Pneumonic plague is an acute highly contagious infectious disease with airborne transmission. It is characterized by the appearance of symptoms of severe general intoxication, signs of damage to the respiratory and cardiovascular systems, sepsis. The basis of the diagnosis is the bacteriological method and PCR, various body fluids are used for the study. Additionally, serological tests are performed. Antibacterial drugs are used as specific therapy, primarily aminoglycosides and tetracyclines. In parallel, symptomatic treatment is prescribed to correct the patient’s condition.
ICD 10
A20.2 Pneumonic plague
General information
Pneumonic plague is not a separate disease, along with bubonic is considered as one of the forms of plague. Cases of the disease are registered in many countries of Africa, Asia, South America, the Caucasus, and Altai. Currently, the most endemic regions are Madagascar, Congo, and Peru. According to WHO, 3,248 cases of the disease were registered in the world over the period 2010-2015, 584 of them with a fatal outcome. Susceptibility is high, people become infected regardless of gender and age. Men suffer more often, which is due to their greater employment in the rodent fishery, their passion for hunting. In countries with a temperate climate, the peak incidence occurs in the summer-autumn period, with a hot one – in the spring season.
Causes
The causative agent is the gram–negative bacillus Yersinia pestis. The pathogen is quite stable in the external environment. At a temperature of 22 ° C, it can remain viable for up to 4 months, at 100 ° C it is inactivated after 1 minute. Yersinia dies under the influence of solutions of lysol, sulema and carbolic acid, direct sunlight. It is sensitive to drying and antibacterial drugs. It persists in sputum and blood for up to a month.
Due to the presence of exo- and endotoxin, the bacterium has a pronounced toxic effect on the human body. Specific factors of aggression and invasion allow it to inhibit the activity of macrophages and persist in them. At 37 ° C in an infected organism, the microbe forms a capsule, as a result of which its virulence increases. The source of the disease is a person with a primary or secondary pulmonary form of plague. Transmission occurs aerogenically.
Pathogenesis
In primary infection, the entrance gate is the mucous membranes of the respiratory tract. With the lymph flow, the bacillus enters the regional lymph nodes, where it is absorbed by macrophages. Incomplete phagocytosis promotes the survival and reproduction of microbes inside phagocytes. Serous hemorrhagic inflammation occurs at the site of localization of the pathogen. The lung parenchyma becomes full-blooded, interstitial and alveolar edema is formed. The pleura is often involved in the process. Due to toxins, the vascular endothelium is damaged, stasis, blood clots, hemorrhage foci, necrosis zones are formed.
The entry of the pathogen into the blood contributes to the generalization of infection. Bacteremia occurs, secondary dropouts appear. Capillary paresis causes disorders of the cardiovascular system, kidneys and other organs. Infected people die from heart or respiratory failure. With sepsis, patients die from shock with DIC syndrome. The secondary form is caused by the introduction of yersinia into the lung tissue as a result of bacteremia, subsequently the pathological process develops as with the primary type of pathology.
Classification
As an independent disease, pneumonic plague is not isolated, it is considered a type of pathology caused by the plague bacillus. The pulmonary form is one of the most severe variants of the course of the disease, it can cause the development of epidemics, which made it possible to classify it as a particularly dangerous infection. There are the following types:
- Primary pneumonic plague. It develops when the pathogen is transmitted by aerosol in contact with a patient with a pulmonary type of infection. Characterized by a very severe course, symptoms of intoxication, pleuropneumonia with bloody liquid sputum. Bubones are rarely detected. Without appropriate treatment, death occurs on day 3-4. With a lightning-fast course, patients die in the first day.
- Secondary pneumonic plague. The patient is infected by transmissible, contact or alimentary pathways, the lungs are affected in 5-10% of cases as a result of hematogenic introduction of the pathogen. Bubons of the first and second orders are objectively detected. Against the background of clinical manifestations of the main form, the same signs of plague pneumonia appear on day 2-3 as in the primary variant. The patient becomes a source of aerogenic infection.
Pneumonic plague symptoms
The incubation period is from 3 to 10 days, on average 4-6 days, can be reduced to one day. The course of infection is conditionally divided into three periods: initial, the height of the disease and terminal. Pathology manifests suddenly with a sharp rise in body temperature to 39-40 ° C. There are symptoms of severe intoxication, headache and muscle pain, weakness, chills, vomiting. Patients complain of shortness of breath, cough with the discharge of vitreous transparent sputum. It is often bothered by cutting pain, heaviness in the chest, tachycardia, conjunctivitis.
As the disease develops, the nature of sputum changes. It becomes liquid, bloody (with an admixture of scarlet blood or rusty), with the addition of pulmonary edema – pink, foamy. The secretions contain a large amount of the pathogen. A picture of lobular or focal pleuropneumonia is formed. Scant auscultative data do not correlate with the severe condition of the patient. The hyperemia of the skin, puffiness of the face, injection of sclera vessels, the so-called “bloodshot eyes” are objectively determined. The tongue is thickly overlaid with a white coating – as if “rubbed with chalk”.
In the midst of the plague, the symptoms of a disorder of the activity of nervous structures attract attention. At the initial stages, patients are excited or inhibited. As the pathology progresses, toxic encephalopathy develops. Speech becomes slow, slurred, coordination of movements is disrupted, sensitivity to sound and light stimuli increases. Various degrees of disturbance of consciousness are formed up to coma.
As a result of paresis of the vascular bed and microcirculation disorders, deviations from the cardiovascular system, ARF occur. Cyanosis and chest pains increase, facial features sharpen, shortness of breath is detected up to 60 per minute. There is deafness of heart tones, tachycardia, pulse may be arrhythmic. The pressure drops sharply, in the terminal period it is almost not determined. Hemorrhagic syndrome joins. Areas with hemorrhages and petechiae are visible on the skin. Patients die from respiratory failure or severe hemodynamic disorders.
