Tularemia is a natural focal acute infectious disease that occurs with fever, septicemia, and a characteristic lesion of the lymph nodes.
Etiology . The causative agent (Bact. Tularense) - an aerobic, 0.2-0.7 microns in size, has the form of a small coccus, it is immovable, it does not form a spore, it is gram-negative, it releases endotoxin. Bacteria can persist for a long time in the external environment, for example in water at t ° 1 ° - up to 9 months. without a decrease in virulence, with an increase in f to 20-25 ° the bacteria die in water for 1-2 months; to low temperatures are insensitive, survive at t ° -30 °. Heating to t ° 60 ° kills bacteria after 20 minutes, boiling immediately. Resistant to drying up to 1.5 months. In salted meats it is viable up to a month. Conventional disinfectants [1-3% lysol, mercury (mercuric chloride) solution 1: 1000, 1% soap-cresol solution, 5% alcohol] and ultraviolet rays quickly kill the pathogen. Chlorine lime in a dose of 1-2 mg per 1 liter of water at t ° 12-16 ° kills germs in contaminated water.The
Epidemiology . The reservoir and source of tularemia in nature are rodents, especially common voles, water rats, house mice, partly muskrats, hamsters, and hares. Ways of infection with tularemia: contact - contact with sick animals and their secretions, with contaminated objects (hay, straw, grain), as well as bathing; aspiration - inhalation of dust in the threshing of stale grains, shaking straw and hay, contaminated with rodent secretions, with the insulation of dugouts, trenches; alimentary - the use of water from sources contaminated by secretions or corpses of sick rodents, eating poorly processed meat of sick animals (rabbits, rabbits); transmissible - with the bites of ectoparasites of rodents (mites, etc.) and flying insects (mosquitoes, horseflies).
There are the following epidemic outbreaks of tularemia. 1. Fishing - arise in the spring when hunting for a water rat among hunters and catchers. Infection occurs by contact with the carcass during the removal and processing of pelts. Clinically, the bubonic forms of tularemia predominate, with the localization of buboes in the upper limbs. 2. Agricultural - recorded in late autumn and winter. Delay in harvesting, belated grain threshing lead to increased multiplication of mouse-shaped rodents in clogged fields, in stacks and stumps of unmilled bread , haystacks and straw. With a massive accumulation of rodents, tularemia almost always produces epidemic episodes with the death of up to 80% of mice. The causative agent from the excreta and corpse of the rodent into water, food , fodder, grain, potatoes and others, as well as the inhalation of dust during the threshing of rodent-filled breads, promote the spread of abdominal and pulmonary forms of tularemia. 3. Water - arise when drinking water from an infected source. Abdominal and anginous-bubonic forms of tularemia predominate. 4. Food - usually shorter than water. Occur when using products contaminated with infectious secretions of rodents. They are distinguished by the appearance of angina, the predominance of cervical, parotid and submandibular buboes, as well as abdominal and generalized forms. 5. Transmissible - arise when biting blood-sucking arthropods (mosquitoes, horns, mites, etc.). At the site of the bite of the transporter appears the sore, then the bubo in the regional lymph node (ulcerative-bubonic form).
From a sick person, healthy tularemia is not transmitted. The patient acquires a permanent immunity.