Throughout the history of our planet, peoplecoexisted with bacteria and viruses. We looked for ways to resist the bubonic plague and smallpox, and in return they looked for ways to infect us. We have been using antibiotics for almost a hundred years since Alexander Fleming discovered penicillin. In response to this, bacteria have acquired antibiotic resistance. There is no end to the battle. We spend so much time with pathogens that, in turn, we lead each other into a dead end. However, what happens if we suddenly encounter deadly bacteria and viruses that we have not seen for thousands of years or have never seen before?
In August 2016, in a remote corner of the Siberian tundra, on the Yamal Peninsula, a 12-year-old boy died and at least twenty people were hospitalized after anthrax infection.
It has been suggested that over 75 yearsago, a deer infected with anthrax died and its frozen skeleton was trapped under a layer of frozen soil, under permafrost. He stayed there until the summer of 2016, when permafrost thawed due to intense heat. Thus, she released a deer corpse and anthrax infection into the nearest water and soil, and then into the food supply. People are at risk.
The scary thing is that this may not be a solitary case.
Earth heats up and thaws more eternalpermafrost. Under normal conditions, the surface layers of permafrost with a depth of about 50 centimeters thaw every summer. But global warming is gradually exposing the old layers of permafrost.
Frozen perennial soil is an ideal place forkeeping bacteria alive for extended periods of time, possibly millions of years. This means that melting ice could potentially open Pandora's box of diseases.
The temperature in the Arctic Circle is growing rapidly, about three times faster than in the rest of the world. Other infectious agents may come out.
“Permafrost is an excellent keeper of germs andviruses because it’s cold, dark and free of oxygen, ”says evolutionary biologist Jean-Michel Claveri from Aix-Marseille University in France. "Pathogenic viruses that can infect animals and plants could be stored in old permafrost layers, including those that caused global epidemics in the past."
At the beginning of the 20th century alone, more than a million northerndeer died from anthrax. It is not so easy to dig deep graves in the north, so most of these carcasses were buried close to the surface, in 7,000 scattered burials in northern Russia.
What else could be hiding under frozen soil?
People and animals were buried in permafrosthundreds of years, so it’s quite possible that other infectious agents may come out. For example, scientists discovered RNA fragments of the Spanish influenza virus in corpses massively buried in the tundra of Alaska. Smallpox and bubonic plague are also buried in Siberia. In a 2011 study, Boris Revich and Marina Podolnaya wrote: "As a result of permafrost thawing, vectors of deadly infections of the 18th and 19th centuries can return, especially near cemeteries where the victims of these infections were buried."
A serious epidemic took place in Siberia in the 1890ssmallpox. One city has lost up to 40% of its population. The bodies were buried under the upper permafrost layer on the banks of the Kolyma River. After 120 years of floods, the Kolyma began to destroy the coast, and the melting of permafrost accelerated this process of erosion.
In a project that began in the 1990s, scientistsfrom the State Scientific Center for Virology and Biotechnology in Novosibirsk, the remains of Stone Age people discovered in southern Siberia, in the region of Gorny Altai, were studied. They also studied samples from the corpses of people who died during viral epidemics in the 19th century and were buried in the permafrost of Russia.
Scientists say they found bodies with ulcers characteristic of smallpox traces. Although they did not detect the smallpox virus itself, they found DNA fragments.
Of course, this is not the first time that bacteria frozen in ice come back to life.
In a 2005 study, NASA scientists successfullythe bacteria that had been imprisoned in a frozen pond in Alaska for 32,000 years were revived. Microbes called Carnobacterium pleistocenum have been frozen since the Pleistocene, when woolen mammoths still roamed the earth. As soon as the ice melted, they again began to swim as if nothing had happened.
Two years later, scientists managed to revive the bacterium8 million years old, which slept in the ice beneath the surface of a glacier in the Beacon and Mullins valleys in Antarctica. In the same study, bacteria were recovered from ice that was over 100,000 years old.
However, not all bacteria can return to life.after freezing in permafrost. Anthrax bacteria can do this because they form extremely hardy spores that can live in a frozen state for a very long time.
Other bacteria that can formdisputes, and therefore surviving in permafrost, include tetanus and Clostridium botulinum, responsible for botulism: a rare disease that can cause paralysis and lead to death. Some mushrooms can also survive in permafrost for a long time.
Some viruses can also survive for long periods of time.
In a 2014 study, scientists led byClavier revived two viruses captured by the permafrost of Siberia for 30,000 years. Known as Pithovirus sibericum and Mollivirus sibericum, they are considered "giant viruses" because, unlike most viruses, they are so large that they can be seen under a normal microscope. They were found at a depth of 30 meters in the coastal tundra.
Immediately after the rebirth, viruses became contagious. Fortunately for us, it is these viruses that infect only unicellular amoeba. However, research suggests that other viruses that can infect humans can also be resurrected.
Moreover, global warming is optionalmust melt permafrost to pose a threat. As Arctic sea ice melts, the northern coast of Siberia is easier to reach by sea. Obviously, its industrial development becomes more profitable, including the extraction of gold and minerals, the drilling of oil wells, and the production of natural gas.
