The causative agent of bubonic plague. What causes the plague. Plague as a biological weapon

The extremely severe disease plague or “black death” has now been almost completely eradicated. If rare cases of infection occur, then with timely treatment death does not exceed 10%. For comparison: during the first pandemics, which ruled for almost centuries, the mortality rate from the bubonic form of plague was 95%, and from the pneumonic form it was close to 99%.

Plague symptoms and routes of infection

Plague is hard infection related to quarantine diseases. The causative agent of the plague was discovered in 1894 independently by the French scientist A. Yersin and the Japanese scientist S. Kitasato.

The causative agent is a bacterium that does not form spores, has a capsule, and produces toxins both during life and after destruction. It is stable at low temperatures, can survive in rodent burrows for several months, and in fleas and ticks for more than a year. Boiling and disinfectants easily kill it.

Look what the causative agents of the plague look like in the photo:

Microbiologists believe that the causative agent of the plague appeared approximately 1500-2000 years ago as a result of a mutation of pseudotuberculosis.

Human infection occurs in several ways:

• from bites of infected fleas contracted from rats;
• another reason for contracting the plague disease is contact with the skin of sick rats;
• through food contamination when food products are contaminated;
• by airborne droplets upon contact with patients with pneumonic plague.

Symptoms The incubation period lasts from 3 to 6 days. Symptoms of plague disease in the early stages are a sharp increase in temperature to 39-40 °C. Further signs of plague disease develop, such as intoxication: headache, nausea, vomiting (maybe with blood), muscle pain.

Further events can develop according to several scenarios:

• Primary septic form develops when and is characterized by an increase in symptoms of intoxication and the death of the patient from infectious-toxic shock.
• Most common cutaneous bubonic form , in which an ulcer resembling anthrax appears on the skin, and the axillary, cervical, parotid or inguinal lymph nodes turn into abscesses called buboes.
• Pulmonary form - the most severe and most often leading to death. An increase in heart rate, shortness of breath, the appearance of chest pain, cough, sputum, which gradually becomes bloody. Death occurs due to pulmonary edema.

Plague disease: treatment, complications and prevention

Treatment. The causative agent of plague is sensitive to widely used antibiotics, which should be taken as early as possible. According to indications for the treatment of plague disease, detoxification therapy, treatment of cardiac and respiratory failure, restorative therapy.

Complications. Any form of plague can become septic or pneumonic. Cerebral edema and pulmonary edema may develop. Another complication of the plague is massive bleeding, which causes death.

Prevention. A patient with suspected plague is immediately hospitalized in a specialized infectious diseases department. Contacts are quarantined for 6 days. They are given prophylactic antibiotic therapy.

It is generally accepted that the first of the 3 great plague pandemics began in the 15th year of the reign of the Roman Emperor Justinian I (it was called the “Plague of Justinian”). She ruled for about 100 years - from 531 to 650.

The second epidemic, as most scientists also agree, is known as the “Black Death.” It began in 1348 and lasted over 300 years, that is, until 1666 and the Great Fire of London. However, some historians believe that the pandemic stage lasted only 4 years. The third pandemic began in China in 1892 and ended 15 years later, according to some historians. According to others, it continued until 1959.

And some believe that even today it has not yet been exterminated: the plague bacilli and its carriers are showing increasing resistance to antibiotics and pesticides.

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• What is Plague
• What causes the Plague
• Symptoms of the Plague
• Diagnosis of Plague
• Treatment of Plague
• Prevention of Plague
• Which doctors should you contact if you have Plague?

What is Plague

Plague- an acute, especially dangerous zoonotic transmissible infection with severe intoxication and serous-hemorrhagic inflammation in the lymph nodes, lungs and other organs, as well as the possible development of sepsis.

Brief historical information
There is no other like this in the history of mankind infectious disease, which would lead to such colossal devastation and mortality among the population as the plague. Since ancient times, information has been preserved about the plague, which occurred in people in the form of epidemics with a large number deaths. It was noted that plague epidemics developed as a result of contact with sick animals. At times, the spread of the disease was pandemic-like. There are three known plague pandemics. The first, known as the Plague of Justinian, raged in Egypt and the Eastern Roman Empire from 527-565. The second, called the “great” or “black” death, in 1345-1350. covered Crimea, the Mediterranean and Western Europe; this most devastating pandemic has claimed about 60 million lives. The third pandemic began in 1895 in Hong Kong and then spread to India, where over 12 million people died. At its very beginning, important discoveries were made (the pathogen was isolated, the role of rats in the epidemiology of the plague was proven), which made it possible to organize prevention on a scientific basis. The causative agent of the plague was discovered by G.N. Minkh (1878) and independently of him A. Yersin and S. Kitazato (1894). Since the 14th century, the plague has repeatedly visited Russia in the form of epidemics. Working on outbreaks to prevent the spread of the disease and treat patients, Russian scientists D.K. made a great contribution to the study of the plague. Zabolotny, N.N. Klodnitsky, I.I. Mechnikov, N.F. Gamaleya and others. In the 20th century N.N. Zhukov-Verezhnikov, E.I. Korobkova and G.P. Rudnev developed the principles of pathogenesis, diagnosis and treatment of plague patients, and also created an anti-plague vaccine.

What causes the Plague

The causative agent is a gram-negative non-motile facultative anaerobic bacterium Y. pestis of the genus Yersinia of the Enterobacteriaceae family. In many morphological and biochemical characteristics, the plague bacillus is similar to the pathogens of pseudotuberculosis, yersiniosis, tularemia and pasteurellosis, which cause severe diseases in both rodents and humans. It is distinguished by pronounced polymorphism, the most typical are ovoid rods that stain bipolarly. There are several subspecies of the pathogen, differing in virulence. Grows on regular nutrient media with the addition of hemolyzed blood or sodium sulfite to stimulate growth. Contains more than 30 antigens, exo- and endotoxins. Capsules protect bacteria from absorption by polymorphonuclear leukocytes, and V- and W-antigens protect them from lysis in the cytoplasm of phagocytes, which ensures their intracellular reproduction. The causative agent of plague is well preserved in the excreta of patients and objects of the external environment (in the pus of a bubo it persists for 20-30 days, in the corpses of people, camels, rodents - up to 60 days), but is highly sensitive to sun rays, atmospheric oxygen, elevated temperature, environmental reactions (especially acidic), chemicals (including disinfectants). Under the influence of mercuric chloride at a dilution of 1:1000, it dies in 1-2 minutes. Well tolerated low temperatures, freezing.

A sick person can, under certain conditions, become a source of infection: with the development pneumonic plague, direct contact with the purulent contents of the plague bubo, as well as as a result of flea infection on a patient with plague septicemia. The corpses of people who died from the plague are often the direct cause of infection of others. Patients with pneumonic plague are especially dangerous.

