Trails of human bacteria from sneezing and coughing preserved on Mount Everest: study

In this May 22, 2019, file photo, a long queue of mountain climbers line a path on Mount Everest just below camp four, in Nepal. (AP Photo/Rizza Alee, File)

Even at thousands of metres high, germs are inescapable, according to new research at the University of Colorado Boulder.

Near the world's tallest peak above sea level at Mount Everest, researchers detected human-associated microbes from coughing and sneezing that could potentially have been leaving trails of human bacteria for centuries.

The study, published in the peer-reviewed Arctic, Antarctic, and Alpine Research journal, analyzed samples from the South Col, at 7,925 metres high, where nature explorers set up their final camp before climbing up to the mountain's peak. Researchers were able to find microbial DNA related to humans like staphylococcus, which can cause staph infections and food poisoning. They also found streptococcus bacteria, which is often associated with strep throat.

“There is a human signature frozen in the microbiome of Everest," said one of the researchers and professor of of ecology and evolutionary biology, Steve Schmidt, in a news release.

By using gene-sequencing technology to conclusively verify the DNA samples on both dead and living microbes, the researchers were surprised to find bacteria that normally live in warm and wet environments like the human nose and mouth able to withstand the frigid, harsh conditions on the mountain.

Additionally they were able to find organisms previously found in the Andes and Antarctica, including a genus of fungi called Naganishia, which can endure freezing temperatures and UV radiation. While most microbes don't survive the cold terrain and high UV light on the mountain, researchers believe Naganishia may still be able to grow with water and sunlight to have just enough heat to survive.

This isn't the first time trails left by humans have made a mark on the famous mountain trail. The increasing amount of tourism has also increased the amount of trash left behind by climbers as some struggling to complete the climb often leave behind their tents when it's too cold or difficult to dig out, or let their human waste fall into crevasses on the mountain.

There is also concern for climate change's effect on the mountain as melting glaciers have caused the popular starting point of the trek at the south base camp to move further down after 2,000-year-old ice began to melt.

The researchers hope their findings will not only help us understand how humans can further impact the planet's environment but potentially how humans can affect the environment on other planets and moons.

“We might find life on other planets and cold moons,” Schmidt said. “We’ll have to be careful to make sure we’re not contaminating them with our own.”