Tularemia( epidemic lymphadenitis) - Causes, symptoms and treatment. MF.

Tularemia( plague disease, rabbit fever, small plague, fever fever, mouse disease, epidemic lymphadenitis) is an acute zooanthrapanous natural focal bacterial infection, with multiple transmission mechanisms characterized by febrile-intoxication syndrome, inflammatory changes in the entrance gates of infection andregional lymphadenitis.

For the first time the disease was established in 1911 in California, when McCoy and Chepy, discovered a plague-like disease in gophers, isolated the pathogen and named it Bacterium tularense( at the site of the epizootic in the area of ​​Lake Tulare).Later, the susceptibility of this disease was found in humans, and after a while they learned about the extent of prevalence: throughout the whole of North and Central America, on the Eurasian continent. In general, it is believed that the disease is there, where rodents actively multiply.

Tularemia causative agent

Francisella tularensis is a gram-negative rod( ie, it is pink) and this color indicates the presence of a capsule, hence some phagocytic protection when ingested into a macroorganism. The dispute and flagella does not. There are also other features of the structure of the pathogen that create the features of the symptoms:

• neurominidase promotes adhesion( attachment) to damaging tissues;
• endotoxin causes febrile-intoxication syndrome and allergenic properties of the cell wall;
• the ability to multiply in phagocytes and suppress their killer effect;
• The presence of receptors for Fc-fragments of immunoglobulin class G( IgG), hence the activity of complement and macrophage systems is disrupted.

The last two factors lead to an allergic reorganization of the immune system

. The causative agent is relatively stable in the external environment( despite the absence of sporulation), especially at low temperature and high humidity: survives at -300 ° C, in ice - up to 10 months, infrozen meat for up to 3 months, in water for more than a month( at 10 ° C for 9 months), in isolations from rodents for more than 4 months, in soil for 2.5 months, in milk for 8 days, at 20-30 ° C - up to 3 weeks.

The causative agent is sensitive to the following factors:

• high temperature - at 60 ° C perishes within 10 minutes;
• direct UVI - perishes in 30 minutes;
• Ionizing radiation and disinfectants( 3% lysol, 50% alcohol, formalin, chloramine, chloric lime, and mercuric chloride) are detrimental to action - the inactivation of the pathogen occurs after 10 minutes.

The susceptibility of people to tularemia is high and reaches 100%, that is, each contact with the pathogen will become ill, without sexual and age restrictions. Summer-autumn seasonality is noted. Natural foci prevalence - natural foci of tularemia exist on all continents of the northern hemisphere, in the countries of Western and Eastern Europe, Asia and North America. On the territory of the Russian Federation, the disease is registered everywhere, but mainly in the North, Central and West Siberian regions of Russia.

The causes of infection with tularemia

The source is about 150 species of vertebrates( 105 mammals, 25 bird species, some hydrobionts), but the honorable place is occupied by a detachment of rodents( vole, water rat, house mouse, rabbits), in the wrong place - livestock( sheep, pigs and cattle).

The carrier is blood-sucking insects( iksodovye and gamasovye mites, mosquitoes, horseflies).Mechanisms of transmission of infection: contact( with direct contact with infected animals or their biological materials), contact-household( when contaminated with waste of sick animals of household items), alimentary( with the use of contaminated food), transmissible( with a bite of infected bloodsucking), aerogenicinhalation of infected dust).

In the human body, the pathogen enters through microtraumas of the skin, intact mucous membranes of the tonsils / oropharynx / gastrointestinal tract / respiratory tract / eye and possibly genital organs. Moreover, for infection, only the minimal infecting dose is needed and, with this disease, this dose is one microbial cell( while in other infectious diseases - 10'⁵ or more)!

Symptoms of tularemia

The incubation period( the time from the onset of the introduction of the pathogen to the onset of symptoms) is 2-8 days, but it may take up to 3 weeks. During this period, the pathogen is fixed and multiplied at the entrance gate and, as soon as the amount of the pathogen reaches a certain concentration, a period of clinical manifestations occurs.

The period of clinical manifestations is characterized by both local and general symptoms. Local changes - inflammatory necrotic reaction at the site of the pathogen, with the formation of the primary affect( skin ulcer, passing the papule, vesicles and pustules, if the primary contact occurred on the tonsils - necrotic tonsillitis, in the lungs - focal necrotic pneumonia, conjunctiva in the conjunctiva).

But local reactions proceed and develop in parallel with the general, namely, regardless of the form of the disease( anginal, abdominal or pulmonary), note the acute onset of the disease( similar to the prodromal period, lasting 2-3 days) - with a febrile-intoxication syndrome( the temperature rises to 38-40 ° C and above, headache, dizziness, general weakness, increased sweating, decreased appetite, bradycardia, hypotension).