Transmission mechanism diverse, most often transmissible, but airborne droplets are also possible (with pneumonic forms of plague, infection in laboratory conditions). The carriers of the pathogen are fleas (about 100 species) and some types of ticks, which support the epizootic process in nature and transmit the pathogen to synanthropic rodents, camels, cats and dogs, which can carry infected fleas to human habitation. A person becomes infected not so much through a flea bite as after rubbing its feces or masses regurgitated during feeding into the skin. Bacteria that multiply in the intestines of a flea secrete coagulase, which forms a “plug” (plague block) that prevents the flow of blood into its body. Attempts by a hungry insect to suck blood are accompanied by regurgitation of infected masses onto the surface of the skin at the site of the bite. These fleas are hungry and often try to suck the animal's blood. The contagiousness of fleas lasts on average about 7 weeks, and according to some data - up to 1 year.

Contact (through damaged skin and mucous membranes) when cutting carcasses and processing the skins of killed infected animals (hares, foxes, saigas, camels, etc.) and nutritional (by eating their meat) routes of plague infection are possible.

The natural susceptibility of people is very high, absolute in all age groups and through any route of infection. After an illness, relative immunity develops, which does not protect against re-infection. Repeated cases of the disease are not uncommon and are no less severe than the primary ones.

Basic epidemiological signs. Natural foci of plague occupy 6-7% of the globe's land mass and are registered on all continents, excluding Australia and Antarctica. Every year, several hundred cases of plague in humans are recorded worldwide. In the CIS countries, 43 natural plague foci have been identified with a total area of ​​more than 216 million hectares, located in lowland (steppe, semi-desert, desert) and high-mountain regions. There are two types of natural foci: foci of “wild” and foci of rat plague. In natural foci, plague manifests itself as an epizootic among rodents and lagomorphs. Infection from rodents that do not sleep in winter (marmots, gophers, etc.) occurs in the warm season, while from rodents and lagomorphs that do not sleep in winter (gerbils, voles, pikas, etc.), infection has two seasonal peaks, which is associated with breeding periods animals. Men get sick more often than women due to professional activities and stay in a natural plague focus (transhumance, hunting). In anthropurgic foci, the role of infection reservoir is performed by black and gray rats. The epidemiology of bubonic and pneumonic plague has significant differences in its most important features. Bubonic plague is characterized by a relatively slow increase in diseases, while pneumonic plague, due to the easy transmission of bacteria, can develop in a short time wide use. Patients with the bubonic form of plague are low-contagious and practically non-infectious, since their secretions do not contain pathogens, and there are few or no pathogens in the material from the opened buboes. When the disease passes into the septic form, as well as when the bubonic form is complicated by secondary pneumonia, when the pathogen can be transmitted by airborne droplets, severe epidemics of primary pneumonic plague develop with very high contagiousness. Typically, pneumonic plague follows bubonic plague, spreads along with it and quickly becomes the leading epidemiological and clinical form. Recently, the idea that the causative agent of plague can for a long time be in the soil in an uncultivated state. Primary infection of rodents can occur when digging holes in infected areas of soil. This hypothesis is based both on experimental studies and observations on the futility of searching for the pathogen among rodents and their fleas during inter-epizootic periods.

Pathogenesis (what happens?) during the Plague

Human adaptation mechanisms are practically not adapted to resist the introduction and development of the plague bacillus in the body. This is explained by the fact that the plague bacillus multiplies very quickly; bacteria produce large quantities of permeability factors (neuraminidase, fibrinolysin, pesticin), antiphagins that suppress phagocytosis (F1, HMWPs, V/W-Ar, PH6-Ag), which contributes to rapid and massive lymphogenous and hematogenous dissemination primarily into mononuclear organs phagocytic system with its subsequent activation. Massive antigenemia, the release of inflammatory mediators, including shockogenic cytokines, leads to the development of microcirculatory disorders, DIC syndrome, followed by infectious-toxic shock.

The clinical picture of the disease is largely determined by the place of introduction of the pathogen penetrating through skin, lungs or gastrointestinal tract.

The pathogenesis of plague includes three stages. First, the pathogen disseminates lymphogenously from the site of introduction to the lymph nodes, where it lingers for a short time. In this case, a plague bubo is formed with the development of inflammatory, hemorrhagic and necrotic changes in the lymph nodes. The bacteria then quickly enter the bloodstream. At the stage of bacteremia, severe toxicosis develops with changes in the rheological properties of the blood, microcirculation disorders and hemorrhagic manifestations in various organs. And finally, after the pathogen overcomes the reticulohistiocytic barrier, it disseminates to various organs and systems with the development of sepsis.

Microcirculatory disorders cause changes in the heart muscle and blood vessels, as well as in the adrenal glands, which causes acute cardiovascular failure.

With the aerogenic route of infection, the alveoli are affected, and an inflammatory process with elements of necrosis develops in them. Subsequent bacteremia is accompanied by intense toxicosis and the development of septic-hemorrhagic manifestations in various organs and tissues.

The antibody response to plague is weak and is formed in late dates diseases.

Symptoms of the Plague

The incubation period is 3-6 days (in epidemics or septic forms it is reduced to 1-2 days); The maximum incubation period is 9 days.

Characteristic acute onset illness, expressed by a rapid increase in body temperature to high numbers with stunning chills and development severe intoxication. Patient complaints of pain in the sacrum, muscles and joints are typical, headache. Vomiting (often bloody) and excruciating thirst occur. Already from the first hours of the disease, psychomotor agitation develops. Patients are restless, overly active, try to run (“runs like crazy”), they experience hallucinations and delusions. Speech becomes slurred and gait is unsteady. In more rare cases, lethargy, apathy are possible, and weakness reaches such a degree that the patient cannot get out of bed. Externally, hyperemia and puffiness of the face and scleral injection are noted. There is an expression of suffering or horror on the face (“plague mask”). In more severe cases, a hemorrhagic rash may appear on the skin. Very characteristic signs of the disease are thickening and coating of the tongue with a thick white coating (“chalky tongue”). From the outside of cardio-vascular system note pronounced tachycardia (up to embryocardia), arrhythmia and progressive fall blood pressure. Even with local forms of the disease, tachypnea, as well as oliguria or anuria, develop.

This symptomatology manifests itself, especially in the initial period, in all forms of plague.

According to the clinical classification of plague proposed by G.P. Rudnev (1970), distinguish local forms of the disease (cutaneous, bubonic, cutaneous-bubonic), generalized forms (primary septic and secondary septic), externally disseminated forms (primary pulmonary, secondary pulmonary and intestinal).

Skin form. The formation of a carbuncle at the site of introduction of the pathogen is characteristic. Initially, a sharply painful pustule with dark red contents appears on the skin; it is localized on the edematous subcutaneous tissue and is surrounded by a zone of infiltration and hyperemia. After opening the pustule, an ulcer with a yellowish bottom is formed, which tends to increase in size. Subsequently, the bottom of the ulcer is covered with a black scab, after which scarring is formed.

Bubonic form. The most common form of plague. Characterized by damage to lymph nodes regional to the site of introduction of the pathogen - inguinal, less often axillary and very rarely cervical. Usually the buboes are single, less often multiple. Against the background of severe intoxication, pain occurs in the area of ​​​​the future localization of the bubo. After 1-2 days, you can palpate sharply painful lymph nodes, first of a hard consistency, and then softening and becoming doughy. The nodes merge into a single conglomerate, inactive due to the presence of periadenitis, fluctuating upon palpation. The duration of the height of the disease is about a week, after which a period of convalescence begins. Lymph nodes can resolve on their own or become ulcerated and sclerotic due to serous-hemorrhagic inflammation and necrosis.

