Tularemia is a natural focal zoonotic infectious disease rodents, some species of domestic animals, birds and humans, caused by the bacterium tularensis. The disease is characterized by intoxication, fever, lymphadenitis and lesions internal organs(spleen, liver and lungs).

Tularemia is observed in humans and animals in many countries that are located in the northern hemisphere, in places where rodents are highly sensitive to the causative agent of tularemia.

Economic damage. In some years, tularemia caused significant losses to sheep and pig farms and fur farms. Economic damage is made up of mortality and reduced productivity animals.

The causative agent of the disease. Tularemia is caused by the small Gram-negative coccobacterium Francisella tularensis. Within this species, three subspecies are clearly distinguished: Nearctic, Central Asian, and Holarctic. The Holarctic subspecies F. tularensis subsp. is distributed in Russia. Holarctctica Ols., Mesh., 1982 (with two biovars I Erys and II EryR), whose circulation is carried out mainly through rodents and lagomorphs, as well as ixodid ticks and through water. The causative agent of tularemia is highly resistant to external environment, especially when low temperatures. V river water at a temperature of 1 ° C, the pathogen persists for up to 9 months, in frozen water (-5 ° C) up to 10.5 months. In winter, in the water of small flowing reservoirs - at least 5 months. In moist soil, at 4 °C, it persists for more than 4 months, and at 23-25 ​​°C - up to 2.5 months. V sour milk and cottage cheese, microbes remain viable for up to 2 days, in frozen milk - up to 104 days, in meat - 93 days; on the skins of water voles, mice and guinea pigs - 26-40 days. Not resistant to high temperatures(at 60°C it dies in 5-10 minutes, at 100°C - within 1-2 minutes), to sunny, ultraviolet rays and disinfectants(solutions of lysol, bleach, chloramine kill the pathogen in 3-5 minutes).

epizootic data. V vivo most susceptible to disease hares, wild rabbits, muskrats, beavers, water rats, hamsters and chipmunks. Of the farm animals, they are the most sensitive and can get sick with clinically pronounced signs diseases of young animals (lambs, piglets, chickens). Turkeys, geese and ducks are resistant to infection with tularemia. Dogs and cats are less susceptible to the causative agent of tularemia.

People are very receptive to tularemia, mainly hunters in the fisheries for the skins of water rats and ground squirrels become infected.

Main source the causative agent of the infection is rodents and sick farm animals, the transmission factors are blood-sucking insects, infected water sources, feed and soil. Infection farm and domestic animals going on primarily alimentary, aerogenic and transmissible ways with bites blood-sucking insects (gadflies, mosquitoes, fleas, ixodid and gamasid ticks). Possible intrauterine transmission pathogen. Dogs from hunters become infected by eating infected carcasses of hares, cats and pigs by eating infected carcasses of rats and mice.

In farm animals, the disease is usually asymptomatic. Sporadic outbreaks of the disease may occur in large cattle, horses, pigs, sheep, reindeer, camels, rabbits, poultry and cats. For outbreaks of tularemia characteristic spring-summer (pasture) and autumn-winter (stall) period, which is associated with increased activity blood-sucking insects and more active migration of rodents to livestock premises, feed storage areas. Natural foci of tularemia remain active for up to 50 years or more.

Pathogenesis. Once in the body with food, water, air, when bitten by blood-sucking insects, the pathogen begins to multiply at the site of introduction. From the place of primary localization with the flow of blood and lymph, it is brought into the regional lymph nodes, where, multiplying, it causes purulent inflammatory process, leading to an increase in the size of regional lymph nodes, hardening, then softening and opening. The tissue surrounding the lymph nodes becomes hyperemic and edematous. Bacteria subsequently from the affected nodes penetrate into the bloodstream and are carried with the bloodstream throughout the body (bacteremia) - the spleen, liver, lungs, etc., causing the formation of new abscesses and damage to parenchyma cells. All this ultimately leads to the development of sepsis and death of the animal.

The course and symptoms of the disease.

