Scientists have found a rare and frightening superbug gene on a U.S. pig farm and say their discovery suggests raw meat could carry the dangerous germs into the human population.

However, they have also confirmed that no pigs prepared for the slaughter carried the mutant gene. The researchers also stressed, that they haven’t found any threat to people as yet since none of the pigs are sick.

But the mutant gene should not have been on the farm at all and they have no idea how it got there.

“It is an extremely rare gene. How it got on this farm, we don’t know,” said Thomas Wittum, chair of the veterinary medical group at The Ohio State University, who led the study team.

The gene is called bla IMP-27, and it gives bacteria the ability to resist the effects of a class of antibiotics called carbapenems.

These breeds of chemicals are considered an antibiotic of last resort, so germs that resist their effects are very difficult to kill.

Worse, this superbug gene is carried on an easily swapped bit of modified material called a plasmid, and the researchers found it in several different species of bacteria on the farm. That suggests the bacteria have been passing the gene around.

The worry is that the gene will get into bacteria that infect people, a type of antibiotic-resistant germ called carbapenem-resistant Enterobacteriaceae, or CRE, are especially harmful.

If they get into the bloodstream and cause an infection, the CRE germs will kill half of their victims.

Just this summer researchers sounded the alarm about a drug-resistant E. coli sample containing a gene called mcr-1. It was also carried on a plasmid, and the fear is such an E. coli bacteria with the mcr-1 gene could pass it to another superbug with other mutations – producing a truly super superbug that can resists all known antibiotics.

Thomas Wittum and his team have also warned that omething similar could potentially happen with the bla IMP-27 gene found at the pig farm.