Bacterium "plague bacillus": description, features and treatment of infection
There are various diseases in the world. But none of them caused such horror and fear as the plague. This disease since ancient times did not know mercy. It took millions of lives, regardless of sex, age and people's well-being. Today the disease does not bring a huge number of deaths and grief. Thanks to the wonders of modern medicine, the plague was turned into a less dangerous disease. However, it was not possible to completely eradicate the disease. The plague wand( Yersinia pestis), causing the disease, continues to exist in this world and hit people.
Ancestor of the causative agent
Several years ago, microbiologists began to conduct research to study the evolution of pathogens. The rod of the plague was also studied. Among the existing microorganisms there was a genetically similar bacterium - Yersinia pseudotuberculosis. It is the causative agent of pseudotuberculosis.
The conducted researches allowed scientists to draw one conclusion. When life started on the planet, the plague rods were not there yet. Approximately 15-20 thousand years ago there was a causative agent of pseudotuberculosis. He was a consumer of dead organics, multiplying in the feces of animals, around corpses buried in the ground. Some factors provoked its evolution in the future. Part of the pathogens of pseudotuberculosis was transformed into a plague rod.
How the evolution of
occurred In those places where the primary foci of plague arose, the causative agent of pseudotuberculosis lived in burrows of marmots( tarbagans).Its evolution, that is, the emergence of the plague rods, contributed to certain factors:
- The presence of animal fleas. When marmots fell into a hibernation, insects accumulated on their muzzles. This was the most favorable place for their dwelling. In winter there was always a negative temperature in the hole. Only the mouth and nose of the animals were a source of warm air.
- Presence of bleeding wounds on mucosa of oral cavity. Migratory fleas bitten animals throughout the winter. Bleeding occurred in places where there were bouts. They did not stop, because the animals were asleep, and their body temperature was low. In active marmots, bleeding would quickly cease.
- Presence of Yersinia pseudotuberculosis on the legs of animals. Tarbagans before hibernation buried the entrances to the burrows with their own litter. Because of this, pseudotuberculosis pathogens accumulated on their paws.
When the animals fell asleep, they covered their muzzles with their paws. In the wounds, formed due to flea bites, the causative agents of pseudotuberculosis were included. In the circulatory system of active animals, this bacterium could not survive. She would have been killed instantly by macrophages. But in the sleeping marmots for Yersinia pseudotuberculosis there were no threats. The blood was cooled to a favorable temperature, and the immunity was "turned off".Of course, the temperature rises occurred, but rare and short. They created ideal conditions for the natural selection of the forms of the pathogen. All these processes eventually led to the birth of a plague rods.
Epidemics of the disease in the past
Modern scientists can not say whether the plague always persecuted people. According to the surviving information, only three major epidemics are known. The first of them - the so-called Justinian plague - 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 of the plague spread from a natural hearth in the Gobi desert due to a sharp climate change. The causative agent later penetrated into Asia, Europe, and North Africa. The affected island was Greenland. The second epidemic had a very strong impact on the population. The wand of plague took away about 60 million lives.
The third plague epidemic began in the late 19th century. The outbreak was recorded in China. For 6 months, 174 thousand people died in this country. The next outbreak occurred in India. Between 1896 and 1918, 12.5 million people died from the pathogen of a dangerous disease.
Plague and modernity
Currently, scientists, analyzing the consequences of epidemics and studying important historical sources, call the plague "queen of diseases".At the same time, it no longer causes such fear and horror, because there were no more large flashes in the world that took millions of lives.
The manifestations of the plague in the modern period are statistics. The World Health Organization notes that between 2010 and 2015 the plague plagued 3,248 people. The lethal outcome was in 584 cases. This means that 82% of people have recovered.
The reasons for the weakening of the "grip" of the causative agent
Plague wand has become less dangerous for several reasons. First, people began to observe the rules of hygiene, cleanliness. For example, you can compare the modern period with the Middle Ages. Several centuries ago in Western Europe, people threw away all food waste and feces directly into the streets. Because of the pollution of the environment, the townspeople suffered from various diseases, died of plague.