An outbreak of tularemia in wild animals can be suspected by increased incidence of rats and mice. Sick hares and squirrels lose their timidity in front of a person, do not flee, make it easy to catch themselves.

Incubation (hidden) period with tularemia in farm animals lasts from 4 to 12 days, and depending on the species, breed and age of the animal, the disease can occur acute, subacute and chronic, appear in typical or atypical(erased, asymptomatic) form.

Sheep, especially lambs, acute during the course, a depressed state is observed (adult sheep and lambs stand with their heads low, and sometimes lie, while they react poorly to external stimuli), while grazing they lag behind the herd, a staggering gait is observed. Breathing is sharply quickened (up to 90 beats per minute), pulse up to 160 beats. in 1 minute. Body temperature rises to 40.5-41°C, lasts for 2-3 days, then drops sharply to normal and rises again by 0.5-0.6 degrees. In sick animals, signs of conjunctivitis and rhinitis join; submandibular and prescapular lymph nodes are enlarged, tight and painful. Affected lambs show relaxation and paresis hind limbs, diarrhea, pallor of visible mucous membranes (due to sharp decline hemoglobin in the blood). The illness lasts 8-15 days. The incidence of tularemia in lambs reaches 10-50%, up to 30% of the diseased die.

At erased form diseases (usually in adult sheep) there is a slight depression, an increase in body temperature by 0.5 degrees. After 2-3 days, the above symptoms disappear and the animal recovers.

piglets the disease is manifested by an increase in body temperature up to 42 ° C, depression, refusal to feed, rapid breathing of the abdominal type, cough. Observed profuse sweating, causing the skin to become dirty and crusty. Lymph nodes are enlarged. The high body temperature lasts 7-10 days, and if pneumonia does not superimpose on the disease, a slow recovery occurs. Most sick piglets become malnourished and die. At cattle tularemia in most cases is asymptomatic, being detected by a serological blood test. Some cows have a short-term fever, mastitis and swollen lymph nodes. In pregnant animals 50 days after infection abortion is possible. Horses tularemia occurs in mild and asymptomatic forms diseases that are established during allergic and serological studies. At foal mares tularemia manifests itself mass abortions at the 4-5th month of pregnancy, without subsequent complications. camels the main clinical sign of tularemia is chills, cough, significant fever, rapid breathing, enlargement of subcutaneous lymph nodes and loss of nutrition. Chickens, pheasants, pigeons get sick more often asymptomatic, in chickens there is a decrease in fatness, an inflammatory process occurs in the region of the root of the tongue, pharynx and occurs accumulation of caseous masses. At rabbits and fur animals rhinitis is noted subcutaneous lymph node abscesses, emaciation. The disease can last from 5-6 days to 1 month or more. Most sick animals die. At river beavers with tularemia, there is a loss of appetite, depression, signs general weakness, decreased response to external stimuli. Goes enlargement of the prescapular lymph nodes. In dogs the disease proceeds with a variety of clinical signs. In dogs, a depressed state is observed (lethargy, animals hide in the shade, lie motionless), appetite is lost, mucopurulent conjunctivitis, severe emaciation. At clinical examination dogs find feature disease- an increase in inguinal, popliteal and mandibular lymph nodes. In dogs, paresis and paralysis of the hind limbs are observed. The disease may be accompanied by gastroenteritis. By the end of the disease, the dog has a sharp weakness, a decline in cardiac activity, as well as anemia. In cats observed laxity and swelling of the lymph nodes of the head and neck, vomiting, emaciation and death.

pathological changes. The corpses of dead animals are depleted. The skin in the axillary region is ulcerated and necrotic. On the inside skin and subcutaneous tissue compacted foci the size of a pea with hemorrhages. Enlarged tonsils, cervical, pharyngeal, prescapular lymph nodes, there are often purulent inflammation . In lambs and piglets - fibrinous pleurisy and focal serous-fibrinous pneumonia, congestive hyperemia and necrotic foci in the liver. Pinpoint hemorrhages on the epicardium and adrenal glands.