General toxification symptoms are explained by the fact that some of the pathogens remain in the gateway of the infection and form the primary focus, and some spread along the lymphogenous and hematogenous pathways. After fixing, the pathogen penetrates into the lymphatic vessels and reaches the regional lymph nodes, where it multiplies unhindered and thus the edema forms in the lymphoid tissue and "bubo" is formed( as in the case of the plague), after which the pathogen enters the blood and causes bacteremia, the blood current is transmitted toorgans and tissues, as a result of which granulomas and necrotic ulcers form in them, various symptoms are formed.

But the variability of clinical forms depends mainly not on the affected organs, but on the location of the entrance gates, according to which the following clinical forms of tularemia are distinguished:

• ulcerative-glandular( bubonic),
• glandular( conjunctivitis);
• anginal-glandular;
• abdominal;
• pulmonary.

After the onset of bacteremia and infection of the organs, a peak period begins, characterized not only by a febrile-intoxication syndrome( the duration of high temperature lasts up to a month!), But also by various other symptoms with the same frequency of occurrence:

- the appearance of the patients is very characteristic: puffy and hyperemicface, possibly with a cyanotic shade around the eyes / lips / earlobes of the ears, around the chin - a pale triangle, the injection of vessels of the sclera, pinpoint hemorrhages on the mucosathroat, erythematous / or papular / or petechial hemorrhages leaving after peeling and pigmentation

- lymphadenitis of different localization. When a bubo occurs( a very large lymph node with a walnut up to 10 cm in diameter), it is said about the BUBBON FORM that arises from the transmissive mechanisms of infection, the localization is more often - the femoral, inguinal, ulnar, axillary. And around this lymph node a conglomerate with signs is formedperiadenitis. There is a bubo on the 2-3 day from the beginning of clinical manifestations and reaches its dawn by 5-7 days, with a gradual increase in local changes: first the skin over the lymph node is not changed, but with the passage of time redness appears + the adhesion of this lymph node to the skin and surrounding tissues+ soreness increases. The outcome of this bubo can be different - from unconscious dissolution, to suppuration with fluctuations and subsequent scarring( in this case, the bubo is filled with plum pus, which dissolves and heals for several months, leaving a scar behind).

Bubon with tularemia

- with ulcers, also lymphadenitis is observed, but already with skin changes in the gates of infection that come to the fore - the primary affect is formed at the site of implantation, which passes the stages from the spot - papules - pustules - painless small ulcer(5-7mm) with pitted edges and a scarred serous-purulent discharge and heals this ulcer for 2-3 weeks, leaving a scar behind. This form arises both in the case of transmissible and with contact / contact-household transmission mechanisms. Ordinary localization - open parts of the body( neck, forearm, shin).

- with an angina-tubon form, lymphadenitis becomes the second place, and angina comes to the fore with some peculiarities: hyperemia of the tonsils with a cyanotic shade and swelling, a grayish-white island or filmy plaque is heavily removed and therefore it can be confused with diphtheria films,but unlike the latter, the films with tularemia do not go beyond the tonsils. In a few days, under these deposits slowly healing ulcers are formed( in rare cases, even before the film).The given form arises at alimentary infection, to this form can join further and the abdominal form.

- ABDOMINAL FORM( gastrointestinal) is the rarest, but the heaviest form. The clinic is very variable: cramping or aching pains, spilled or localized, the tongue is covered with a greyish-white coating and dryish, dyspeptic phenomena( constipation and dilution of the stool are possible).

- GLAZOBUBONNAYA FORM occurs when the pathogen enters the conjunctiva through contaminated hands, with high seedingair - i.e. air-dust path. With this form, conjunctivitis occurs( more often, one-sided), with severe lacrimation and edema of the eyelids, pronounced swelling of the transitional fold, muco-purulent discharge, the presence of yellowish-white nodules on the mucosa of the lower eyelid. In this case, regional lymph nodes increase - bovine, submandibular, anteroposterior.

- PULMONARY FORM( THORACIC) occurs when infected by airborne droplets and can occur either in bronchial or pneumonic form. At a bronchial form - a dry cough, pains behind a breast bone, rigid breath and dry wheezes. This form is easier than pneumonic and clinical recovery occurs in 2 weeks on average.

Diagnosis of tularemia

Diagnosis is based on epidemic, clinical and laboratory data. In epidemiological studies, the relationship and time frame between the clinic and recent departures is established. Because of the vastness and stiffness of the symptoms, the clinical data are of little informative.

Laboratory data are represented by a wide spectrum:

- UAC: normocytrs or leukocytosis( ↑ Lc), neurocytosis( ↑ NF), ↑ ESR.In the midst of a swell - ↓ Lc, ↑ Lf and M. With suppuration of buboes - neutrophilic leukocytosis.

