Tularemia: symptoms and treatment
Tularemia is a disease of a natural-focal character, manifested as an acute infection. Tularemia, the symptoms of which are in the defeat of lymph nodes and skin, and in some cases, mucous throat, eyes and lungs, besides this, is also marked by the symptoms of general intoxication.
The causative agent of the disease is Francisella tularensis, a gram-negative aerobic bacterium. Remarkably, tularemia bacillus is a highly microorganism, and its viability in water is possible at a temperature corresponding to 4 ° C for a month. In grain and in straw, when the temperature corresponds to zero, the microorganism’s viability may be about six months, at 20-30 degrees the survival rate of the microorganism is possible within 20 days, and in the skins of animals that died from tularemia, the bacterium can live up to a month at a temperature of 8-12 Degrees. The death of bacteria occurs in the case of exposure to high temperatures, as well as disinfectants.
Bird and wild rodents, including some mammalian species (sheep, dogs, rabbits, etc.) act as a reservoir of infection, as well as its source. The most significant contribution to the spread of this infection is observed for rodents (muskrat, voles, etc.). As for the person as an infectious agent, he is not contagious.
In the transmission of bacteria the most common is the transmissible mechanism. In this case, the microbe enters through a bite of bloodsucking or tick in the animal’s body. Characteristic for the disease by infection is infection through the bite of an ixodic tick.
Considering the prevalence of tularemia, it should be noted that the susceptibility to this disease is 100%. Most of the susceptibility to infection is observed among men, and those of them, whose profession predisposes to direct contact with animals. Foci of the territorial form in the process of migration of rodents that have been infected. In general, tularemia is relevant for rural areas, but over the past few years there has been a clear trend towards an increase in morbidity in urban settings.
A different degree of morbidity growth is observed year-round, with the appearance of the disease in its specific form for each season of the year. This is explained by etiological factors. A significant number of episodes of morbidity is observed in the autumn period, meanwhile, related to haymaking and harvesting in the fields, the transmissible outbreaks of tularemia often appear in the period July-August.
Features of transmission of the pathogen of tularemia
Below is a diagram indicating the specific features of the transmission of the disease, depending on the metamorphosis of the tick.
The number «1» indicates the infection of mite larvae through small mammals, patients with tularemia. The figure «2» determines the next cycle, in which nymphs percolating from the larvae transmit the pathogen to small mammals. «3» indicates the transfer of infectious sexually transmitted mites infected with nymphs already to large mammals.
Penetration of the pathogen occurs through the skin, and even if it is not damaged. As we have already indicated, the mucosa of the respiratory tract and the eye, as well as the gastrointestinal tract become the sites for penetration.
The area of the so-called entrance gate largely determines the clinical features of the tularemia course. Often in this area there is a development of primary affect, in which the urgency acquires a sequence of alternating spots, papules, vesicles, pustules and ulcers. Somewhat later, tularemia rods enter the region of regional lymph nodes, in which their subsequent reproduction occurs while the inflammatory process develops at the same time. It should be noted that the inflammatory process is accompanied by the formation of a primary bubo (that is, an inflamed lymph node). The death of francisell leads to the release of lipopolysaccharide complex (endotoxin), which, in turn, strengthens local inflammation and provokes the development of intoxication when it enters the blood.
With hematogenous dissemination, the development of generalized forms of infection occurs with characteristic toxic-allergic manifestations. In addition, secondary buboes are formed, various systems and organs are affected (in particular the lungs, spleen and liver). In the field of lymph nodes, as well as internal organs that have suffered defeat, a specific type of granuloma is formed in combination with the central areas with necrosis. There is also an accumulation of granulocytes, lymphoid and epithelial elements.
The incomplete process of phagocytosis predisposes to the formation of granulomas, which is determined by the characteristics of the pathogen (in particular, the factors that prevent killing inside the cells). Often the formation of granulomas in primary buboes leads to the formation of suppuration in them, followed by spontaneous dissection. Such a course of the process is characterized by a prolonged healing of the ulcer formed.
As for secondary buboes, for them, as a rule, suppuration is not a characteristic feature. When replacing necrotic sites that have arisen in the lymph nodes, a connective tissue, suppuration does not occur, buboes are sclerosed or dissolve.