Cutaneous bubonic form. It is a combination of skin lesions and changes in the lymph nodes.

These local forms of the disease can develop into secondary plague sepsis and secondary pneumonia. Their clinical characteristics do not differ from primary septic and primary pulmonary forms of plague, respectively.

Primary septic form. It occurs after a short incubation period of 1-2 days and is characterized by lightning-fast development of intoxication, hemorrhagic manifestations (hemorrhages in the skin and mucous membranes, gastrointestinal and renal bleeding), and the rapid formation of a clinical picture of infectious-toxic shock. Without treatment, it is fatal in 100% of cases.

Primary pulmonary form. Develops during aerogenic infection. The incubation period is short, from several hours to 2 days. The disease begins acutely with manifestations of the intoxication syndrome characteristic of the plague. On the 2-3rd day of illness appears coughing, there are sharp pains in chest, shortness of breath. The cough is accompanied by the release of first glassy and then liquid, foamy, bloody sputum. Physical data from the lungs are scant; X-rays show signs of focal or lobar pneumonia. Cardiovascular insufficiency increases, expressed in tachycardia and a progressive drop in blood pressure, and the development of cyanosis. In the terminal stage, patients develop first soporous state, accompanied by increased shortness of breath and hemorrhagic manifestations in the form of petechiae or extensive hemorrhages, and then coma.

Intestinal form. Against the background of intoxication syndrome, patients experience severe abdominal pain, repeated vomiting and diarrhea with tenesmus and copious mucous-bloody stools. Because the intestinal manifestations can be observed in other forms of the disease; until recently, the existence of intestinal plague as an independent form, apparently associated with enteral infection, remains controversial.

Differential diagnosis
Cutaneous, bubonic and cutaneous bubonic forms of plague should be distinguished from tularemia, carbuncles, various lymphadenopathy, pulmonary and septic forms - from inflammatory diseases lungs and sepsis, including meningococcal etiology.

With all forms of plague, already in the initial period, rapidly increasing signs are alarming severe intoxication: high body temperature, tremendous chills, vomiting, excruciating thirst, psychomotor agitation, restlessness, delirium and hallucinations. When examining patients, attention is drawn to slurred speech, an unsteady gait, a puffy, hyperemic face with scleral injection, an expression of suffering or horror (“plague mask”), and a “chalky tongue.” Signs of cardiovascular failure, tachypnea rapidly increase, and oliguria progresses.

Cutaneous, bubonic and cutaneous bubonic forms of plague are characterized by severe pain at the site of the lesion, stages in the development of the carbuncle (pustule - ulcer - black scab - scar), pronounced phenomena of periadenitis during the formation of the plague bubo.

Pulmonary and septic forms are distinguished by the lightning-fast development of severe intoxication, pronounced manifestations of hemorrhagic syndrome, and infectious-toxic shock. If the lungs are affected, sharp pain in the chest and severe cough, separation of glassy and then liquid foamy bloody sputum are noted. The scanty physical data do not correspond to the general extremely serious condition.

Diagnosis of Plague

Laboratory diagnostics
Based on the use of microbiological, immunoserological, biological and genetic methods. The hemogram shows leukocytosis, neutrophilia with a shift to the left, and an increase in ESR. Isolation of the pathogen is carried out in specialized high-security laboratories for working with pathogens of particularly dangerous infections. Studies are carried out to confirm clinically significant cases of the disease, as well as to examine people with elevated temperature bodies located at the site of infection. Material from the sick and dead is subjected to bacteriological examination: punctates from buboes and carbuncles, discharge from ulcers, sputum and mucus from the oropharynx, blood. The passage is carried out on laboratory animals (guinea pigs, white mice), which die on the 5-7th day after infection.

Among the serological methods used are RNGA, RNAT, RNAG and RTPGA, ELISA.

Positive PCR results 5-6 hours after its administration indicate the presence of specific DNA of the plague microbe and confirm the preliminary diagnosis. The final confirmation of the plague etiology of the disease is the isolation of a pure culture of the pathogen and its identification.

Treatment of Plague

Plague patients are treated only in inpatient conditions. The choice of drugs for etiotropic therapy, their doses and regimens of use is determined by the form of the disease. The course of etiotropic therapy for all forms of the disease is 7-10 days. In this case the following is used:
for the skin form - cotrimoxazole 4 tablets per day;
for the bubonic form - chloramphenicol at a dose of 80 mg/kg/day and at the same time streptomycin at a dose of 50 mg/kg/day; drugs are administered intravenously; Tetracycline is also effective;
in pulmonary and septic forms of the disease, the combination of chloramphenicol with streptomycin is supplemented with the administration of doxycycline at a dose of 0.3 g/day or tetracycline at a dose of 4-6 g/day orally.

At the same time, massive detoxification therapy is carried out (fresh frozen plasma, albumin, rheopolyglucin, hemodez, intravenous crystalloid solutions, extracorporeal detoxification methods), drugs are prescribed to improve microcirculation and repair (trental in combination with solcoseryl, picamilon), forcing diuresis, as well as cardiac glycosides, vascular and respiratory analeptics, antipyretics and symptomatic agents.

The success of treatment depends on the timeliness of therapy. Etiotropic drugs are prescribed at the first suspicion of plague, based on clinical and epidemiological data.

Prevention of Plague

Epidemiological surveillance
The volume, nature and direction of preventive measures are determined by the forecast of the epizootic and epidemic situation regarding plague in specific natural foci, taking into account data on tracking the movement of morbidity in all countries of the world. All countries are required to report to WHO the emergence of plague diseases, the movement of morbidity, epizootics among rodents and measures to combat infection. The country has developed and operates a system for certification of natural plague foci, which made it possible to carry out epidemiological zoning of the territory.

Indications for preventive immunization of the population are an epizootic of plague among rodents, identification of domestic animals suffering from plague, and the possibility of infection being brought in by a sick person. Depending on the epidemic situation, vaccination is carried out in a strictly defined territory to the entire population (universally) and selectively to particularly endangered contingents - persons who have permanent or temporary connections with the territories where the epizootic is observed (livestock breeders, agronomists, hunters, harvesters, geologists, archaeologists, etc.). d.). In case of detection of a plague patient, all medical and preventive institutions must have a certain supply of medicines and means of personal protection and prevention, as well as a scheme for notifying personnel and transmitting information vertically. Measures to prevent people from becoming infected with plague in enzootic areas, people working with pathogens of particularly dangerous infections, as well as preventing the spread of infection beyond the foci to other areas of the country are carried out by anti-plague and other health care institutions.

Activities in the epidemic outbreak
When a person sick with plague or suspected of this infection appears, urgent measures are taken to localize and eliminate the outbreak. The boundaries of the territory where certain restrictive measures (quarantine) are introduced are determined based on the specific epidemiological and epizootological situation, possible operating factors of infection transmission, sanitary and hygienic conditions, intensity of population migration and transport connections with other territories. The general management of all activities in the plague outbreak is carried out by the Emergency Anti-Epidemic Commission. At the same time, the anti-epidemic regime is strictly observed using anti-plague suits. Quarantine is introduced by decision of the Emergency Anti-Epidemic Commission, covering the entire territory of the outbreak.