In chickens, in most cases, in addition to exhaustion, they find an increase and hyperemia of the spleen and liver, in quails, in addition, small necrotic foci in the liver.

Lesions in rodents are similar to pathological changes observed in pseudotuberculosis.

Diagnosis.

The diagnosis is made on the basis of an analysis of epizootological, clinical, pathoanatomical data, taking into account the results of bacteriological, serological (RA, RP, RIGA, RN) and allergic (intradermal administration of tularin) studies. A veterinarian should suspect tularemia when mass mortality of rodents.

For bacteriological examination, the whole corpses of rodents and small animals are sent to the veterinary laboratory; from the corpses of large animals, the liver, kidneys, heart, affected lymph nodes are sent for examination.

differential diagnosis. Need to exclude, and (by conducting bacteriological, serological and allergic studies).

Immunity, specific prophylaxis. As a result of being ill with tularemia, animals produce tense immunity. In recovered animals, antibodies to tularemia and sensitization occurs organism. To date, proposed for human immunization against tularemia live vaccine when vaccinated animals turned out to be weakly immunogenic, as a result Animals are not vaccinated against tularemia.

Prevention and control measures.

In the system of preventive measures, the main place is given to measures to neutralize the source of the infectious agent, transmission factors and carriers of the pathogen.

In enzootic natural foci of tularemia, it is necessary to constantly monitor the reproduction of mouse-like rodents; in the anthropourgical focus, the veterinary service, together with the bodies of Rospotrebnadzor, should conduct comprehensive work for the extermination of rodents: in residential premises locality, in granaries, in food and feed blocks, in livestock buildings, etc.

corpses farm animals and rodents, those who died from tularemia are destroyed in biothermal wells.

Disinfection bulky feed infected with the causative agent of tularemia occurs at different times, depending on the ambient temperature: at 8-14 ° C - after 60 days, at 15-20 ° C - after 40 days, at 20-25 ° C - after 35 days (preliminary carcasses of rodents are removed from feed). Food and feed grains are disinfected heat treatment in grain drying units at a temperature of 70 ° C for 10 minutes. For a full guarantee, the grain processing time must be extended to 30 minutes. The seed grain is sprayed formalin solution at a concentration of 1:90 or 1:150, with a two-hour exposure under a tarpaulin and then during the day in the open air.

Reducing the number of rodents in agricultural enterprises is achieved by pressing hay and straw into bales; high-quality processing of haystacks and straw swathes with ammonia, transportation of roughage after harvesting to well-equipped storage facilities. It is not recommended to leave haystacks and straw along the edges of ravines or forest edges.

The decrease in the number of ixodid ticks is facilitated by the late start of grazing in spring, the reduction in the area of ​​natural meadows, the grazing of livestock on artificial and cultivated pastures, and the processing of ticked livestock.

Managers of agricultural enterprises and specialists should take measures to prevent infection of livestock workers. The export of animals from disadvantaged farms is allowed after the examination of blood serum in the Republic of Armenia and the treatment of livestock against pasture ticks.

Measures to reduce the loim potential of natural foci of tularemia.

Characteristics of natural foci tularemia.

Active natural foci should be considered those in which cases of human disease are recorded, cultures of the causative agent of tularemia are isolated from rodents, arthropods; objects of the environment or tularemia antigen is regularly detected in the pellets of birds or litters of predatory mammals.

Inactive are foci where tularemia is not recorded in humans, but rare finds of the pathogen or tularemia antigen are found in environmental objects.

Tactics of epizootic examination of natural foci of tularemia.

All mammals in relation to tularemia are divided into 3 groups:

1) highly susceptible and highly sensitive mammals (rodents, lagomorphs and insectivores);

2) highly susceptible but insensitive mammals (field mice, all kinds of rats and ground squirrels, squirrels, chipmunks, hedgehogs, beavers and other mammals);

3) insensitive and practically insensitive mammals (most carnivores and farm animals).

During the epizootological examination of the focus, it is necessary first of all to examine the mammals of the 1st group, then the 2nd and 3rd groups. Arthropods include ixodid ticks, lice, fleas, gamasid and red mites, and blood-sucking Diptera.

