Throughout the history of our planet, humans have coexisted with bacteria and viruses. We looked for ways to resist bubonic plague and smallpox, and in response they looked for ways to infect us. We have been using antibiotics for almost a century, ever since Alexander Fleming discovered penicillin. In response, the bacteria have developed antibiotic resistance. There is no end to the battle. We spend so much time with pathogens that we take turns stumping each other. However, what happens if we suddenly encounter deadly bacteria and viruses that have not been encountered in thousands of years or have never been seen?
Perhaps we will soon find out. Climate change results in the thawing of permafrost soils that have been frozen for thousands of years, and as the soil thaws, ancient viruses and bacteria emerge that come to life and return to life.
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 contracting anthrax.
It has been suggested that more than 75 years ago, a deer infected with anthrax died and its frozen skeleton was trapped under a layer of frozen soil, under permafrost. He remained there until the summer of 2016, when the permafrost thawed due to intense heat. Thus, she released the corpse of a deer and an anthrax infection into the nearest waters and soil, and then into the food supply. People are under threat.
The scary thing is that this may not be an isolated incident.
The earth is warming up and thawing more permafrost. Under normal conditions, the surface layers of permafrost, about 50 centimeters deep, thaw every summer. But global warming is gradually exposing old permafrost layers.
Promotional video:
Frozen perennial soil is an ideal place for bacteria to stay alive for long periods of time, perhaps millions of years. This means that melting ice could potentially open a Pandora's box of diseases.
Temperatures in the Arctic Circle are rising rapidly, about three times faster than the rest of the world. Other infectious agents can also come out.
“The permafrost is an excellent keeper of germs and viruses because it is cold, dark and lacking oxygen,” says evolutionary biologist Jean-Michel Claverie of the University of Aix-Marseille in France. "Pathogenic viruses that can infect animals and plants may have been stored in old permafrost layers of soil, including those that caused global epidemics in the past."
In the early 20th century alone, more than a million reindeer died from anthrax. In the north, it is not easy to dig deep graves, so most of these carcasses were buried close to the surface, in 7,000 scattered burials in northern Russia.
What else could be hidden under the frozen soil?
People and animals have been buried in the permafrost for hundreds of years, so it is possible that other infectious agents may also come out. For example, scientists have found fragments of the RNA of the Spanish flu virus in corpses massively buried in the Alaskan tundra. Smallpox and bubonic plague are also buried in Siberia. In a 2011 study, Boris Revich and Marina Podolnaya wrote: "As a result of the thawing of permafrost, vectors of deadly infections of the 18th and 19th centuries may return, especially near cemeteries where victims of these infections were buried."
In the 1890s, a serious smallpox epidemic took place in Siberia. One city lost up to 40% of its population. The bodies were buried under the upper layer of permafrost on the banks of the Kolyma River. After 120 years, floods of the Kolyma River began to erode the banks, and the melting of the permafrost accelerated this erosion process.
In a project that began in the 1990s, scientists from the State Research Center for Virology and Biotechnology in Novosibirsk studied the remains of Stone Age humans found in southern Siberia, in the Altai region. 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 have found bodies with ulcers characteristic of smallpox marks. Although they didn't find the smallpox virus itself, they found DNA fragments.
Of course, this is not the first time that bacteria frozen in ice have come to life again.
In a 2005 study, NASA scientists successfully revived bacteria trapped in a frozen pond in Alaska for 32,000 years. A microbe called Carnobacterium pleistocenum has been frozen since the Pleistocene, when woolly mammoths were still roaming the Earth. As soon as the ice melted, they began to swim again as if nothing had happened.
Two years later, scientists were able to revive an 8 million-year-old bacterium that had been sleeping in ice beneath a glacier in the Beacon and Mullins valleys in Antarctica. In the same study, bacteria were recovered from ice more than 100,000 years old.
However, not all bacteria can come back to life after being frozen in permafrost. The anthrax bacteria can do this because they form extremely hardy spores that can live frozen for a very long time.
Other bacteria that can form spores and thus survive in permafrost include tetanus and Clostridium botulinum, which is responsible for botulism, a rare disease that can cause paralysis and death. Some fungi 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 by Claveri revived two viruses trapped in Siberia's permafrost 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.
Viruses became infectious immediately after the revival. Fortunately for us, these particular viruses only infect single-celled amoebas. However, research suggests that other viruses that can infect humans may also be reborn.
Moreover, global warming does not have to melt permafrost to pose a threat. As the Arctic sea ice melts, the northern coast of Siberia becomes easier to reach by sea. Obviously, its industrial development is becoming more profitable, including the extraction of gold and minerals, the drilling of oil wells, and the extraction of natural gas.
“At the moment, these areas are empty, and no one is touching the deep layers of permafrost,” Claverie says. “But these ancient layers can be obtained during excavation and drilling operations. If viable virions still live there, it will be a disaster."