Patients with plague and patients suspected of having this disease are hospitalized in specially organized hospitals. Transportation of a plague patient must be carried out in accordance with current sanitary rules for biological safety. Patients with bubonic plague are placed in groups of several people in a room, while patients with the pulmonary form are placed only in separate rooms. Patients with bubonic plague are discharged no earlier than 4 weeks, with pneumonic plague - no earlier than 6 weeks from the date of clinical recovery and negative results of bacteriological examination. After the patient is discharged from the hospital, he is placed under medical supervision for 3 months.

The incidence of meningococcal infection in the Russian Federation in 2018 (compared to 2017) increased by 10% (1). One of the common ways to prevent infectious diseases is vaccination. Modern conjugate vaccines are aimed at preventing the occurrence of meningococcal infection and meningococcal meningitis in children (even early age), teenagers and adults.

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Plague is a serious infectious disease that occurs with increased body temperature and damage to the lungs and lymph nodes. Often, against the background of this disease, an inflammatory process develops in all tissues of the body. The disease has a high mortality threshold.

Historical reference

In the entire history of modern mankind, there has never been such a ruthless disease as the plague. Information has reached this day that in ancient times the disease claimed lives large quantity of people. Epidemics usually began after direct contact with infected animals. Often the spread of the disease turned into a pandemic. History knows three such cases.

The first was called the Justinian Plague. This case of pandemic was recorded in Egypt (527-565). The second was called Great. The plague raged in Europe for five years, taking the lives of about 60 million people. The third pandemic occurred in Hong Kong in 1895. It later spread to India, where more than 10 million people died.

One of largest epidemics I was in France, where the famous psychic Nostradamus lived at that time. He tried to fight the Black Death with the help of herbal medicine. He mixed Florentine iris, cypress sawdust, cloves, aloe and fragrant calamus with rose petals. From the resulting mixture, the psychic made so-called pink pills. Unfortunately, the plague in Europe claimed his wife and children.

Many cities where death reigned were completely burned. Doctors, trying to help the sick, dressed in anti-plague armor (long leather cloak, mask with a long nose). Doctors placed various herbal teas. The mouth cavity was rubbed with garlic, and rags were stuck in the ears.

Why does plague develop?

Virus or illness? This disease is caused by a microorganism called Yersonina pestis. This bacterium remains viable for a long period of time. It exhibits resistance to the heating process. The plague bacterium is quite sensitive to environmental factors (oxygen, sunlight, changes in acidity).

The source of the disease is wild rodents, usually rats. In rare cases, humans act as a carrier of the bacterium.

All people have a natural susceptibility to infection. Pathology can develop against the background of infection in absolutely any way. Post-infectious immunity is relative. However, repeated cases of infection usually occur in an uncomplicated form.

What are the signs of the plague: symptoms of the disease

The incubation period of the disease ranges from 3 to approximately 6 days, but in a pandemic it can be reduced to a day. The plague begins acutely and is accompanied by sharp increase temperature, Patients complain of discomfort in the joints, vomiting with blood. In the first hours of infection, signs are observed. The person becomes overly active, he is haunted by the desire to run somewhere, then hallucinations and delusions begin to appear. The infected person cannot speak or move clearly.

From external symptoms One can note facial hyperemia. The facial expression takes on a characteristic pained look. The tongue gradually increases in size and appears white coating. The occurrence of tachycardia and a decrease in blood pressure are also noted.

Doctors distinguish several forms of this disease: bubonic, cutaneous, septic, pulmonary. Each option has different characteristics. We will talk about them later in this article.

Bubonic plague

Bubonic plague is the most common form of the disease. Buboes refer to specific changes in the lymph nodes. They are, as a rule, singular in nature. Initially, there is soreness in the area of ​​the lymph nodes. After 1-2 days they increase in size, acquire a dough-like consistency, and the temperature rises sharply. The further course of the disease can lead to either spontaneous resorption of the bubo or the formation of an ulcer.

Skin plague

This form of pathology is characterized by the appearance of carbuncles in the area where the pathogen has entered the body. Plague disease is accompanied by the formation of painful pustules with reddish contents on the skin. Around them there is an area of ​​infiltration and hyperemia. If you open the pustule yourself, an ulcer with yellow pus appears in its place. After some time, the bottom becomes covered with a black scab, which is gradually torn away, leaving behind scars.

Pneumonic plague

Pneumonic plague is the most dangerous form disease from an epidemic point of view. The incubation period ranges from several hours to two days. On the second day after infection, a severe cough appears, pain in the chest area, and shortness of breath occur. An x-ray shows signs of pneumonia. The cough is usually accompanied by foamy and bloody discharge. As the condition worsens, disturbances in consciousness and functioning of the main systems of internal organs are observed.

Septicemic plague

The disease is characterized by rapid development. Septicemic plague is rare pathology, which is characterized by the appearance of hemorrhages in the skin and mucous membranes. Symptoms of general intoxication gradually increase. The breakdown of bacterial cells in the blood increases the content of toxic substances. As a result, the patient's condition deteriorates sharply.

Diagnostic measures

Due to the special danger of this pathology and high susceptibility to bacteria, isolation of the pathogen is carried out exclusively in laboratory conditions. Specialists collect material from carbuncles, sputum, buboes and ulcers. Isolation of the pathogen from the blood is allowed.

Serological diagnosis is carried out using next tests: RNAG, ELISA, RNGA. It is possible to isolate pathogen DNA using PCR. Nonspecific diagnostic methods include blood and urine tests, and chest x-rays.

What treatment is required?

Patients diagnosed with plague, the symptoms of which appear within a few days, are placed in special boxes. As a rule, this is a single room, equipped with a separate toilet and always with double doors. Etiotropic therapy is carried out with antibiotics in accordance with the clinical form of the disease. The duration of treatment is usually 7-10 days.

For the cutaneous form, Co-trimoxazole is prescribed, for the bubonic form, Levomycetin is prescribed. To treat the pulmonary and septic variants of the disease, Streptomycin and Doxycycline are used.

Additionally carried out symptomatic therapy. Antipyretics are used to reduce fever. Steroid hormones are prescribed to restore blood pressure. Sometimes it is necessary to support the functioning of the lungs and replace their functions.

Forecast and consequences

Currently, provided that the doctor’s recommendations for treatment are followed, the mortality rate from plague is quite low (5-10%). Timely medical care and prevention of generalization contribute to recovery without serious health consequences. In rare cases, fulminant sepsis is diagnosed, which is difficult to treat and often leads to death.

Plague is an extremely dangerous, acute zoonotic vector-borne infection that causes severe intoxication, as well as serous-hemorrhagic inflammation in the lungs, lymph nodes and other organs, and it is often accompanied by the development.