Analysis of the results of the epizootic survey and forecasting of the epizootic situation for tularemia.

Information about the distribution, dynamics of the number of background species of mammals and blood-sucking arthropods, isolation of pathogen cultures or findings of tularemia antigen in environmental objects is mapped and analyzed. It is necessary to inform the territorial centers of Rospotrebnadzor about all newly identified natural foci of tularemia.

Measures to neutralize the source of the infectious agent, transmission factors and carriers of the pathogen.

Events are held on two main directions:

• elimination of conditions for human infection (general sanitary and hygiene measures, including sanitary and educational work);
• decrease in the loimopotential of natural foci (measures to destroy carriers and carriers of the infectious agent).

General sanitary measures have their own characteristics different types morbidity. In case of transmissible infections through blood-sucking Diptera, repellents, protective clothing are used, and the access of the unvaccinated population to unfavorable territories is restricted, in special occasions carry out disinfection of reservoirs.

For prevention of commercial infections carry out a complex of sanitary and anti-epidemic measures in the places of hunting of animals and in warehouses for storing skins.

With water flashes stop bathing and water use from an infected reservoir, it is necessary to use only boiled water for drinking, and if well water is contaminated, they take measures to clean the well from the corpses of rodents and disinfect the water. In order to avoid infection during winter field work in natural foci, it is unacceptable to involve unvaccinated people in the work. Disinfection of grain and roughage is carried out.

At household infections provide rodent impermeability of residential and utility rooms, deratization and wet cleaning with the use of disinfectants.

At industrial and food contamination carry out sanitary and anti-epidemic measures at enterprises or warehouses, including the disinfection of infected raw materials and products thermally. At meat processing plants destroy ixodid ticks on livestock received for processing.

On the hunt it is necessary to disinfect hands after skinning and gutting hares, muskrats, moles and water rats.

Treatment. specific means There is no cure for tularemia in animals. Sick animals are given courses of antibiotic therapy ( streptomycin, chloramphenicol, oletethrin, tetracycline, chlortetracycline, dihydrostreptomycin), use sulfanilamide and nitrofuran preparations according to the instructions for their use.

epizootology

125 species of vertebrates and 101 species of invertebrates are susceptible to tularemia. Under natural conditions, tularemia mainly affects hares, wild rabbits, mice, water rats, muskrats, beavers, hamsters, and chipmunks. Cases of diseases of birds of various species were noted. Natural foci can be active for 50 years or more. Of the farm animals, lambs and piglets under the age of 2-4 months, cattle, horses and donkeys are the most sensitive to the causative agent of tularemia and can become ill with clinically pronounced signs of the disease. Buffaloes, camels, reindeer and rabbits are also susceptible to infection. Mature sheep are more resistant than young ones, and goats are more resistant than sheep. Of poultry, chickens (especially chickens) are the most susceptible. Turkeys, ducks and geese show high resistance to infection. Dogs and cats are less susceptible to the pathogen. Most susceptible laboratory animals Guinea pigs and white mice.

The main source of the pathogen is sick animals. Reservoir it in environment are the populations of the above species of wild animals, and the transmission factors are blood-sucking insects, infected water sources, feed and soil.

Infection of agricultural and domestic animals when they are included in the epizootic process occurring among wild animals occurs mainly by alimentary, aerogenic and transmissible routes. Bacteria can enter the body even through intact skin, conjunctiva and mucous membranes of the respiratory system. Intrauterine transmission of the pathogen is possible. Dogs usually become infected by eating infected carcasses of hares and rabbits (objects of hunting), and cats, like pigs, by eating the corpses of rats and mice.

Due to the predominantly latent (asymptomatic) manifestation of the disease, slight contamination of organs, and the absence of active bacterial excretion, farm animals do not participate in the circulation of the pathogen, therefore, there is no mutual re-infection within the herd.

