Bacteria resistant to all antibiotics have arrived in Europe, and experts fear it could be the start of a global epidemic of untreatable infections.

Last month, we reported on a gene mutation called MCR-1 that had shown up in bacteria in China. The mutation is resistant to all antibiotics, including colistin, a last-resort drug used to tackle tough bacteria when all other antibiotics have failed.

The superbugs were found in 15% of raw meat samples in China, as well as a fifth of the animals tested. Colistin had also failed in 16 patients infected with drug-resistant infections.

Now a patient in Denmark has been diagnosed with an untreatable form of salmonella, scientists from George Washington University (GWU) and the Statens Serum Institute (SSI) and National Food Institute (NFI) in Denmark announced Friday. In addition, they also found untreatable bacteria in 5 samples of chicken imported from China through Germany.

The Antibiotic Resistance Action Center in the Milken Institute School of Public Health at GWU, said in a statement to National Geographic:

“The news that the dangerous colistin resistance gene has been found in Denmark is alarming. This newly identified gene, called MCR-1, is on a mobile piece of DNA that can make copies of itself and then jump to from bacterium to bacterium, spreading resistance. History shows that these mobile resistance genes can spread around the world quickly, silently riding in people, animals, and food. The news that MCR-1 has been discovered in Denmark suggests that this scenario is playing out in real time.”

The Danish researchers said that when they learned of the new resistance factor, they immediately took a look at the stored genomes they held at their institutions to look for it:

“The approximately 3,000 Gram-negative (E. coli or Salmonella) bacteria, which have previously been mapped using whole genome sequencing, have been reexamined to see whether MCR-1 is present. Results show that MCR-1 was found in one patient, who suffered from a blood infection in 2015 and in five food samples that have been imported from 2012-2014. All the bacteria are multi-resistant ESBL bacteria containing the MCR-1 gene, which can further complicate treatment.”

The Chinese researchers who discovered the untreatable pathogens warned that it could spread globally, but experts are shocked at how quickly they’re making their way around the globe, saying the situation is extremely serious.

And bacteria affected by the MCR-1 gene are especially frightening because they can be transferred to other types of bacteria, which means they could spread quickly between animals and humans.

Professor Frank Møller Aarestrup, a microbiologist at the Technical University of Denmark, said today: “This is a very alarming discovery. It is something I had feared, but hoped I would not see.”

Aarestrup said he wouldn’t be surprised if the powerful bugs had already migrated to the U.K. Scientists in New Zealand said the same.

“History shows that these mobile resistance genes can spread around the world quickly, silently riding in people, animals, and food,” said Dr. Lance Prince of GWU. “The news that MCR-1 has been discovered in Denmark suggests that this scenario is playing out in real time.”

Colistin is widely used in farming, particularly in China, where farmers feed it to pigs and chickens en masse to fatten them up. In the U.S., approximately 70% of antibiotics considered vitally important to human health are used in farm animals.

Drug resistance hasn’t become enough of a problem in the U.S. to start using colistin, but it’s only a matter of time until it’s needed. And then, surely, it will only be a matter of time until colistin stops working for Americans.

The GWU ended its statement by saying this:

“We must act swiftly to contain the spread of colistin-resistant bacteria, or we will face increasing numbers of untreatable infections. Leaders from every nation should immediately implement a ban on the use of colistin in animal agriculture. While China appears to be the biggest user of the drug, it is approved for use in the European Union and many other countries. It also is approved for use in food animals in the U.S., but drug companies holding those approvals are not actively marketing the drugs. Drug companies with these approvals should immediately withdraw these label claims to ensure that colistin is never used in U.S. animal agriculture, otherwise our livestock production facilities could become breeding grounds for untreatable superbugs.

In addition, we need to remember why colistin is the last drug available for treating these dangerous infections. We turned to it because the preferred drug class – carbapenems – became powerless against some superbugs due to overuse. Carbapenems are still effective against many bacteria, but for how long? While carbapenems are not approved for use in animal agriculture in many parts of the world, their use is not explicitly banned. World leaders should call for an immediate ban on carbapenems to protect them for future generations.”