Brief historical information

In the entire history of mankind, there has never been such a ruthless infectious disease as the plague. It devastated cities, causing record mortality rates. Information has reached our time that in ancient times plague epidemics claimed a huge number of human lives. As a rule, epidemics began after people came into contact with infected animals. Often the spread of this disease turned into a pandemic; three such cases are known.

The first pandemic, called the Justinian Plague, was recorded in Egypt and the Eastern Roman Empire in the period from 527 to 565. The second was called the “great” and “black” death; for 5 years, starting in 1345, it raged in the Mediterranean countries, Western Europe and the Crimea, taking with it about 60 million human lives. The third pandemic began in Hong Kong in 1895 and later spread to India, where more than 12 million people died.

During the last pandemic, important discoveries were made, thanks to which it became possible to prevent the disease, guided by data on the identified causative agent of the plague. It has also been proven that rats contribute to the spread of infection. In 1878, Professor G.N. Minkh discovered the causative agent of the plague; also in 1894, scientists Sh. Kitazato and A. Yersin worked on this issue.

There were plague epidemics in Russia too - starting from the 14th century, this terrible disease periodically made itself known. Many Russian scientists have made great contributions to the study of this disease. Scientists such as I. I. Mechnikov, D. K. Zabolotny, N. F. Gamaleya, N. N. Klodnitsky prevented the spread of the epidemic and treated patients. And in the 20th century, G. P. Rudnev, N. N. Zhukov-Verezhnikov and E. I. Korobkova developed the principles of diagnosis and pathogenesis of plague, and also a vaccine against this infection was created and methods of treating the disease were determined.

The causative agent of the infection is the non-motile gram-negative facultative anaerobic bacterium Y. Pestis, which belongs to the genus Yersinia and the family Enterobacteriaceae. The plague bacillus, in its biochemical and morphological characteristics, resembles the causative agents of diseases such as pseudotuberculosis, pasteurellosis, yersiniosis and tularemia - humans and rodents are susceptible to them. The pathogen is characterized by polymorphism; it has the appearance of an ovoid rod, which is bipolarly colored. There are several subspecies of this pathogen, which differ in virulence.

The growth of the pathogen occurs in a nutrient medium; to stimulate growth, it requires sodium sulfite or homolyzed blood. More than 30 antigens, as well as exo- and endotoxins, were found in the composition. Capsules prevent the absorption of bacteria by polymorphonuclear leukocytes, and V- and W-antigens protect them from lysis in the cytoplasm of phagocytes, which is why they multiply inside the cells.

The causative agent of plague is able to persist not only in infected excreta, but also various objects of the external environment contain it. For example, bubo pus can persist for 30 days, and in the corpses of rodents, camels and people - about two months. The sensitivity of the pathogen to sunlight, oxygen, high temperatures, reactions acidic environment, as well as some chemicals and disinfectants. A solution of mercuric chloride (1:1000) can destroy the pathogen in 2 minutes. But the pathogen tolerates low temperatures and freezing well.

Epidemiology

The main source of plague, as well as its reservoir, are wild rodents, of which there are about 300 species, and they are distributed everywhere. But not all animals are capable of preserving the pathogen. In every natural focus there are the main species that store and transmit the infection. Main natural sources are gophers, marmots, voles, gerbils, pikas and others. For anthropourgic centers of plague - cities, ports, the main threat is synanthropic rats. Among them we can distinguish the gray rat, which is also called pasyuk. She usually lives in the sewer systems of large cities. And also the black - Egyptian or Alexandrian rat, living in houses or on ships.

If rodents develop acute form diseases, then the animals quickly die, and the spread of infection (epizootic) stops. But some rodents, for example, marmots, gophers, tarbagans, hibernate, carry the disease in a latent form, and in the spring they become sources of plague, which is why a natural focus of infection appears in their habitat.

Infected people also become sources of plague. For example, if a person has a disease such as pneumonic plague, and also if there is contact with the pus of a bubo, or if fleas become infected from a patient with plague septicemia. Often the cause of the spread of infection is the corpses of plague patients. Of all these cases, people infected with pneumonic plague are considered especially dangerous.

You can also become infected by contact, for example, through the mucous membrane or lesions on the skin. This can happen when cutting and processing the carcasses of infected animals (hares, foxes, saigas and others), as well as when eating this meat.

People are very susceptible to infection, regardless of the method of infection and the age group to which the person belongs. If a person has suffered the plague, he has some immunity to this disease, but the possibility of re-infection is not excluded. Moreover, contracting the plague a second time is not a rare case, and the disease passes in an equally severe form.

Main epidemiological signs of plague

Foci of plague in nature can occupy about 7% of the land mass, and have been recorded on almost all continents (the only exceptions are Australia and Antarctica). Every year, the plague infects several hundred people around the world. 43 natural foci have been identified in the CIS, covering an area of ​​at least 216 million hectares. The outbreaks are located on plains - desert, steppe, and in highlands.

Natural foci are divided into two types: “wild” and rat plague. Under natural conditions, plague takes the form of an epizootic of rodents and lagomorphs. Rodents that hibernate in winter carry the disease into the warmer months (spring), and animals that do not hibernate contribute to the formation of two seasonal peaks of plague, which occur during their active reproduction. As a rule, men are more likely to become infected with the plague - this is explained by the fact that they are forced to stay in the natural focus of the plague more often (activities related to hunting, animal husbandry). In urban conditions, rats - gray and black - take on the role of carriers.

If we compare the epidemiology of two types of plague - bubonic and pneumonic, significant differences can be noted. First of all, bubonic plague develops quite slowly, and the pneumonic form can spread very widely in a very short time - this is due to the easy transmission of bacteria. People suffering from bubonic plague are almost non-infectious and low-contagious. There are no pathogens in their secretions, and there are quite a few of them in the pus of buboes.

If the disease has passed into a septic form or the bubonic plague is complicated by secondary pneumonia, which allows the pathogen to be transmitted by airborne droplets, epidemics of primary type pneumonic plague begin, characterized by a high degree of contagiousness. Most often, pneumonic plague appears after bubonic plague, then spreads along with it and very quickly becomes the leading epidemiological and clinical form.

There is an opinion that the infectious agent is capable of remaining in the soil, remaining in an uncultivated state for a long time. At the same time, rodents that dig holes in contaminated soils receive primary infection. Scientists confirm this hypothesis by experimental studies, as well as by searching for the causative agent of plague among rodents during inter-epizootic periods, the ineffectiveness of which allows us to draw some conclusions.

It is known that the incubation period of plague ranges from 3 to 6 days, but in epidemic conditions or in the septic form it can be reduced to 1 day. The maximum incubation period that has been recorded is 9 days.

The onset of the disease is acute, accompanied by a rapid increase in body temperature, severe chills and signs of intoxication. Patients often complain of muscle pain and pain in the sacrum and head. The person vomits (sometimes with blood) and is tormented by thirst. In the first hours of the disease, psychomotor agitation is observed. The patient becomes restless and too active, a desire to run appears (this is where the saying “runs like crazy” comes from), then hallucinations and delusions appear. The person can no longer speak clearly or walk upright. Sometimes, on the contrary, apathy and lethargy are noticed, and due to weakness the patient is unable to get out of bed.