The clinical classification of the considered disease distinguishes its following forms:
- According to the localization of the local process:
- bubonic tularemia
- Ulcer-bubonic tularemia
- Eye-bubonic tularemia
- An angino-bubonic tularemia
- Tularemia pulmonary;
- Abdominal tularemia
- Generalized tularemia.
- Depending on the duration of the disease:
- Acute tularemia
- Prolonged tularemia
- Recurrent tularemia
- Depending on the severity of the current:
- Tularemia is mild;
- Medium-sized tularemia
- Tularemia is severe.
The duration of the incubation period is about 1-30 days, but most often 3-7 days.
The common signs characteristic of tularemia, and, accordingly, the signs characteristic of any of its clinical forms, are manifested in an increase in temperature (up to 40 ° C) and in symptoms indicating intoxication (headache, muscle pain, chills, weakness, Anorexia — lack of appetite, which indicates its complete absence). Most often the fever has a remitting nature, and also the character is permanent, wavy or intermittent. The duration of the fever may be of the order of a week, but it is possible for it to continue for two to three months. Meanwhile, mainly its duration varies within three weeks.
The examination of patients indicates hyperemia and general pastosity of the face (i.e., whitening of the skin in combination with loss of elasticity caused by mild edema), hyperemia (reddening) of the conjunctiva is also observed. In frequent cases, the emergence of an exanthema of one kind or another (maculopapular, erythematous, vesicular, rose-oole or petechial) becomes possible. The pulse is rare, the pressure is low. After a few days after the onset of the disease, hepatolienal syndrome is noted.
It should be noted that the development of this or that clinical form of tularemia is determined on the basis of the mechanism of infection, as well as the entrance gates of the infection, which, as we noted, indicate local localization of the process. From the moment of penetration through the skin of the pathogen, a bubonic form disease develops, which manifests itself, respectively, in the form of lymphadenitis (bubo), regional to the gate infection. Lymphadenitis implies, in particular, inflammation of the lymph nodes.
In addition, a combined or isolated lesion that affects various groups of lymph nodes (inguinal, axillary, femoral) becomes possible. Hematogenous dissemination of pathogens can also contribute to the formation of secondary buboes. This is accompanied by soreness and a subsequent increase in lymph nodes, which can reach a size up to hazelnut or a small chicken egg. Gradually painful reactions in their manifestations decrease, then disappear altogether. The characteristic contours of bubo do not lose their distinctness, and insignificant manifestations of periadenitis are noted. The dynamics of tularemia is characterized by a slow resolution and suppuration with the appearance of a fistula, this is accompanied by the release of a creamy pus.
Ulcerative bubonic form. Predominantly the development of this form occurs in the case of transmissible infection. The place where the microorganism has been introduced has been characterized for several days by a succession of such formations as a spot and a papule, a vesicle and a pustule, after which a shallow type of ulcer with slightly raised edges is formed. Covered by its bottom is a crust of dark color, in form it resembles a «cockade». Parallel to this, the development of regional lymphadenitis (bubo) also occurs. In the future, the ulcer is cicatrized at a very slow rate.
When a bacterium penetrates the conjunctiva, a eyeball-shaped form is formed. This is accompanied by the defeat of the mucous eyes, which occurs according to the principle of conjunctivitis, papular-like formations, and after — erosive-ulcerative formations with the allocation of pus yellowish tinge. The process of corneal damage in this case is extremely rare. This symptomatology is accompanied by the severity of the eyelid edema, as well as regional lymphadenitis. There is a severity and duration of the disease.
Anginosis-bubonic form. Its development occurs when penetrating the pathogen through water or food. There are complaints from patients on manifestations in the form of moderate pain in the throat, difficulty swallowing. Inspection reveals flushing of the tonsils, an increase in their size, swelling. In addition, they are soldered to the fiber surrounding them. The surface of the tonsils (mostly on one side) is covered with a grayish-white necrotic coating, which is difficult to remove. There is an expression of edema of the tongue and arches. With the course of the disease, the tissues of the affected tonsils are destroyed by the formation of long-healed and sufficiently deep ulcers. The concentration of tularemia buboes encompasses the cervical, parotid and submandibular regions, which basically corresponds to the side of the almond lesion.