Outbreaks of tularemia are observed both in the spring-summer (pasture) and autumn-winter (stall) period, which is associated, respectively, with increased activity of blood-sucking insects and more intensive migration of rodents to livestock buildings, food storage areas in certain seasons of the year.

Pathogenesis

Once in the body of an animal with food, water, air, or when bitten by blood-sucking arthropods and rodents, the pathogen begins to multiply at the site of introduction. Then, along the lymphatic pathways, it enters the regional lymph nodes, where, continuing to multiply, it causes a purulent-inflammatory process. This process is accompanied by a significant increase in the size of the lymph nodes, their hardening, and then softening and opening. Surrounding tissue hyperemic and edematous. From the affected nodes, microbes quickly penetrate into the bloodstream and with the bloodstream (bacteremia) spread throughout the body, settling in other lymph nodes, spleen, liver, lungs, etc., causing the formation of new pustules and damage to parenchyma cells (septicemia develops ). The death of animals occurs from intoxication, when the concentration of bacteria in the blood reaches the terminal phase.

Tularemia- a contagious disease of rodents (hares, rabbits, ground squirrels, water rats), some species of domestic animals and birds, as well as humans, caused by a specific pathogen - b. tularense. The disease is septicemic in nature or proceeds more slowly, with swelling and cheesy degeneration of the lymph nodes, enlargement of the spleen and the formation of inflammatory-necrotic nodules in the liver, spleen and lungs.

Historical review. In 1911, in the province of Tulare (California), a microbe culture was first isolated from fallen squirrels; he was given the name b. tularense.

After 10 years, many diseases were identified with tularemia, which different authors gave various titles("rabbit fever", etc.); the clinic of tularemia in humans was described and the source of human infection was proven.

Subsequent studies established the tularemia etiology of the so-called tick paralysis of sheep (“tick paralysis”), which caused mass mortality.

Prevalence. In the United States, the disease has been reported in humans and rodents in 44 states. A significant prevalence of sheep tularemia has been observed in Mop-tano State. Tularemia is also established in Canada, British Columbia, on about. Java, in Japan, USSR, Norway, Sweden, Finland, Italy, Turkey, Tunisia, Austria, Czechoslovakia, Alaska.

Etiology. The causative agent of tularemia is an immobile, gram-negative, non-spore-forming, non-liquefying gelatin, aerobic, highly polymorphic bacillus with a delicate kathsula. In smears from cultures grown on solid media, it looks like a coccus or coccobacteria; on liquid media, microorganisms are bipolar, curved, sometimes forming filaments, with rounded ends. The microbe stains well, but only with prolonged exposure, with Giemsa stain and Ziehl carbolic fuchsin. The size of the microbe - 0.2x0.3 - 0.7 (A. characteristic feature it is considered the ability to pass through the pores of filters in the form of flakes), in ascites agar with glucose, 10% blood agar, on clotted Loeffler serum, semi-liquid agar. Addition to Wednesdays parenchymal organs(liver, spleen) improves crop growth. Colonies on McCoy and Chapin medium (60 parts egg yolk and 40 parts physiological saline; coagulation at 80°C for 30 minutes) have the appearance of mucous droplets, soft-grained, moist, shiny. On this medium, growth appears after 2 to 7 days, sometimes even on the 34th day after sowing.

On Francis's medium (cystine-glucose agar), colonies bigger size than on the yolk medium, milky white, moist, confluent. In the practice of mass bacteriological research cases of growth of the activator on a usual agar and bulsshe are established. The pathogen decomposes sugars to form acids (glucose, glycerin, mannitol, levulose, maltose).

On media containing cystine, hydrogen sulfide is formed. The cultures release a toxin that is deadly to guinea pigs. Optimum temperature 37°C; the microbe is very sensitive to slight fluctuations in temperature.

Sustainability. The causative agent of tularemia is quite resistant. It remains in water for up to 88 days, on the skins of water rats, mice and guinea pigs - for 35 - 45 days, in the organs of birds (chickens, sparrows, gray crows) - 25 - 40 days, in larvae and nymphs of ticks - up to 240 days. Horseflies transmit the infection for 2 days after sucking blood. In mosquitoes, the pathogen persists and is transmitted for 23 to 50 days. The organs of sick rabbits (liver and spleen) are contagious for 3-8 days, and the muscles - up to 35 days.