External signs include facial puffiness, hyperemia, and scleral injection. The facial expression takes on a pained look, with a stamp of horror on it, or, as they say, “a mask of the plague.” IN severe cases a hemorrhagic rash appears on the skin. The tongue increases in size and becomes covered with a white coating resembling chalk. It is also noted that it is gradually decreasing. Even local forms of the disease are characterized by the development of anuria, oliguria, and tachypnea. These symptoms are more pronounced on initial stage diseases, but accompany all forms of plague.

In 1970, G. P. Rudnev proposed the following clinical classification plague:

local forms (bubonic, cutaneous and cutaneous-bubonic);

generalized (primary and secondary septic);

externally disseminated (primary and secondary pulmonary, as well as intestinal).

Cutaneous form

This form of the disease is characterized by its appearance in the place where the pathogen has invaded. First, a pustule forms on the skin (the appearance is accompanied by sharp pain) with dark red contents. It is located on the subcutaneous edematous tissue, around it there is a zone of hyperemia and infiltration. If the pustule is opened, an ulcer with a yellowish bottom appears in its place, increasing in size. Then this bottom is covered with a black scab, which is torn off, leaving behind scars.

Bubonic form

This is the most common form of the disease. Bubonic plague affects the lymph nodes that are closest to the site of entry of the pathogen. Usually these are inguinal nodes, sometimes axillary, and less often cervical. Most often the buboes are single, but they can also be multiple. Pain occurs at the site of the next bubo that forms, and this is accompanied by intoxication.

Lymph nodes can be palpated 1–2 days after their appearance; the hard consistency gradually changes to a softer one. The nodes unite into a sedentary conglomerate, which can fluctuate during palpation due to the presence of periadenitis. The disease develops in about 7 days, followed by a period of convalescence. Enlarged nodes can resolve, ulcerate or become sclerotic; this is facilitated by necrosis and serous-hemorrhagic inflammation.

Cutaneous bubonic form

This form represents a change in the lymph nodes and skin lesions. Local forms of the disease can develop into secondary pneumonia and secondary plague sepsis. The clinical characteristics of these forms do not differ from the primary forms of the same diseases.

The primary septic form appears with a short (1-2 days) incubation period and is accompanied by the rapid onset of intoxication, as well as hemorrhagic manifestations - gastrointestinal or renal bleeding, hemorrhages in the mucous membranes and skin. Infectious-toxic shock develops in the shortest possible time. If the disease is not treated, then death is inevitable.

The primary pulmonary form appears after aerogenic infection. It has a short incubation period - it can be several hours, maximum two days. The disease develops acutely, first there is an intoxication syndrome. On the second or third day, cough and pain in the chest area, shortness of breath appear. When vitreous (initially), and then liquid foamy sputum with blood is released.

The obtained physical data of the lungs are extremely scarce; the x-ray shows signs of lobar or focal pneumonia. Cardiovascular insufficiency increases, which is expressed in tachycardia and a gradual decrease in blood pressure, cyanosis develops. On terminal stage patients enter a stuporous state, which is accompanied by shortness of breath, hemorrhagic manifestations(extensive hemorrhages), after which the person falls into a coma.

In the intestinal form, patients experience severe intoxication, and at the same time sharp pain in the abdomen, constant and accompanied by tenesmus. Mucous and bloody discharge are visible in the stool. Other forms of plague are also characterized by similar manifestations (probably due to enteral infection), so the question of the existence intestinal form this disease as an independent disease remains controversial.

Differential diagnosis

Various forms of plague - bubonic, cutaneous, and cutaneous bubonic - must be distinguished from diseases such as lymphadenopathy, and from carbuncles. And the septic and pulmonary forms may have symptoms reminiscent of lung disease, sepsis, and meningococcal etiology.

All forms of plague are characterized by severe intoxication, progressive signs of which appear at the very beginning of the disease. A person’s temperature rises, chills appear, he vomits, and is tormented by thirst. Psychomotor agitation, anxiety, hallucinations and delusions are also alarming. On examination, slurred speech is revealed, unsure gait, the face becomes puffy, an expression of suffering and horror appears on it, the tongue becomes white. Cardiovascular failure, oliguria, and tachypnea develop.

Cutaneous and bubonic forms of plague can be identified by sharp pain in the affected areas, it is easy to determine the stages of development of the carbuncle (first a pustule, then an ulcer, then a black scab and scar); when a bubo forms, periadenitis is observed.

Pulmonary and septic forms are accompanied by extremely rapid development of intoxication, as well as manifestations of hemorrhagic syndrome and infectious-toxic shock. Damage to the lungs is accompanied by sharp pain in the chest and a severe cough with glassy, ​​and then foamy sputum with blood. Physical findings often do not correspond to the patient's noticeable serious condition.

Laboratory diagnostics

This type of diagnosis is based on the use of biological and microbiological, immunoserological and genetic methods. The hemogram shows leukocytosis and neutrophilia with a shift to the left, as well as an increase in ESR. The pathogen is isolated in high-security specialized laboratories created specifically to work with pathogens of the most dangerous infections. Research is being conducted to confirm clinically significant cases of plague and are examining people who are in the center of infection and whose body temperature is higher than normal. Material taken from patients with plague or those who died from this disease is subjected to bacteriological analysis. Punctures are taken from carbuncles and buboes, and ulcer compartments, sputum, mucus and blood are also examined. They conduct experiments with laboratory animals, which can live for about 7 days after being infected with the plague.

As for serological methods, RNAG, RNGA, RNAT, RTPGA, ELISA are used. If PCR gives a positive result, then 6 hours after testing we can talk about the presence of DNA of the plague microbe and confirm the preliminary diagnosis. To finally confirm the presence of the etiology of the plague, a pure culture of the pathogen is isolated and identified.

Patients can be treated exclusively in a hospital setting. Drugs for etiotropic therapy, their doses, and treatment regimens are determined depending on the form of the disease. Typically, the course of therapy is from 7 to 10 days, regardless of the form of the disease. In this case they use the following drugs:

cutaneous form – cotrimoxazole (4 tablets per day);

bubonic form - chloramphenicol (dose: 80 mg/kg per day) and streptomycin (dose: 50 mg/kg per day) is used at the same time. The drugs are administered intravenously. The effectiveness of tetracycline has been noted;

pulmonary and septic forms - a combination of chloramphenicol with streptomycin + doxycycline (dose: 0.3 grams per day) or tetracycline (4-6 g/day), taken orally.

Along with this, massive detoxification therapy is carried out: albumin, fresh frozen plasma, rheopolyglucin, intravenous crystalloid solutions, hemodez, extracorporeal detoxification methods. Drugs are prescribed that help improve microcirculation: picamilon, trental in combination with solcoseryl. Forcing diuresis, cardiac glycosides, as well as respiratory and vascular analeptics, symptomatic and antipyretic drugs.

As a rule, the success of the treatment depends on how timely the therapy was carried out. Etiotropic drugs are usually prescribed at the first suspicion of plague, based on clinical and epidemiological data.

