There are different diseases in the world. But none of them caused such horror and fear as the plague. This disease has known no mercy since ancient times. She claimed millions of lives, regardless of gender, age and well-being of people. Today, the disease no longer brings a huge amount of death and grief. Thanks to the miracles of modern medicine, the plague has been turned into a less dangerous disease. However, it was not possible to completely eradicate the disease. The plague bacillus (Yersinia pestis), which causes disease, continues to exist in this world and infect people.
Pathogen Ancestor
Several years ago, microbiologists began to conduct research to study the evolution of pathogens. Plague wand was also studied. Among the existing microorganisms, a bacterium genetically similar to it, Yersinia pseudotuberculosis, was found. This iscausative agent of pseudotuberculosis.
Research allowed scientists to draw one conclusion. When life began to emerge on the planet, there were no plague sticks yet. Approximately 15-20 thousand years ago there was a causative agent of pseudotuberculosis. It was a consumer of dead organics, multiplied in animal excrement, around corpses buried in the ground. Some factors provoked further its evolution. Part of the pathogens of pseudotuberculosis transformed into a plague bacillus.
How evolution happened
In those places where the primary foci of plague arose, the causative agent of pseudotuberculosis lived in the burrows of marmots (tarbagans). Its evolution, that is, the appearance of the plague wand, was facilitated by certain factors:
- The presence of fleas on animals. When groundhogs hibernated, insects accumulated on their snouts. This was the most favorable place for them to live. In winter, the temperature in the hole was always negative. Only the mouth and nose of the animals were a source of warm air.
- The presence of bleeding wounds on the mucous membrane of the oral cavity of marmots. Fleas living on the muzzles bit the animals throughout the winter. Bleeding occurred at the bite sites. They did not stop because the animals were sleeping and their body temperature was low. Active groundhogs would stop bleeding quickly.
- Presence of Yersinia pseudotuberculosis on the paws of animals. Tarbagans before hibernation buried the entrances to the holes with their own droppings. Because of this, pathogens of pseudotuberculosis accumulated on their paws.
Whenthe animals fell into hibernation, they covered their muzzles with their paws. The causative agents of pseudotuberculosis got into the wounds formed due to flea bites. In the circulatory system of active animals, this bacterium could not survive. The macrophages would kill her instantly. But in the sleeping marmots for Yersinia pseudotuberculosis there were no threats. The blood was cooled to favorable temperatures, and the immune system was "turned off". Of course, there were rises in temperature, but rare and short. They created ideal conditions for the natural selection of pathogen forms. All these processes eventually led to the birth of the plague wand.
Disease epidemics in the past
Modern scientists cannot say whether the plague has always pursued people. According to the surviving information, only three major epidemics are known. The first of these, the so-called Plague of Justinian, began around the 540s in Egypt. For several decades, the plague wand devastated almost all the states of the Mediterranean.
The second epidemic, called the "Black Death", was recorded in the middle of the XIV century. The plague wand has spread from a natural focus in the Gobi Desert due to dramatic climate change. The causative agent later penetrated into Asia, Europe, North Africa. The island of Greenland was also affected by the disease. The second epidemic greatly affected the population. The plague wand claimed an estimated 60 million lives.
The third plague began at the end of the 19th century. An outbreak of the disease was recorded in China. 174 thousand people died in this country in 6 monthsHuman. The next outbreak occurred in India. In the period from 1896 to 1918, 12.5 million people died from the causative agent of a dangerous disease.
Plague and modernity
Currently, scientists, analyzing the consequences of epidemics and studying important historical sources, call the plague "the queen of diseases." At the same time, it no longer causes such fear and horror, because no other major outbreaks were recorded in the world that claimed millions of lives.
On the manifestations of the plague in the modern period, statistics are kept. The World He alth Organization notes that 3,248 people fell ill with plague between 2010 and 2015. The lethal outcome was in 584 cases. This means that 82% of people recovered.
Reasons for weakening the "grip" of the pathogen
The Plague Wand has become less dangerous for several reasons. First, people began to observe the rules of hygiene, cleanliness. For example, we can compare the modern period with the Middle Ages. Several centuries ago in Western Europe, people threw all their food waste and feces right on the streets. Due to environmental pollution, the townspeople suffered from various diseases, died from the plague.
