Tularemia - what is it? Infectious diseases. Prevention, treatment
Acute infectious natural focal disease, which is characterized by fever, damage to the lymph nodes and skin - this is tularemia. What it is?If literally, the name comes from Tulare - a region in the state of California, where it was first identified.
History and etiology
The causative agent is Francisella tularensis. It was first allocated in 1911 by employees of the anti-plague station G. Mc-Coy and Ch. Chapin from sick gophers in California. Later, in 1921, the disease was detected in humans. E. Francis called it a tularemia.
Tularemia in the USSR
In the Soviet Union, tularemia was first diagnosed in humans in 1926 when S. V. Suvorov, A. A. Volferts and M. M. Voronkova were identified as the pathogen from patients in the outbreak in the Volga delta. In the USSR, natural tularemia foci are recorded everywhere, including in Chukotka, Kamchatka, Sakhalin and in the Primorsky Territory.The northernmost outbreak was found on the Pyasina River (Taimyr Peninsula), and the southernmost - in Azerbaijan. Only Kyrgyzstan is free from tularemia.
Diseased tularemia zones are located in the north-west direction, in the central region, in the European southern and southeast region of the Soviet Union, as well as in the forest-steppe of Western Siberia, in Altai, Alatau and Tien Shan. In other regions, the infection is fixed mainly in river valleys, and in Transcaucasia - in the foothill and mountain regions.
In the Second World War and up to 1949, due to the increase in the number of rodents (due to the remaining uncultivated fields due to military operations), the incidence of tularemia increased significantly.In the following years, thanks to preventive measures, mainly vaccinations, the incidence of people decreased, and in 1967-1976. it amounted to about 125 infections each year. In the United States during this period recorded 161 cases.
Tularemia natural foci are located mainly in the regions of the northern hemisphere with a temperate climate. To the south, they are recorded in Mexico, Venezuela, and in the North - beyond the Arctic Circle. In Europe, tularemia is found everywhere in most countries, in Asia - in Iran, Turkey, China, Mongolia and Japan; on the American continent - in Mexico, Venezuela, the USA and Canada.
Sources of infection from vertebrate animals in natural conditions are rodents and hares. In the Soviet Union, the natural reservoir of the pathogen was found in wild vertebrates (82 species). All animals are divided into three groups according to the degree of sensitivity and sensitivity to tularemia. It is created by some small mammals that are especially sensitive to this disease (mammals of group I): vole, house mouse, muskrat, hare, hamster, etc. Internal organs, blood and excretions of sick or dead mammals have many tularemia microorganisms.
Mammals of the II group are small animals (gopher, squirrel, rat, field mouse, Far-Eastern vole), which are less susceptible to the disease.
Mammals of group III are the least susceptible to this disease: predatory: fox, raccoon dog, ferret, from domestic animals - cat and dog. They are almost irrelevant as sources of tularemia pathogen.
Transmission of this pathogen among mammals is carried out by means of transmissible arthropods, especially ixodid ticks, mosquitoes, and to a lesser extent fleas and gamasid ticks.Together with the bloodstream, food, contact infection (skin and mucous membranes) plays a secondary role, with the help of water, into which the secretions of an infected animal have fallen.
The development of an infectious process is determined by the following steps: penetration and primary adaptation of a microorganism, dissemination with the help of lymph, primary regional focal and general reaction of the organism, dissemination and generalization with blood, secondary foci, changes in reactive and allergic nature, reverse transformation and healing process. In the place of its penetration, the primary process with regional lymphadenitis or bubo often develops. Inflammation around the lymph node is moderate. The pathogen and its toxins enter the bloodstream, leading to bacteremia and the spread of the process and the development of secondary foci.
The incubation period lasts from 1 to 14 days. The disease has an acute onset, patients often even have a clear onset time. Chills and fever appear, the temperature rises to 38-40 degrees C. The patient complains of a feeling of pain in the head, weakness, dizziness, muscle pain, lack of appetite, and vomiting. Eyes and skin of a face of a red shade.In severe cases there is a delusional state, agitation, lethargy is extremely rare. Depending on the clinical forms, there are eye pains, pains on swallowing, chest pains, pains in the place of bubo development. The initial period is characterized by local changes associated with the entrance gate. Without antibiotic therapy, the fever lasts up to two to three weeks. Disease protracted and chronic forms can occur for several months. By the end of the first week, the liver and spleen are enlarged. The incubation period depends on the individual state of the immune system.
Tularemia - what is it? In the clinical picture, the following forms of flow are noted:
• Bubonic skin. This is the most common form - in 50-70% of cases.
• Eye-bubo. This form is rarely registered - in 1-2% of cases.
• Anginal-bubonic. It is fixed at 1%.
• Generalized (typhoid, septic). This form is the most difficult to diagnose.
Subject to the differential diagnosis of the disease with a characteristic increase in lymph nodes and tularemia, the symptoms of which can replicate other similar diseases, and not only infectious.This is a cat scratch disease, which is characterized by the presence of primary affect and regional lymphadenitis with an increase in the lymph node and frequent suppurations.
Complications develop in the form of meningitis, meningoencephalitis, pulmonary abscesses, pericarditis, peritonitis. However, cases of exacerbation and relapse are recorded.
It should be noted that tularemia is treated only in an infectious diseases hospital. What is it and how is this process carried out? Antibiotics are drugs for tularemia. The skin-bubonic form is not dangerous for a person and can pass spontaneously, however etiotropic therapy allows to speed up the healing process. The pulmonary form requires complex treatment with mandatory monitoring of the patient’s condition by specialists, since it can lead to dire consequences, even death. In the case of a chronic course, complex therapy with antibiotics and a vaccine is used. A killed vaccine is administered, administered in different ways at a dose of 1-15 million microorganisms at intervals of 3-6 days, a course of therapy — 6-10 injections.
In natural foci, rodents and ticks are controlled. Fishing for hares, water rats, hamsters, etc.reduces the population of animals and prevents the occurrence of epizootic.
Prevention of tularemia includes: sanitary inspection of the source of water supply, food facilities, warehouses and housing, preventing rodents from entering them, and vaccinating people who have been exposed to possible infection.
Of great importance is the sanitary-educational work among the population.
In case of epizooty, vaccinated population is vaccinated. In residential buildings, in warehouses, catering establishments carry out deratization. In the case of a transmissible infection, quarantine is established to visit the suspected site of human infection, they destroy the blood-sucking insects, use insect repellent repellents, PPE, Pavlovsky nets, etc. When infecting people in the fishery, they increase their control over the observance of sanitary veterinary requirements. When a water outbreak of tularemia immediately stop using water from a seeding source, the wells are disinfected.
Specific prevention of tularemia, or vaccination, is an effective method of preventing disease. Tularemia vaccine was developed by N. A. Gaysky and B. Ya. Elbert.Live dry skin vaccination against tularemia is available in ampoules in a lyophilized form, it is suitable for prolonged storage. In enzootic areas, vaccination is carried out as a planned event.
There is an associated vaccine against tularemia and brucellosis, as well as tularemia and other infections. Immune levels in vaccinated are assessed by an allergic response after a cutaneous tularin test. Timely vaccination of the population in the outbreaks in combination with other preventive measures led to a tangible result, a sharp decrease in the incidence was noted. Currently only sporadic cases are recorded.
At the present stage tularemia is a particularly dangerous infection. What it is? Medical scientists are asking this question, since this infection is of interest because of its pronounced natural foci and insufficient knowledge.