Epidemiological surveillance

The forecast of the epidemic and epizootic situation in individual natural foci determines the nature, direction and scope of measures to prevent the disease. This takes into account data obtained from monitoring the increase in the number of people infected with the plague around the world. All countries must report cases of plague, movement of infection, epizootics among animals, as well as pre-existing conditions to WHO. measures taken ah in the fight against the disease. Typically, a country develops a certification system that records natural plague foci and allows for zoning of territory in accordance with the scale of the epidemic.

Preventive actions

If an epizootic of plague is noticed in rodents or cases of the disease are detected among domestic animals, and also if the infection is likely to be imported by an infected person, preventive immunization of the population is carried out. Vaccination can be carried out universally or selectively - to individuals who have connections with those territories where the epizootic exists (hunters, agronomists, geologists, archaeologists). All medical and preventive institutions should have a supply of medicines, as well as protective and preventive means, and it is necessary to develop a scheme for transmitting information and alerting staff. Preventive measures in enzootic areas, as well as for persons who are in contact with pathogens of dangerous infections, are carried out by various anti-plague and many other health care institutions.

Activities in the epidemic outbreak

If a case of plague has been identified, or there is suspicion that a person is a carrier of this infection, urgent measures must be taken to localize and eliminate the outbreak. Based on the epidemiological or epizootological situation, the size of the territory in which restrictive measures - quarantine - must be introduced is determined. They also take into account possible operating factors through which the infection can be transmitted, sanitary and hygienic conditions, the number of migrating people and transport links with nearby areas.

The Emergency Anti-Epidemic Commission is in charge of activities in the area of ​​the outbreak. The anti-epidemic regime must be strictly observed; commission employees must wear protective suits. The emergency commission makes a decision regarding the introduction of quarantine throughout the outbreak area.

Specialized hospitals are created for plague patients and persons exhibiting suspicious symptoms. Infected people are transported in a strictly defined manner, in accordance with the current regulations. sanitary rules biological safety. Those infected with bubonic plague can be housed in groups of several people in one room, while patients with the pneumonic form must be distributed into separate rooms. A person who has suffered bubonic plague can be discharged no less than 4 weeks after clinical recovery (negative bacteriological test results). With pneumonic plague, a person must stay in the hospital after recovery for at least 6 weeks. After the patient leaves the hospital, he is monitored for 3 months.

The source of infection is subject to thorough disinfection (current and final). Those persons who came into contact with infected people, their things, corpses, as well as participants in the slaughter of sick animals, are isolated for 6 days and are subject to medical supervision. In the case of pneumonic plague, it is necessary to individually isolate for 6 days all persons who may have become infected and provide them with prophylactic antibiotics (rifampicin, streptomycin, etc.).

Education: in 2008, he received a diploma in the specialty “General Medicine (Medicine and Prophylactic Care)” at the Russian Research Institute medical university named after N.I. Pirogov. I immediately completed an internship and received a diploma as a therapist.

Plague is a potentially serious infectious disease caused by the plague bacillus, pathogenic for humans and animals. Before the invention of antibiotics, the disease caused a very high mortality rate and Medieval Europe irrevocably changed the social and economic structure of society.

Great pandemics

The plague has left an indelible dark mark on the history of mankind, and it is not without reason that many peoples associate it with death. Even a brief summary of the misfortunes suffered can take several volumes, but the history goes back thousands of years.

Ancient sources indicate that the disease was known in North Africa and the Middle East. It is assumed that this is what is described in the biblical book of Kings as a pestilence. But indisputable proof of its early existence is the DNA analysis of Bronze Age people, confirming the presence of the plague bacillus in Asia and Europe between 3 thousand and 800 BC. Unfortunately, the nature of these outbreaks cannot be verified.

During the time of Justinian

The first reliably confirmed pandemic occurred during the reign of the Byzantine Emperor Justinian in the 6th century AD.

According to historian Procopius and other sources, the outbreak began in Egypt and moved along maritime trade routes, striking Constantinople in 542. There, the disease claimed tens of thousands of lives in a short period of time, and the death rate grew so quickly that the authorities had problems getting rid of the corpses.

Judging by the descriptions of the symptoms and modes of transmission of the disease, it is likely that all forms of plague were raging in Constantinople at the same time. Over the next 50 years, the pandemic spread west to Mediterranean port cities and east to Persia. Christian authors, for example, John of Ephesus, considered the cause of the epidemic to be the wrath of God, and modern researchers are confident that it was caused by rats (constant passengers on sea ships) and the unsanitary living conditions of that era.

Black Death of Europe

The next pandemic hit Europe in the 14th century and was even more terrible than the previous one. The death toll reached, according to various sources, from 2/3 to ¾ of the population in the affected countries. There is evidence that in times of revelry Black Death about 25 million people died, although determining the exact amount is currently impossible. The plague, like last time, was brought by merchants on ships. Researchers suggest that the disease came to the southern ports of what is now France and Italy from the Genoese colonies of Crimea, spreading from Central Asia.

The consequences of this catastrophe not only left an imprint on the religious and mystical characteristics of the Europeans’ worldview, but also led to a change in the socio-economic formation.

The peasants who made up the main workforce became critically small. To maintain the same standard of living, it was necessary to increase labor productivity and change the technological structure. This need gave impetus to the development of capitalist relations in feudal society.

Great Plague of London

Over the next three centuries, small outbreaks of the disease were observed across the continent from the British Isles to Russia. Another epidemic broke out in London in 1664-1666. The number of deaths is expected to be between 75 and 100 thousand people. The plague spread rapidly:

• in 1666-1670 - in Cologne and throughout the Rhine Valley;
• in 1667-1669 - in the Netherlands;
• in 1675−1684 - in Poland, Hungary, Austria, Germany, Turkey and North Africa;

Briefly about the losses: in Malta - 11 thousand people died, in Vienna - 76 thousand, in Prague - 83 thousand. By the end of the 17th century, the epidemic began to gradually subside. The last outbreak was in the port city of Marseille in 1720, where it killed 40,000 people. After this, the disease was not recorded in Europe (with the exception of the Caucasus).

The decline of the pandemic can be explained by progress in sanitation and the use of quarantine measures, the fight against rats as carriers of the plague, and the abandonment of old trade routes. During the outbreaks in Europe, the causes of the disease were not well understood medical point vision. In 1768, the first edition of the Encyclopædia Britannica published the popular scientific opinion among contemporaries that plague fever arose from “poisonous miasma” or vapors carried from eastern countries with air.

The best treatment was considered to be expulsion of the "poison", which was achieved either by natural rupture of the tumors or, if necessary, by incising and draining them. Other recommended remedies were:

• bloodletting;
• vomit;
• sweating;
• purgation.

During the 18th and early 19th centuries. the plague was recorded in the countries of the Middle East and North Africa, and in 1815−1836. appears in India. But these were only the first sparks of a new pandemic.