On the line sunshine the pathogen dies in 30 minutes, on scattered - in 3 days. Heating the culture to 56 - 58° kills it in 30 minutes; heating up to 60 ° - in 5 minutes; 0.1% formalin kills b. tularense within 24 hours, tricresol 0.1% in 30 minutes, 0.5% in 2 minutes; 50% alcohol - in 5 minutes.

Susceptibility of various animal species. Tularemia, as a spontaneous infection, is observed mainly in animals from the rodent order. Carriers of infection in the territory of the USSR include water rats, ground squirrels and mouse-like rodents. In addition, gray rats, muskrat, hamster, marmot, opossum, jerboas, woodland and domestic mouse, gerbils, baby mice and their predators - weasels, ferrets, moles.

A natural infection, which has the character of an epizootic, has been noted in wild rabbits and hares, as well as in sheep. Goats appear to be less susceptible to infection than sheep, as immunization with virulent cultures did not cause any symptoms of the disease, while sheep died on days 23 and 31 after virus injection. In places where the disease affects mouse-like rodents, massive disease cases, and case of cats. Isolated cases of tularemia have been observed in piglets, dogs, foxes and wolves. Camels, donkeys and pigs are susceptible to experimental infection, but the disease is not fatal. Cattle and horses in areas infected with tularemia react serologically to this infection.

People are very receptive; they become infected mainly in fisheries for the skins of water rats and ground squirrels. Monkeys under experimental infection fall ill with tularemia.

Of the birds, as susceptible, domestic chickens, blue partridge, quails, sparrows, crows, magpies are noted.

Of the laboratory animals, guinea pigs and white mice are the most sensitive, and less so are rabbits and white rats.

Inoculation of this disease by ticks in sheep and small animals has been proven experimentally and in vivo. Ticks transmit the infection transovarially (through the egg). Peddlers of infection are also horseflies, mosquitoes, autumn flies, mouse lice, and fleas.

Infection of people occurs when drinking water from infected streams, wells, springs. Some water sources, including springs, contained the virus for a long time (3-5 months). Infection water sources intensive epizootics of tularemia among mouse-like and water rats contribute.

The possibility of infection of domestic animals on pastures and when eating roughage inhabited by sick rodents is not ruled out. There have been cases of people falling ill during agricultural work (sorting straw, transporting and cutting it, sorting and drying grain).

Observations and experimental studies showed that the transfer of z-arase is also possible in other ways - dermal, conjunctival, subcutaneous, intraperitoneal.

Pathogenesis. Tularemia is a typical bacteremia affecting vascular system, without selective localization in organs, but with predominant lesion lungs, spleen and lymph nodes. When infected by direct contact with infected material or through an insect bite, the infection is first localized at the site of the "entrance gate"; at the same time, the pathogen enters the lymph nodes and into the blood. Later b. tularense - not found in the blood; this coincides with the beginning of granulation of the formed sore. The cause of death in tularemia is septicemia caused by the appearance of a (secondary) pathogen in the blood stream.

Tularemia- natural focal infectious disease of animals and humans. It is characterized by fever, diarrhea, emaciation, swollen lymph nodes, as well as black phenomena and abortions in animals, in humans - fever, damage to the respiratory tract, lymph nodes, and external integuments.

The causative agent of the disease is a very small microbe, often coccoid with thin capsule. Motionless, does not form a dispute. Contains antigens associated with its pathogenicity. The causative agent of tularemia belongs to the family of brucellosis bacteria of the genus Francisella.

