Bacteria: the silent conductors of the modern world

However, despite their technological advantage, which included the latest weapons — muskets — the Spaniards were vastly outnumbered by the large armies of indigenous people, making direct confrontation with them extremely risky. Therefore, the Spaniards decided first to build alliances with the local tribes, keeping their conquest intentions for the future.

When the chief of one of the tribes invited the Spanish conquistadors to a reception, one of the guests sneezed, which caused amused laughter among the locals. But no one suspected that this simple sneeze would lead to a mass tragedy: a week later, the chief’s daughter and her servants fell ill with a high fever and severe headache. Another week passed, and the disease spread, affecting 50 people, and within a month, most of the tribe was covered in a mysterious rash, and all members of that tribe soon died of asphyxiation. Seeing the mass deaths, the indigenous people decided that the gods were angry due to an insufficient number of sacrifices, while the Spaniards saw it as a heavenly sign, convinced that God was on their side and was destroying their enemies.

After the sharp decline in the indigenous population, the conquistadors, armed with muskets and other firearms, quickly seized the desired lands. Weakened by disease, the indigenous people could no longer offer serious resistance. The Spaniards quickly established control over the territories and, using the labor of the remaining indigenous people, began extracting vast quantities of gold, which they sent to Spain to strengthen their positions in the colonies.

So what was this invisible weapon that managed to kill off most of the indigenous population?

The invisible weapon, which even before the discovery of America had struck Eurasia and claimed hundreds of millions of lives, also impacting the African continent, was tiny creatures known as bacteria. In 16th-century America, they triggered a smallpox epidemic; in 14th-century Eurasia, they ignited a plague epidemic. Even Cortés himself died from a bacterial disease affecting lung tissue, so perhaps it was not bacteria after all?

Bacteria are single-celled, living organisms — unlike viruses. They are the oldest inhabitants of our planet, which scientists believe may have come to Earth from space. Bacterial cells, composed of nuclei, are so tiny that they can only be seen under very high magnification, and these small creatures live everywhere: in soil, water, on the surfaces of plants and animals, and even inside the human body. The diversity of their species is astounding — there are bacteria in the form of rods, spheres, and spirals, and each type serves a unique function.

Some bacteria live in the human gut and help digest food. You’ve definitely encountered them in yogurt, cheese, and other fermented foods. These beneficial bacteria help break down complex substances, making human digestion more efficient, and at the same time, they strengthen the immune system. Beneficial bacteria, like tiny workers, tirelessly labor for the good of human health.

But among bacteria, there are very dangerous types that cause terrible epidemics and, slowly but surely, attempt to destroy humanity. Their tiny size and rapid reproduction rate make them truly formidable opponents. How do they enter our world?

Sometimes it all starts with a simple touch, and sometimes bacteria are transmitted to humans through contaminated food or water. When the Spaniards brought smallpox to the New World, they opened the gates to a disease against which the native population had no immunity. The bacteria that caused smallpox were completely new to the indigenous people — their bodies were not prepared to fight this infection. As a result, this invisible weapon became a weapon of mass destruction, claiming millions of lives.

A similar story happened with the so-called “curse of the pharaohs.” When archaeologists began opening ancient Egyptian tombs in the early 20th century, they inhaled air that had preserved bacteria and fungi isolated for thousands of years. Modern archaeologists had no immunity to these microorganisms, leading to serious infections and even death.

However, the spread of this dreadful disease was also fueled by medieval beliefs: black cats, considered at the time to be messengers of Satan, were killed en masse across Europe. This religious fanaticism had predictable consequences — there was no one left to hunt the rats, which multiplied at an unprecedented rate. Rats, becoming the main carriers of the plague, rapidly filled towns and villages, spreading the infection and turning Europe into a vortex of death and destruction.

Bubonic plague struck suddenly: infected people experienced a rapid increase in temperature, and large black swellings, or “buboes,” appeared on their necks, underarms, and groin, causing unbearable pain. The inflamed lymph nodes, filled with pus, caused excruciating suffering — as the lymphatic system fought the infection but could not overcome it.

The plague bacteria affected the lungs, causing uncontrollable coughing, and the disease often ended in suffocation: the lungs became inflamed and filled with fluid, depriving people of the ability to breathe.

Plague victims died quickly, sometimes within 2–4 days of the first symptoms. The bodies of the deceased filled the streets, as local authorities could not keep up with burial demands. A stench hung over the cities, and the fear of the inevitable drove people to desperate measures — they were forced to abandon their families and flee infected areas.

