bed breathing hard, and was kind of warm."

The procedure, although a significant animal-to-human organ transfer, could spell trouble in terms of viral transmissions between animals and humans during the operations.

This article was originally published by Business Insider.

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