Abdominal form Its development is due to a lesion in the mesenteric lymph nodes. Symptom is manifested in the occurrence of severe pain in the abdomen, in some cases — vomiting and anorexia. Diarrhea is also noted for a number of cases. Palpation is determined by soreness in the navel, there is no exclusion of symptomatology indicating irritation of the peritoneum. In addition to these symptoms, hepatolyenal syndrome also occurs. Palpation of mesenteric lymph nodes is possible in rare cases, their increase is determined by using such a method of examination as ultrasound.
Pulmonary form. Its course is possible in the bronchial or pneumonic version.
- Bronchotic course. This variant is caused by the defeat of paratracheal, mediastinal and bronchial lymph nodes. It is characterized by moderate intoxication and dry cough, pain in the chest area. There are dry wheezes when listening to the lungs. As a rule, this flow is characterized by its own ease, recovery in this case occurs after 10-12 days.
- Pneumonic flow. It is characterized by an acute onset, the course of the disease in this form is debilitating and sluggish, for a long time the accompanying symptom is fever. Formed in the lungs pathology has manifestations in the form of focal pneumonia. Pneumonia is distinguished by severity and acyclicity of its course, as well as a tendency to the subsequent development of complications (segmental, lobular or disseminated pneumonia with a characteristic increase in the lymph nodes of a given group, as well as pleurisy and cavities, including gangrene of the lungs).
The form is generalized. Its clinical manifestations are similar to typhoid paratyphoid infections or severe sepsis. Fever is characterized by the intensity of its manifestations and its long-term preservation. The symptoms of intoxication are also very pronounced (chills, headache, weakness, pain in the muscles). There is a lability (variability) of the pulse, deafness of heart sounds, low blood pressure. In the vast majority of cases, the first days of the disease occur with the development of hepatolyenal syndrome. Later, it becomes possible to form an exanthema of persistent rosaceous petechial character when localizing the characteristic rash elements in the region of symmetrical parts of the body (hands, forearm, foot, shin, etc.). This form does not exclude the possibility of developing secondary buboes, which are caused by dissemination (spread) of the pathogen, as well as dissemination of specific metastatic pneumonia.
Complications of tularemia
Predominantly their relevance can be said in the case of the development of a generalized form. Most often there are tularemia pneumonia of a secondary type, often a shock of an infectious-toxic character is formed. Rare cases are noted by the occurrence of meningitis, myocarditis, meningoencephalitis, polyarthritis and other pathologies.
Diagnosis of Tularemia
The use of nonspecific laboratory techniques (urine, blood tests), determines the presence of signs characteristic of inflammation and intoxication. The disease in the first days of its course manifests itself in neutrophilic leukocytosis in the blood, then a drop in the total number of leukocytes is observed. Simultaneously with this increase the concentration of fractions of monocytes and lymphocytes is exposed.
Serological specific type of diagnosis is performed using RNGA and RA. Progression of the disease is characterized by an increase in antibody titer. The definition of tularemia is already possible on the 6th-10th day from the time it began, for which immunofluorescence analysis (ELISA) is used. This serological test with respect to diagnosing tularemia is most sensitive. As for the possibility of an earlier diagnosis of the disease (its first days), it is possible with PCR.
Very specific and, at the same time, rapid diagnosis is performed using a skin-allergic test, which is performed with the use of tularemic toxin. The result is already determined by the 3-5 day of the disease.
Treatment of tularemia
Treatment of tularemia is performed exclusively in a hospital setting, with an excretion performed only with complete cure for the disease. Specific therapy is used as a course of antibiotics. Withdrawal of intoxication symptoms is performed with the use of oriented in this direction of therapy in combination with antipyretic and anti-inflammatory medications. In addition, antihistamines and vitamins are prescribed. In some cases, if necessary, drugs are also used to normalize the cardiovascular activity.
Sterile bandages are used for skin ulcers. Festering buboes are opened and drained
If there is a symptomatic symptom that is characteristic of tularemia, it is necessary to consult an infectious disease specialist.