Secondly, modern people live far from natural foci of the disease. Only hunters and tourists most often encounter infected rodents and fleas.
Thirdly, today medicine knows effective ways to treat and prevent a dangerous disease. Specialists have created vaccines, identified drugs that are capable ofkill the plague wand.
And now about the pathogen
If we talk about the structure of the plague bacillus, then Yersinia pestis is a gram-negative small bacterium. It is characterized by pronounced polymorphism. This is confirmed by the occurring forms - granular, filiform, flask-shaped, oblong, etc.
Yersinia pestis is a zoonotic bacterium belonging to the Enterobacteriaceae family. The generic name Yersinia was given to this microorganism in honor of the French bacteriologist Alexandre Yersin. It was this specialist who, in 1894, during the study of biological materials of people who died from a dangerous disease, was able to identify the pathogen.
A microorganism capable of causing epidemics with a high lethality rate has always been of interest to microbiologists once discovered. Since the discovery of Yersinia pestis, specialists have studied the structure of the bacterium (plague bacillus) and its features. The result of some studies conducted by domestic scientists was the compilation in 1985 of the classification of the pathogen isolated on the territory of the USSR and Mongolia.
| Subspecies of the plague wand | Circulation area |
| Pestis (Main) | Natural hotspots of Asia, America and Africa |
| Altaica (Altaic) | Gorny Altai |
| Caucasica (Caucasian) | Transcaucasian Highlands, Mountainous Dagestan |
| Hissarica (Hissar) | Hissar Range |
| Ulegeica (Ulege) | Northeastern Mongolia, Gobi Desert |
Wand Penetration Methods
The causative agent of plague lives in the body of small mammals. In the circulatory system, the bacillus multiplies. A flea during the bites of infected animals becomes a carrier of infection. In the body of an insect, the bacterium settles in the goiter, begins to multiply intensively. Due to the increase in the number of sticks, the goiter becomes clogged. The flea begins to experience severe hunger. To satisfy him, she jumps from one owner to another, while spreading the infection between animals.
The stick enters the human body in several ways:
- when bitten by an infected flea;
- during unprotected contact with contaminated materials and infected body fluids;
- by inhalation of infected small particles or fine droplets (airborne droplets).
Disease forms and symptoms
Depending on how the plague bacillus penetrates the body, 3 forms of the disease are distinguished. The first one is bubonic. With such a plague, the pathogen enters the human lymphatic system after a flea bite. Due to the disease, the lymph nodes become inflamed, becoming the so-called buboes. In the later stages of the plague, they turn into festering wounds.
The second form of the disease is septic. With it, the pathogen enters directly into the bloodstreamsystem. Buboes are not formed. The septic form occurs when the plague bacillus enters the human body in two ways - after the bite of an infected flea, and also after contact with infected materials (the pathogen enters through skin lesions).
The third form is pulmonary. It is transmitted from infected patients by airborne droplets. The pulmonary form of plague is considered the most dangerous. Without treatment, the result of the progression of the disease in most cases is death.
Cure the plague
For a long time, humanity did not know about the methods of penetration of the plague bacillus, did not know how to stop a deadly disease. Doctors came up with various bizarre ways that did not lead to a cure. For example, in the Middle Ages, healers prepared incomprehensible potions from plants, crushed snakes, advised people to quickly and permanently flee from the infected area.
Today, plague is treated with antibiotics from the aminoglycoside group (streptomycin, amikacin, gentamicin), tetracyclines, rifampicin, chloramphenicol. Fatal outcomes occur in cases where the disease proceeds in a fulminant form, and specialists fail to identify the pathogenic bacterium in a timely manner.
The plague bacillus, despite the achievements of modern medicine, still refers to insidious pathogens. The foci of the disease in nature occupy about 7% of the land. They are located on desert and steppe plains, in highlands. People who have been in the natural foci of the plague should pay attention to their he alth. When the pathogen enters the body, the incubation period lasts from several hours to 9 days. Then the first symptoms appear - the body temperature suddenly rises to 39 degrees and above, convulsions, chills, severe headache and muscle pain occur, breathing becomes difficult. These symptoms require immediate medical attention.