Giant viruses can be the most likely culprits in a viral outbreak.
“Most viruses are rapidly inactivated outside of host cells due to light, drying out, or spontaneous biochemical degradation,” Claverie says. “For example, if their DNA is damaged and cannot be repaired, viruses cease to be infectious. However, among the known viruses, giant viruses are usually very tough and persistent."
Claverie says viruses from the earliest humans to inhabit the Arctic could emerge. We might even see viruses of long-extinct hominid species like the Neanderthals and Denisovans, who settled in Siberia and were exposed to various viral diseases. In Russia, the remains of Neanderthals 30-40,000 years old were found. Human populations have lived there, have been sick and died for thousands of years.
“The possibility that we could catch the virus from a long-extinct Neanderthal suggests that the idea that the virus can be“eradicated”from the planet is wrong and gives us a false sense of security. This is why vaccine supplies should be kept just in case.”
Since 2014, Claverie has been analyzing DNA content in permafrost in search of the genetic signature of viruses and bacteria that can infect humans. He found many bacteria that can be dangerous to humans. Bacteria have DNA that codes for virulence factors: molecules that pathogenic bacteria and viruses produce that increase their ability to infect a host.
Claverie's team also discovered several DNA sequences that appear to have come from viruses, including herpes. But no traces of smallpox have yet been found. For obvious reasons, they did not attempt to revive any of the pathogens.
It may well be that pathogens, from which people have already become unaccustomed, can manifest themselves in other places, and not only from ice or permafrost.
In February 2017, NASA scientists said they had found 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 Naiza in northern Mexico. The cave contains many milky white crystals of the mineral selenite, which has formed over hundreds of thousands of years.
The bacteria were trapped in small, liquid pockets of crystals, but as soon as they were taken out, they revived and began to multiply. These microbes are genetically unique and may well be new species, but scientists have not yet published their work.
Even older bacteria were found in Lechugilla Cave in New Mexico, 300 meters underground. These microbes have not seen the surface for over 4 million years. The cave has never seen sunlight and has been isolated for 10,000 years from surface waters.
Despite this, the bacteria somehow proved to be resistant to 18 types of antibiotics, including drugs that were considered the "last hurdle" in the fight against infections. In a study published in December 2016, scientists found that the bacteria known as Paenibacillus sp. LC231 were resistant to 70% of antibiotics.
Since the bacteria were completely isolated in the cave for four million years, they did not come into contact with humans or the antibiotics we use to treat infections. It turns out that their resistance to antibiotics appeared somehow differently.
Scientists believe that bacteria that do not harm humans, among many others, develop natural antibiotic resistance. 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 types of fungi and even other bacteria naturally produce antibiotics in order to gain a competitive advantage over other microbes. This is how Fleming first discovered penicillin: the bacteria in the petri dish died after being contaminated with antibiotic-producing molds.
In caves where food is scarce, organisms must be ruthless if they want to survive. Bacteria like Paenibacillus may have had to develop antibiotic resistance to avoid death from competing organisms.
This explains why bacteria are only resistant to natural antibiotics that come from bacteria and fungi, and make up about 99.9% of all antibiotics we use. Bacteria have never encountered artificial antibiotics, so they have no resistance to them.
“Our work and that of others show that antibiotic resistance is nothing 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 resilience they have is genetically identical to that found in surface species. This means that these genes are at least as old and did not appear because people started using antibiotic treatment."
Although Paenibacillis is not harmful to humans, in theory it can transmit its antibiotic resistance to other pathogens. But since it is isolated under 400 meters of rock, this seems unlikely.
Nonetheless, natural antibiotic resistance to antibiotics is probably so widespread that many of the bacteria emerging from the melting permafrost may already have it. In support of this, in a 2011 study, scientists extracted DNA from bacteria found in 30,000-year-old permafrost in the Bering Sea. They found genes encoding resistance to beta-lactam, tetracycline, and glycopeptide antibiotics.
Is it worth worrying?
It is believed that the risk of the appearance of pathogenic microbes from the permafrost is inherently unknowable, so there is no need to worry. Instead, we must focus on the more explicit threats from climate change. For example, as the earth warms, northern countries may become more susceptible to outbreaks of "southern" diseases like malaria, cholera, and dengue, as their pathogens thrive in the warmth.
There is also an opinion that we should not ignore the risks when we cannot quantify them.
“There is a non-zero chance that pathogenic microbes can re-emerge and infect us,” Claverie says. “How likely this is is not yet known, but it is likely. Perhaps these bacteria can be cured with antibiotics, resistant bacteria, a virus. If the pathogen has not been in contact with humans for a long time, the immune system will not be ready. So there is danger."
ILYA KHEL