By various estimates, the plague had killed up to a third of Europe’s population by the end of the 14th century, turning cities into ghost towns, paralyzing economic and cultural life, and altering the structure of European society. The sharp decline in the workforce led to wage increases for survivors and weakened feudal systems. The mass deaths also triggered a surge in mysticism and religious movements, heightening the panic.

Yet, amid all the horrors that the plague bacteria brought, the human body developed defense mechanisms — antibodies, a sort of biological “shield and sword” against pathogens.

Each microbe has its own “mark,” similar to a fingerprint, and each antibody has a key that matches that specific mark. For example, if a cold virus enters the body, antibodies with the key for the cold virus will immediately know what to do. They “fight off” the virus, and the body recovers more quickly.

Antibodies fight microbes here and now, but they also “remember” them to defeat familiar viruses much faster in the future. However, bacteria themselves become smarter over time: they adapt and constantly search for ways to weaken the body’s defenses.

19th century, Paris. A young man named Arthur fell in love with a beautiful woman named Émilie. She was the girl he had dreamed of, with bright blue eyes, golden hair, and a charm that made him lose his senses. Arthur was enchanted, and their love felt eternal. However, Émilie began to cough frequently. At first, the cough didn’t bother her much, but over time it became more persistent and distressing. Despite this, Émilie seemed more beautiful each day, though Arthur sensed that a sinister enemy lay behind this beauty. Émilie was losing her appetite, her figure growing increasingly fragile. Each time she coughed, Arthur’s chest tightened with pain. He tried to cheer her up, but he was powerless against the illness; her health deteriorated rapidly.

Arthur watched as Émilie faded away, her smile increasingly hidden behind a mask of fear and exhaustion. She continued to dream of the future, and though her eyes still shone with hope, Arthur knew her strength was waning. Each breath was a painful ordeal, each cough was accompanied by blood.

One fine morning, Arthur awoke to find Émilie smiling widely. She felt much better and looked beautiful — her cheekbones were prominent, and she had a flush on her cheeks. Arthur rejoiced, thinking God had heard their prayers, but three days later, Émilie died of tuberculosis.

Tuberculosis, also known as consumption, became one of the deadliest foes of the late 19th and early 20th centuries, wiping out a quarter of the world’s population. Yet, at the same time, tuberculosis became a kind of “trend,” a fashionable illness, as those infected acquired a morbid allure. Thinness, bright cheeks, and pronounced cheekbones led nobles to think tuberculosis was an illness of the elite, surrounded by romance rather than fear and ugliness, like the bubonic plague.

For instance, Erich Maria Remarque often referenced tuberculosis in his works. In his novel Three Comrades, he made this disease the main enemy that took the life of the protagonist’s wife, emphasizing the harsh reality of that era.

All the suffering caused by tuberculosis and other dangerous diseases motivated scientists to start looking for ways to fight these treacherous enemies. This is how Plan B for any illness — antibiotics — entered our lives.

How do antibiotics work? They attack bacteria and destroy them from the inside. In this way, they resemble special agents on a mission to sabotage and destabilize. Antibiotics break down the walls of bacterial cells, preventing them from growing and reproducing.

However, this 20th-century medical miracle needs to be used carefully: if taken uncontrollably, beneficial bacteria can be destroyed, opening the door for more malicious viruses.

Antibiotics truly became an essential weapon against bacteria, and along with them came other ways to protect the body — vaccinations. When a very weak or even dead part of a bacteria or virus is introduced into a person’s body, the body “remembers” the enemy and creates a “special army” of antibodies.

Yet, despite the fact that the discovery of antibiotics and vaccines saved millions of lives, the world experienced another shock that set medical progress back by centuries. World War II began.

The war destroyed cities and lives, while also redirecting scientific research. Instead of focusing solely on developing new medicines and saving people, scientists began working on new types of weaponry, including bacteriological weapons.

But such a tactic was not entirely new. In Ancient Rome, during sieges, attackers would throw bodies of plague victims over the walls to spread disease among the besieged.

In 1346, the Genoese city of Kaffa (modern-day Feodosia) was under siege by the forces of Golden Horde Khan Janibek. An outbreak of plague hit the Khan’s army, killing hundreds of soldiers daily. The city’s defenses were holding, and it seemed that the besiegers would soon be unable to continue their assault.