Secondly, modern people live far from the natural foci of the disease. With infected rodents and fleas, only hunters and tourists most often come across.
Third, to date, medicine knows effective ways to treat and prevent a dangerous disease. Specialists created vaccines, identified drugs that are capable of killing a stick of the plague.
And now about the causative agent
If we talk about the structure of the plaque, then Yersinia pestis is a gram-negative small bacterium. It has a pronounced polymorphism. Confirm this encountered forms - granular, filamentous, bulbous, elongated, etc.
Yersinia pestis is a zoonotic bacterium belonging to the family Enterobacteriaceae. To this microorganism the generic name Yersinia was given in honor of the French bacteriologist Alexander Jersen. It was this specialist 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 mortality rate, after detection, has always been of interest to microbiologists. Specialists since the discovery of Yersinia pestis have studied the structure of the bacterium( plague bacillus), its features. The result of some studies conducted by domestic scientists was the compilation in 1985 of a classification of the pathogen isolated in the territory of the USSR and Mongolia.
| Circulation Districts( main) | Natural foci of Asia, America and Africa | |
| Altaica( Altay) | Mountainous Altai | |
| CaucasicaCaucasus) | The Transcaucasian Highlands, Mountainous Dagestan | |
| Hissarica( Hissarian) | Hissar Range | |
| Ulegeica( uldejsky) | Northeast Mongolia, Gobi Desert |
Ways of penetration of the rod
The causative agent of the plague lives in therganizme small mammals. In the circulatory system, the rod multiplies. Flea during the bites of infected animals becomes a carrier of infection. In the insect organism the bacterium settles in the goiter, begins to multiply intensively. Because of the increase in the number of rods, goiter is blocked. The flea begins to experience severe hunger. For its quenching, it jumps from one master to another, while spreading the infection between the animals.
In the human body, the rod comes in several ways:
- when bitten by an infected flea;
- during unprotected contact with contaminated materials and infected biological fluids;
- by inhalation of infected small particles or fine droplets( by airborne droplets).
Forms of the disease and symptoms
Depending on the methods of penetration of the plaque, 3 forms of the disease are recognized. The first of these is bubonic. With such a plague, the pathogen enters the human lymphatic system after a flea bite. Because of the disease, the lymph nodes become inflamed, become so-called buboes. In the later stages of the plague, they become purulent wounds.
The second form of the disease is septic. With her, the pathogen gets directly into the circulatory system. Bubbons are not formed. The septic form occurs when there are two ways of penetrating the plague rod into the human body - after the bite of the infected flea, as well as after contact with the infected materials( getting the pathogen through skin lesions).
The third form is pulmonary. It is transmitted from infected patients by airborne droplets. The pulmonary form of the plague is considered the most dangerous. Without treatment, the outcome of disease progression in most cases is a lethal outcome.
Treatment of plague
For a long time, mankind did not know about the ways of penetration of the plague rod, did not guess how to stop the deadly disease. The healers invented 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 flee quickly and permanently from the contaminated area.
Today, the plague is treated with antibiotics from the group of aminoglycosides( streptomycin, amikacin, gentamycin), tetracyclines, rifampicin, levomycetin. Lethal outcomes occur in those cases when the disease occurs in a lightning-fast form, and specialists fail to detect a pathogenic bacterium in time.
Plague wand, despite the achievements of modern medicine, still refers to insidious pathogens. Foci of disease in nature occupy about 7% of the land area. They are located in the desert and steppe plains, in the highlands. People who have visited natural foci of the plague should pay attention to their health. When the pathogen enters the body, the incubation period lasts from several hours to 9 days. Then there are the first symptoms - suddenly the body temperature rises to 39 degrees and above, there are convulsions, chills, severe head and muscle pain, difficulty breathing. With such symptoms, you need to see a doctor immediately.