It's easy to think of cold and isolated Antarctica as immune to some of the influences of humans, but that wishful thinking isn't how reality is playing out.

A study published in Science of the Total Environment suggests that human-linked pathogens — like Campylobacter jejuni, a common cause of food poisoning in the U.S. and Europe, and even a salmonella strain normally only seen in urban scavenging birds — have spread from people to seabirds.

Passing on the germs

Animals passing diseases to humans isn't anything new; Ebola, Zika and anthrax may come to mind. Try naming a disease that we have passed to other animals — especially ones that are exclusive in their transference — and you might find yourself drawing a blank. We can pass along influenza and mumps, according to Science Magazine, and some pathogens, like salmonella, are traded back and forth between humans and animals.

This process of humans passing pathogens to other animals is called reverse zoonosis. Earlier researchers suggested that this germ exchange wasn't something that happened in Antarctica, but the team behind this new study wasn't so sure. They collected fecal samples from 666 adult birds from 24 different species, including rockhopper penguins, Atlantic yellow-nosed albatrosses, giant petrels and skuas. Of course, when testing for pathogens, you want the cleanest poop possible, so scientists had to catch the birds and then clean them out with sterile swabs.

"Penguins are very strong … and skuas are extremely clever," Jacob González-Solís, an environmental and evolutionary biologist from the University of Barcelona who worked on the study, told Science Magazine. If you don't get a skua on the first try, good luck ever getting close enough for a second try, González-Solís added.

A South Pole skua stands on a dirty outcropping in Antarctica. A South Pole skua (Stercorarius maccormicki) stands on an outcropping in Antarctica. (Photo: DLR German Aerospace Center/Wikimedia Commons)

The process took from 2011 to 2014 and included birds on Livingston Island, off the Antarctic Peninsula; the Southern Ocean outposts of Marion Island and Gough Island; and the Falkland Islands, a key point along many of the birds' migration routes. Once analyzed, the researchers found the previously mentioned C. jejuni and salmonella as well as C. lari, another bug noted for causing gastric pain and distress in humans. The C. lari strain showed resistance to human and veterinary antibiotics, suggesting it had made a leap from humans to the avian species.

Researchers aren't sure how the birds came into contact with the diseases.

"There are various possibilities, the most likely is contact between Antarctic and sub-Antarctic fauna with domestic birds in sub-Antarctic communities such as the Falklands, but they could also be the legacy of old whaling missions, Antarctic research stations and the growth in Antarctic tourism," González-Solís told CNN.

A rockhopper penguin on the Falkland Islands Researchers found pathogens in rockhopper penguins. (Photo: Giedriius/Shutterstock)

The birds are likely not in danger as the researchers could not find any instances of them dying from the pathogens. But there's still reason to be concerned: The fact that the pathogens are appearing at all means that other, more dangerous pathogens could cause problems for their populations.

"These Salmonella and Campylobacter strains, which are a common cause for infections in humans and livestock, do not usually cause death outbreaks in wild animals," the study's lead author Marta Cerdà-Cuéllar said in a statement. "However, the emerging or invasive pathogens that arrive to highly sensitive populations — such as the Antarctic and Subantarctic fauna — could have severe consequences and cause the local collapse and extinction of some populations."

To that end, the researchers recommend stricter biosecurity measures for scientists working in Antarctica and tourists visiting the birds, including carrying home human waste.

Are humans making penguins sick?
Human-based pathogens are showing up in penguin poop, and that could spell serious trouble for the Antarctic birds.