But Janibek found a brutal and cunning way to break the siege: he ordered the bodies of plague-stricken soldiers to be catapulted into the city. This barbaric tactic worked effectively — the plague entered the city walls, and an epidemic spread through Kaffa. The residents began dying en masse, and the city surrendered. However, the disaster didn’t end there. Trade routes carried the plague further: it left Feodosia and began its deadly harvest, spreading throughout Europe.

Some researchers believe that after the discovery of America, the indigenous population, originally numbering 20 million, was cut in half; the conquistadors used disease as a weapon, albeit unintentionally at first.

In 1763, at Fort Pitt (present-day Pittsburgh), there was a recorded instance of intentional infection — the besieged British left blankets and clothing from smallpox victims near the Native American camp, which led to an epidemic and forced the attackers to retreat. The response from the Native Americans was not long in coming: there is a theory that syphilis was brought to Europe from America. This hypothesis, called the “Columbian hypothesis,” suggests that syphilis was introduced to Europe in the late 15th century by Christopher Columbus’s expedition after returning from the New World.

One of the most infamous cases of using bacterial weapons is associated with “Unit 731.” This secret military group, which included Japanese scientists, conducted brutal experiments, infecting people with plague, cholera, and other deadly diseases. The military even used infected bombs, which they dropped on Chinese villages, causing mass epidemics.

German scientists also experimented with biological weapons, though their programs did not reach the same scale. They developed plans to use diseases such as botulism and anthrax to infect animals and devastate enemy countries’ agriculture.

The British and Americans also took part in the development. They created laboratories where methods were developed for using anthrax and other bacteria.

Fortunately, plans for the mass use of biological weapons in World War II were never implemented on battlefields, but the mere possibility that bacteria could be turned into a tool of mass destruction forever changed the approach to studying viruses.

As the horrors of biological weapons became clear, scientists began to realize that the potential of bacteria should be used not for destruction, but for creation.

Researchers are working on ways for microorganisms to clean oceans and rivers, preventing ecological disasters. Bacteria can break down oil and toxic waste, purifying polluted waters and soils. The world’s oceans have accumulated vast amounts of plastic, which takes hundreds of years to decompose, but there are types of bacteria capable of consuming plastic and turning it into safe substances. This process is called “bioremediation.”

Scientists are also exploring the possibility of using bacteria to treat various diseases. In the future, bacteria may be able to find cancer cells in the body and destroy them without harming healthy tissues. This approach could lead to new types of treatments that are more effective and safer than current methods.

In addition to treating cancer, bacteria are already used to create vaccines, antibiotics, and probiotics that support a healthy balance of microflora in the body. Bacteria are also used in gene therapy to deliver drugs to targeted cells.

Scientists are also investigating how bacteria could help in the colonization of other planets. For example, they might be used to create fertile soil on Mars or to recycle waste in closed systems such as space stations.

Every day, scientists worldwide are developing new drugs, but at the same time, other researchers continue to work on bacteriological weapons capable of wiping entire cities off the face of the Earth.

We don’t know what lies hidden beneath ancient glaciers. The glaciers are melting, and each year they release ancient bacteria, which are millions of years old. These organisms were once capable of causing diseases that had no cure, and who knows what they might be now? Our bodies have no immunity to them, and if the diseases of past centuries return to the world, the consequences could be catastrophic.

The most alarming aspect of this situation is that antibiotics, our main weapon against bacteria, are becoming ineffective. This is one of the most significant medical threats of recent decades. More and more bacteria are becoming resistant to antibiotics, and scientists predict that by 2050, more than 39 million people may die from infections caused by antibiotic-resistant microorganisms, which will become unresponsive to medication. Currently, in Europe alone, 35,000 people die each year from diseases caused by resistant pathogens.

The crisis is exacerbated by the lack of new antibiotics. Since 2017, only 12 new drugs have been approved, which is not enough to combat the growing threat. The question of the future of our healthcare system is becoming increasingly urgent, as humanity may soon find itself defenseless against bacteria that are impervious to modern medicines. With the increase in antibiotic resistance, we may witness the rise of “superbugs” that cannot be treated with traditional methods.

Humanity stands on the brink of a new era, where the microscopic world may become either a friendly ally or a most treacherous foe. Bacteria are everywhere — in the soil, in the air, in our bodies — and they are not always on our side. And if we do not prepare for this new threat, we may find ourselves utterly defenseless in the face of a looming pandemic.

The question we are left with is both frightening and intriguing: what fate awaits humanity in a world where bacteria grow ever stronger, and our understanding of their power grows ever deeper?