The microbe is not resistant to high temperatures (at 60 "C it dies in 5 - 10 minutes, at 100 C - within 1 - 2 minutes), but at a temperature of 0 - 4 "C in water and soil it remains from 4 to 9 months, in grain and fodder at 0 "C survives up to 6 months, at 8 - 12" C - up to 2 months; at 20 - 30 "C - up to 3 weeks; in the skins of rodents that have died from tularemia at 8 "C, it remains viable for up to 1 month, at 30 "C - up to 1 week. The microbe is not very resistant to drying, ultraviolet rays, disinfectants: solutions of lysol, chloramine, bleach kill it in 3-5 minutes.

ANIMAL TULAREMIA

The history of the discovery and study of tularemia is of particular interest. For the first time, tularemia was established in 1911 in California, in the area of ​​Tulare, in wild rodents. In the USSR in 1926, he isolated a culture of the tularemia pathogen from water voles, in agricultural and game animals - in 1927. Currently, the disease has been registered throughout North America, partly Central and on the Eurasian continent. More often it is recorded in the valleys major rivers in places of distribution of the water rat, as well as in the steppe regions during the years of active reproduction of rodents. In principle, numerous species of rodents, insectivores, predators are the reservoir of the pathogen, but the main species that ensure the existence of tularemia bacteria in nature are common voles, water rats, muskrats, hares, hamsters, from which domestic rodents become infected. Many types of ticks (especially ixodid), mosquitoes, horseflies are also a reservoir of the pathogen.

Farm animals are insensitive to tularemia. They become infected from sick rodents in natural foci of this disease. Tularemia is more often hidden in them, accompanied by a slight contamination of tissues with bacteria, microbes are usually not found in the blood and secretions, in connection with this, farm animals do not participate in the natural cycle of the microbe in the foci of the disease.

TULAREMIA HUMAN

A person is more likely to become infected from the bites of infected ticks, mosquitoes, horseflies; infection is possible as a result of penetration of the pathogen through skin injuries due to the bite of infected rodents, when skinning, butchering carcasses, etc.; infection is possible through water and food contaminated with rodent secretions, as well as by airborne dust, that is, by inhalation of dust contaminated by the pathogen.

The natural susceptibility of people is very high. Past illness usually forms lifelong immunity.

An increase in the incidence of people is observed in the years of an increase in the number of rodents. There are sporadic cases and epidemic outbreaks, which are usually characterized by the predominance of any one of the routes of transmission of the pathogen. Mostly rural residents get sick, becoming infected in domestic (usually when drinking water or products contaminated with the pathogen) or industrial (occupational infection when threshing grain contaminated with rodents, processing vegetables, transporting straw) conditions, as well as hunting, fishing, where there is a risk of transmissible infection . Laboratory infections with tularemia are also known.

The incubation period lasts from 1 day to 3 weeks, usually 3 to 7 days.

Main Clinical signs: acute onset. The body temperature rises to 38 - 39 "C and then persists for 2 - 3 weeks. There are chills, a sharp headache, muscle pain, sometimes nausea and vomiting. The face and conjunctiva become red. The liver and spleen are enlarged. Clinical form diseases are largely determined by the transmission of the pathogen, that is, its entrance gate: transmissible and contact infection are accompanied by the development of bubonic (an increase in various lymph nodes) or ulcerative-bubonic form; water and food way lead to anginal-bubonic or intestinal (abdominal) form; aspiration infection entails the development of a pulmonary form with damage to the bronchi or lungs. This option is long and severe course. With massive infection, as well as in weakened individuals, a primary septic, or generalized, form is possible.

Preventive measures: the fight against rodents, their destruction in warehouses, barns, dwellings, protection of warehouses and livestock premises from the penetration of rodents.

Scheduled vaccination of the population of territories enzootic for tularemia is carried out with a dry live tularemia vaccine. As a result, the immune layer should be at least 90%. Vaccination is carried out once by the skin method on the outer surface of the middle third of the shoulder. The result is checked on the 5th - 7th day after vaccination, and in the absence of a Y reaction - on the 12th - 15th day. Revaccination is carried out according to epidemiological indications 5 years after vaccination.