- Serological methods: RA( agglutination test) and RPGA( hemagglutination test) - determination of antibody titers and antigens 1: 100 and, the earliest method - RPGA, and RA allows detecting the growth of antibody titer from 10-15 days,week and, if the titre is not changed or they are not found at all, re-conduct the study after another week and, the increase in antibody titer in 2-4 times make the diagnosis of tularemia eligible. ELISA( immunoenzymatic analysis) is 20 times more sensitive than all other serological methods, but it is advisable to use it from 6 days and points out this method for the detection of specific antibodies - IgG and M, by which the stage of the disease is determined: so, in the presence of IgM, an acute processor the stage of swelling, and the presence of IgG - speaks of later terms from the time of infection and indicates a good immune response.

- Allergological method - the use of a skin allergic test, which is characterized by strict specificity and is carried out from 3 days of the disease, therefore, and refer it to early diagnostic methods. It is carried out as a Mantoux test, but instead of tuberculin, a tular is injected into the middle part of the forearm and the result is evaluated at the end of the first day, the second and third, measuring the diameter of the infiltrate: if the diameter of the infiltrate is more than 0.5 cm, the test is positive if the hyperemia disappears at the end of the first dayis negative. If there are contraindications to the setting of a skin test, an allergological method is also performed, but in vitro( ie in vitro and look at the reaction of leukocytolysis).

- The bacteriological method is aimed at detecting the pathogen in biological substrates, but it can only be carried out in specially equipped laboratories, because the causative agent is highly contagious( infectious), so this analysis is rarely prescribed to patients.

- PCR( polymerase chain reaction) - a genetic method aimed at detecting the pathogen DNA, is informative already in the febrile period, therefore it is also referred to as an allergological method as early diagnostic ones.

Treatment of tularemia

Treatment begins already with the observance of the wardship regime, in which the windows are closed with a mesh to prevent the transmissive transmission mechanism + the strict observance and control of sanitary and hygienic rules( current disinfection using 5% phenol solution, solution of the mercury and other disinfectants).

• Etiotropic therapy is aimed at destroying the pathogen by using antibiotics aminoglycoside and tetracycline. If there is an allergy to aminoglycosides, then as an alternative use cephalosporins of the third generation, rifampicin, chloramphenicol, fluoroquinolones, used in age-related doses. Streptomycin - in the national leadership of infectious diseases write about the applicability of tularemia, but try to resort to it rarely and only in a hospital environment, because it blocks neuromuscular conduction with the subsequent arrest of breathing. Gentamycin - 3-5 mg / kg / day for 1-2 doses, Amikacin - 10-15 mg / kg / day in 2-3 doses. Tetracyclines are prescribed for bubonic and ulcerative-bubonic form;Do not prescribe them to children under 8 years old, pregnant, patients with decompensation from the kidneys and liver. The course of antibiotics 10-14 days.

• Local therapy - for skin ulcers and buboes, is the use of antiseptic dressings, quartz, blue light and laser irradiation. With suppuration of bubo-surgical intervention, which consists in opening the bubo with a wide incision to empty it from pus.

• Patonetic therapy consists in prescribing detoxification, antihistamines, anti-inflammatory drugs, vitamin complexes and cardiac glycosides - according to indications. Also, one should remember about the prevention of dysbacteriosis in the use of antibiotics - prescribe prebiotics and, not only orally, but also rectally, because when passing through the gastrointestinal tract, the bifidum and lactobacillus perish in the acidic environment of the stomach.

Complications of tularemia

• On the part of the immune system - allergic reactions, IDS( immunodeficiency states);But there are no specific target organs, so there is no specific clinic, hence there are no specific complications, but there are the most common( possibly because of the infection gate): ITH( infectious-toxic shock), meningitis, pericarditis, myocardial dystrophy,polyarthritis, peritonitis, corneal perforation, bronchiectasis, abscesses and gangrene of the lungs.

Prevention of tularemia

Prophylaxis is divided into specific and non-specific. Specific - the use of live dry tularemia vaccine, children older than 7 years, staying on endemic in tularemia territories, assess the immunity status for serological tests on 5( 7) and 12( 15) day, 5 years, and 1 time in 2 years, withnegative indicators are conducted by revaccination.

Nonspecific prevention consists in controlling natural foci, timely detection of outbreaks among wild animals, carrying out deratization and disinsection.

With a water flash - forbid to swim in this water and drink unboiled water. Apply specialized clothing when in contact with sick animals or when in their habitat.

Doctor's consultation:

Question: Is it necessary to open the vesicle at the site of the bite?
Answer: no.

Question: Is immunity remaining after the disease?
yes, it is persistent, durable, lifelong;Has a cellular nature( due to T-lymphocytes, macrophages and antibodies), phagocytosis in immunized has a completed character, in contrast to the infected.

Doctor therapist Shabanova IE