“At the moment, these areas are empty and deepnobody touches the permafrost layers, ”Claveri says. “But these ancient layers can be obtained in the process of excavation and drilling. If viable virions still live there, it will be a disaster. ”
Giant viruses may be the most likely culprits of a viral outbreak.
“Most viruses quickly inactivate outsidehost cells due to light, drying out, or spontaneous biochemical degradation, ”says Claveri. “For example, if their DNA is damaged and cannot be repaired, viruses cease to be infectious. However, among the known viruses, giant viruses are generally very strong and persistent. "
Claveri says viruses can come fromthe very first people who inhabited the Arctic. We could even see viruses of long extinct species of hominids like Neanderthals and Denisovans, which settled in Siberia and were exposed to various viral diseases. In Russia, the remains of Neanderthals aged 30-40 000 years were found. Populations of people lived there, were sick and died for thousands of years.
“The possibility that we can become infectedvirus from a long-vanished Neanderthal, suggests that the idea that the virus can be “eradicated” from the planet is incorrect and gives us a false sense of security. That's why vaccine stocks should be kept just in case. ”
Since 2014, Claveri has been analyzing DNA content inpermafrost in search of a genetic signature of viruses and bacteria that can infect humans. He found many bacteria that could be dangerous to humans. Bacteria have DNA that encodes virulence factors: molecules that produce pathogenic bacteria and viruses that increase their ability to infect a host.
Claveri team also found severalDNA sequences that seem to have been taken from viruses including herpes. But traces of smallpox have not yet been found. For obvious reasons, they did not try to revive any of the pathogens.
It may well be that pathogens, from which people have already lost the habit, can also appear in other places, and not just from ice or permafrost.
In February 2017, NASA scientists said thatfound microbes 10-50,000 years old in crystals in a Mexican mine. These bacteria were located in the Cave of Crystals, part of a mine in Nice in northern Mexico. The cave contains many milky white crystals of mineral selenite, which has been formed over hundreds of thousands of years.
Bacteria were locked in small, liquidpockets of crystals, but as soon as they were pulled out, they were reborn and began to multiply. These microbes are genetically unique and may well be new species, but scientists have not yet published their work.
In the Lechuguilla Cave in New Mexico, 300 metersunderground found even older bacteria. These microbes have not seen the surface for more than 4 million years. The cave never saw sunlight and was isolated for 10,000 years from surface waters.
Despite this, bacteria somehowproved resistant to 18 types of antibiotics, including drugs that were considered the “last barrier” in the fight against infections. In a study published in December 2016, scientists found that bacteria known as Paenibacillus sp. LC231, were resistant to 70% of antibiotics.
Since the bacteria turned out to be completelyisolated in a cave for four million years, they did not come into contact with people or the antibiotics we treat infections. It turns out that their resistance to antibiotics appeared somehow differently.
Scientists believe that bacteria that do notharm to humans, among many others, develop natural resistance to antibiotics. That is, this very antibiotic resistance has existed for millions or even billions of years.
Obviously, such antibiotic resistance could not develop in the clinic during the use of antibiotics.
The reason for this is that many speciesfungi and even other bacteria naturally produce antibiotics to gain a competitive advantage over other microbes. This is how Fleming first discovered penicillin: the bacteria in the Petri dish died after contamination with mold-producing antibiotics.
In caves where there is little food, organisms should beruthless if they want to survive. Bacteria like Paenibacillus might need to develop antibiotic resistance to avoid death from competing organisms.
This explains why bacteria are only resistant tonatural antibiotics that come from bacteria and fungi, and make up about 99.9% of all antibiotics we use. Bacteria have never encountered artificial antibiotics, and therefore have no resistance to them.
“Our work and the work of other peopleevidence that antibiotic resistance is not new, ”said microbiologist Hazel Barton of the University of Akron, Ohio, who led the study. “Our organisms have been isolated from surface species for 4-7 million years, but the resistance they have is genetically identical to that found in surface species. This means that these genes are at least as old and not because people started using antibiotic treatment. ”
Although Paenibacillis is not harmful to humans, in theory it can transfer its antibiotic resistance to other pathogens. But since it is isolated under 400 meters of rocks, this seems unlikely.
Nonetheless, natural antibiotic resistanceto antibiotics is probably so common that many of the bacteria emerging from melting permafrost may already have it. In support of this, in a 2011 study, scientists extracted DNA from bacteria found in permafrost 30,000 years old in the Bering Sea. They found genes encoding resistance to beta-lactam, tetracycline and glycopeptide antibiotics.
Is it worth it to worry about?
It is believed that the risk of pathogenicmicrobes from permafrost are inherently unrecognizable, so you should not worry. Instead, we should focus on the more explicit threats of climate change. For example, as the Earth warms, northern countries may become more susceptible to outbreaks of “southern” diseases like malaria, cholera, and dengue fever, as their pathogens thrive in warmth.
There is still an opinion that risks should not be ignored when we cannot quantify them.
“There is a non-zero probability thatpathogenic microbes can revive and infect us, ”says Claveri. “How likely this is is still unknown, but likely. Perhaps these bacteria can be cured with antibiotics, resistant bacteria, and the virus. If the pathogen has not been in contact with people for a long time, the immune system will not be ready. So there is a danger. ”