Pathogen: Francisella tularensis discovered in 1912. McCoy and S. Chepin in the Tulare area. Tularemia bacteria are very small, coccoid and rod-shaped, immobile, non-spore-forming cells, G~. Bacteria are characterized by polymorphism. They can be in the form of weights, cocci of very small sizes; aerobe, does not grow on conventional nutrient media, develops well at 37°C in media rich in vitamins, for example, in the yolk medium.

The pathogen remains viable in water for 3 months, in meat for 93 days, in milk for 104 days. The sun's rays kill in 30 minutes, heating at 60 ° C - in 5-10 minutes.

Epizootology. Course and symptoms. It affects mainly rodents. A person is very sensitive to tularemia. Agricultural animals are not very sensitive to the causative agent of tularemia, they become infected in natural foci. Sporadic cases have been reported in sheep, cattle, horses, pigs, reindeer, camels, cats, poultry.

The young are more susceptible. Infection occurs alimentary, airborne and as a result of bites of arthropod insects - ticks, fleas, mosquitoes, horseflies. Transmissive way infection determines the spring-summer-autumn seasonality of the disease; the preservation of the pathogen in the external environment contributes to the long-term carriage of bacteria various types mammals and arthropods.

Incubation period: 4-12 days. In cattle, swollen lymph nodes, mastitis, abortion, in some cases, can occur in the form of paralysis with a fatal outcome. In pigs, camels, buffaloes, there is a loss of appetite, chills, coughing, rapid breathing, an increase in subcutaneous lymph nodes, and sweating in piglets. In lambs, depression, fever, increased heart rate and respiration, pallor of the mucous membranes, and then paresis and stiffness of the muscles of the limbs are noted. In horses, along with a clinically pronounced form (abortion for 4-5 months), a mild and asymptomatic course is observed, which is detected by an agglutination reaction.

Pathological and anatomical changes. Sheep slaughtered in acute stage diseases, find changes on the inside of the skin in places of tick bites, translucent areas the size of a pea appear there, sometimes with a slight hemorrhage and tissue thickening, skin ulcerations and necrotic areas are also observed, especially in the axillary region. Subcutaneous tissue hyperemic, nodules are noted in it, often undergoing decay. At chronic form sheep diseases are exhausted. There are nodules such as infectious granulomas in the lungs, liver, spleen, serofibrinous pleurisy or pneumonia without pleurisy, a strong venous congestion with injection of vessels on the inside of the skin, as well as in the lungs, liver, spleen and intestines. The heart is filled with dark, weakly clotted blood, the heart muscle is flabby, petechial hemorrhages are frequent under the epicardium. In pigs, mainly in piglets, signs of pleuropneumonia are found, in some cases purulent processes in the submandibular and parotid lymph nodes.

Diagnostics. A punctate is sent to the laboratory from enlarged lymph nodes, from an aborted fetus or the whole fetus, urine, feces. After death - the liver, kidneys, spleen, enlarged lymph nodes from large animals, the corpses of rodents.

Smear microscopy, bacteriological and serological testing, allergic diagnostics, bioassay.

Differential diagnosis. In sheep, tularemia should be differentiated from listeriosis and other diseases associated with paralysis of the limbs and coma, in piglets - from hemorrhagic septicemia.

Prevention and treatment. Treatment: prescribe antibiotics (gentamicin, tetracycline), a vaccine from killed tularemia bacteria.

Prevention: consists in carrying out general anti-epidemic measures in outbreaks and immunizing people. Specific prophylaxis carried out with a live Gaisky Elbert vaccine, as well as inactivated vaccine prepared from a protective antigen. The vaccine is available in dry form. Apply on the skin once. The duration of post-vaccination immunity is 3-6 years.

Veterinary and sanitary examination. Sick animals are not allowed to be slaughtered. In case of slaughter, all products must be destroyed. Products that have come into contact with carcasses, organs or blood of animals with tularemia are boiled. The premises where carcasses or organs from sick animals were located are disinfected with a hot 2% sodium hydroxide solution. The working tool is boiled in a 5% solution of soda ash for 30 minutes. Contaminated gowns and other overalls are sterilized in autoclaves at 1.5 atm - 20 minutes.