Secondary pneumonic plague is formed as a complication against the background of the main form of pathology. Symptoms of damage to the central nervous system, respiratory and vascular systems correspond to the above description. After the infection, a stable cellular immunity is formed, but with massive infection, re-infection is not excluded.
Complications
The most common complication of pneumonic plague is the development of acute cardiovascular and respiratory insufficiency. Episodes of infectious-toxic shock and DIC syndrome are not uncommon. Due to increased thrombosis, gangrene of the fingertips is formed, acute kidney damage is possible. Subsequent disorders of the blood clotting system contribute to massive bleeding. Toxic damage to the central nervous system is complicated by a coma, the facts of plague meningitis are described in the literature. Bacteremia and the formation of new foci in various organs lead to sepsis.
Diagnostics
The pulmonary variant of pathology is diagnosed on the basis of clinical and laboratory data. During an objective examination at the initial stages, the infectious disease doctor pays attention to the puffiness and hyperemia of the face, injection of sclera vessels, and tongue lining. There is febrile fever, cough with an admixture of blood, chest pain. During auscultation, small bubbly wet wheezes, pleural friction noise, tachypnea are heard, in cardiac points – tone deafness, tachycardia, arrhythmias. Hypotension is increasing.
In the terminal phase, cyanosis of the skin is expressed. In the case of secondary involvement of respiratory tissue, bubones are determined. The appearance of neurological symptoms as a consequence of infectious-toxic encephalopathy is characteristic. With the development of hemorrhagic syndrome, bleeding, hemorrhages in the skin and mucous membranes are detected. The following methods are used to confirm the diagnosis:
- General laboratory research. In the general blood test, leukocytosis is noted with a shift of the formula to the left, acceleration of ESR. The urine analysis reveals proteinuria and hematuria, hyaline and granular cylinders. When the DIC syndrome is attached, the changes in the coagulogram correspond to the stage of the process.
- Identification of the pathogen. The determining method in the diagnosis is the bacterioscopic method. As a material, sputum, blood, smears from the throat, punctate from bubons, separated from ulcers are used. Microscopy of smears is performed. Perform seeding of biological fluids on nutrient media. PCR is considered a fast and qualitative analysis. Additionally, ELISA, RIF, RPG are used. A biological method with the infection of laboratory animals is possible.
- Chest radiography. X-ray examination determines focal and infiltrative shadows, which confirms the presence of pneumonia. Often, the pictures show signs of pleural involvement, and effusion may be detected.
Differential diagnosis is performed with croup pneumonia. It is important to distinguish pathology from the pulmonary form of anthrax. Plague pneumonia can resemble changes in tularemia, typhoid and typhus, lung damage during influenza infection. With secondary infection, it is necessary to exclude acute purulent lymphadenitis of streptococcal and staphylococcal origin, sodoku, cat scratch disease.
Treatment
Conservative therapy
Patients with suspected plague are subject to isolation in compliance with anti-epidemic measures. The patient must observe strict bed rest. Therapy has a complex character, combines etiotropic and pathogenetic aspects. Specific etiological treatment is carried out with antibacterial drugs from the group of aminoglycosides, tetracyclines. Streptomycin is more often used intramuscularly and tetracycline intravenously. As an alternative, gentamicin, doxycycline, rifampicin, ciprofloxacin, cephalosporins are used.
With the development of meningitis, chloramphenicol is prescribed in combination with other antibiotics. The duration of the course of taking drugs is at least 10 days, then – according to indications. The management of pregnant women has some difficulties due to the undesirable effect of many medications on the fetus. The scheme of drug therapy in such cases is made taking into account possible risks, foreign experts recommend giving preference to gentamicin.
For the purpose of detoxification, infusion therapy with colloidal and crystalloid solutions with forced diuresis, plasmapheresis is prescribed. If necessary, cardiotonic agents, antipyretic drugs, glucocorticosteroids are used. Freshly frozen plasma, human albumin is injected with violations of hemostasis and protein synthesis. Proton pump inhibitors are recommended to prevent the development of stress ulcers. It is possible to introduce anti-plague serum and gamma globulin.
The addition of complications, such as pulmonary edema, sepsis, DIC syndrome, requires correction of therapeutic measures. The therapy plan includes plasma proteinase inhibitors, hemostatics, adreno- and sympathomimetics and other drugs. In case of respiratory insufficiency, inhalation of an oxygen-air mixture is necessary, according to indications, transfer to a ventilator. Additionally, B vitamins, vitamin K are used.
Surgical treatment
Surgical interventions may be required for the secondary pulmonary form of plague, accompanied by the formation of bubons. With suppuration and opening of inflamed lymph nodes, their surgical treatment is carried out. Local administration of antibiotics active to staphylococci is also used directly into the bubon after the appearance of fluctuation or spontaneous drainage.
Prognosis and prevention
The prognosis is serious. The mortality rate without therapy is 30-100%. Properly selected treatment can significantly reduce this indicator. Measures of non-specific prevention are aimed at identifying and neutralizing foci, hospitalization and isolation of infected people, veterinary supervision of animals. An important element of the fight against the spread of the plague is the destruction of rodents and fleas.
After recovery, the convalescents are registered at the dispensary for 3 months. All contact persons are subject to isolation and emergency prevention with doxycycline or streptomycin course lasting 7 days. Discharge is carried out with full clinical recovery (no earlier than 6 weeks) and only after a three-time negative bacteriological examination. Specific prevention is carried out by immunizing the population from risk groups with a dry live attenuated vaccine.