Latest in modern times

Having crossed the Himalayas and gained momentum in the Chinese province of Yunnan, in 1894 the plague reached Guangzhou and Hong Kong. These port cities became distribution centers for the new epidemic, which by 1922 was being imported by shipping throughout the world, more widely than in any previous era. As a result, about 10 million people from a variety of cities and countries died:

Almost all European ports were hit, but of the affected regions, India found itself in the worst situation. Only towards the end of the 19th century did the germ theory develop, and it was finally established which pathogen was responsible for so many deaths. All that remains is to determine how the bacillus infects humans. It has long been observed that in many epidemic areas unusual deaths of rats precede outbreaks of plague. The disease appeared in people some time later.

In 1897, the Japanese doctor Ogata Masanori, examining the outbreak of the disease on the island of Farmosa, proved that the plague bacillus was carried by rats. The following year, the Frenchman Paul-Louis Simon demonstrated the results of experiments that showed that fleas of the species Xenopsylla cheopis were carriers of plague in the rat population. This is how the routes of human infection were finally described.

Since then, measures have been taken around the world to exterminate rats in ports and on ships, and insecticides have been used to poison rodents in areas of outbreaks. Since the 1930s, doctors have used sulfur-containing drugs to treat the population, and later antibiotics. The effectiveness of the measures taken is evidenced by the reduction in the number of deaths over the next decades.

Particularly dangerous infection

Plague is one of the deadliest diseases in human history. The human body is extremely susceptible to the disease, infection can occur both directly and indirectly. A defeated plague may emerge after decades of silence with even greater epidemic potential and significantly affect the population of entire regions. Due to its easy spread, it, along with botulism, smallpox, tularemia and viral hemorrhagic fevers(Ebola and Marburg) are included in group A of bioterrorism threats.

Methods of infection

The causative agent of plague is Y. pestis, a nonmotile rod-shaped anaerobic bacterium with bipolar staining, capable of producing an antiphagocytic mucous membrane. Closest relatives:

The resistance of the plague pathogen to the external environment is low. Drying, sunlight, competition with putrefactive microbes kills it. Boiling a stick in water for a minute leads to its death. But it is able to survive on wet linen, clothes with sputum, pus and blood, and is stored for a long time in water and food.

IN wildlife And rural areas Most of the spread of Y. pestis occurs through transmission between rodents and fleas. In cities, the main carriers are synanthropic rodents, primarily gray and brown rats.

The plague bacterium easily migrates from the urban environment to nature and back. It is usually transmitted to humans through the bites of infected fleas. But there is also information about more than 200 species of mammals (including dogs and cats) that can be carriers of the stick. Half of them are rodents and lagomorphs.

That's why The main rules of conduct in areas at risk of a disease outbreak will be:

• avoiding contact with wild animals;
• Be careful when feeding rodents and rabbits.

Pathogenesis and forms of the disease

The plague bacillus is characterized by a surprisingly stable and strong ability to multiply in the tissues of the host and lead to his death. After entering the human body, Y. pestis migrates along lymphatic system to the lymph nodes. There, the bacillus begins to produce proteins that disrupt the inflammatory reactions, blocking the fight of macrophages against infection.

Thus, the host's immune response is weakened, bacteria quickly colonize the lymph nodes, causing painful swelling, and eventually destroying the affected tissue. Sometimes they enter the bloodstream, leading to blood poisoning. During pathological and anatomical studies, their accumulations are found in the following organs:

• in the lymph nodes;
• spleen;
• in the bone marrow;
• liver.

The disease in humans has three clinical forms: bubonic, pulmonary and septic. Pandemics are most often caused by the first two. Bubonic without treatment turns into septic or pulmonary. Clinical manifestations for these three types look like this:

Treatment and prognosis

Whenever a diagnosis of plague is suspected on clinical and epidemiological grounds, appropriate specimens for diagnosis should be obtained immediately. Antibacterial therapy prescribed without waiting for a response from the laboratory. Suspicious patients with signs of pneumonia are isolated and treated with airborne precautions. The most applicable schemes:

Other classes of antibiotics (penicillins, cephalosporins, macrolides) have had varying success in treating this disease. Their use is ineffective and questionable. During therapy, it is necessary to provide for the possibility of complications such as sepsis. With absence medical care The forecasts are not encouraging:

• pulmonary form - mortality 100%;
• bubonic - from 50 to 60%;
• septic - 100%.

Medicines for children and pregnant women

With proper and early treatment, complications of plague during pregnancy can be prevented. In this case the choice of antibiotics is based on an analysis of the side effects of the most effective drugs:

Experience has shown that a properly prescribed aminoglycoside is the most effective and safe for both the mother and the fetus. It is also recommended for use in the treatment of children. Due to its relative safety and the possibility of intravenous and intramuscular administration, gentamicin is the preferred antibiotic for the treatment of children and pregnant women.

Preventive therapy

Persons who are in personal contact with persons with pneumonia or persons who are likely to have been exposed to fleas infected with Y. pestis, have had direct contact with body fluids or tissues of an infected mammal, or have been exposed to infection during laboratory research infectious materials must undergo antibacterial prophylactic therapy if contact occurred in the previous 6 days. The preferred antimicrobial agents for this purpose are tetracycline, chloramphenicol or one of the effective sulfonamides.

Administration of an antibiotic before infection may be indicated in cases where people must remain in plague-prone areas for short periods. This also applies to being in an environment where infection is difficult or impossible to prevent.

Precautionary measures for hospitals include a quarantine regime for all cases of plague. These include:

In addition, a patient with suspected pneumonic plague infection should be kept in a separate room and treated with precautions regarding the possibility of airborne infection of personnel. In addition to those listed, they include restricting the patient’s movement outside the room, as well as mandatory wearing of a mask in the presence of other persons.

Possibility of vaccination

Live attenuated and formalin-killed Y. pestis vaccines are available for use in different ways around the world. They are distinguished by their immunogenic and moderately high reactivity. It is important to know that they do not protect against primary pneumonia. In general, it is not possible to vaccinate communities against epizootic impacts.

Additionally, this measure is little used during human plague outbreaks because it takes a month or more for a protective immune response to develop. The vaccine is indicated for people in direct contact with the bacterium. These may be employees of research laboratories or people studying infected animal colonies.

Distemper of carnivores

This disease (Pestis carnivorum) is known among domestic dogs as distemper and is not related to Y. pestis. It is manifested by damage to the central nervous system, inflammation of the mucous membranes of the eyes and respiratory tract. Unlike human plague, it is viral in nature.

Currently, canine plague is recorded among domestic, wild and industrially bred animals in all countries of the world. Economic damage is expressed in losses from culling and slaughter, a decrease in the volume and quality of fur, the cost of carrying out preventive measures, violation technological process growing.

The disease is caused by an RNA virus 115−160 nm in size from the Paramyxoviridae family. Dogs, foxes, arctic foxes, Ussuri raccoons, otters, jackals, hyenas and wolves are susceptible to it. For different animal species, the pathogenicity of the virus is different - from latent asymptomatic disease to acute with 100% mortality. Ferrets are the most sensitive to it. The canine distemper virus is very virulent, but does not pose a danger to humans.

Currently, the plague is a disease whose symptoms are well studied. Its foci remain in the wild and are preserved in permanent habitats of rodents. Modern statistics are as follows: throughout the world in one year, approximately 3 thousand people come into contact with this disease and about 200 of them die. Most cases occur in Central Asia and Africa.