From Big Medical Encyclopedia

TICK-BORNE ENCEPHALITIS (encephalitis acarinarum; Greek enkephalos a brain + - itis; synonym: tick-borne encephalomyelitis, vernal spring and summer encephalitis, taiga encephalitis) — the natural and focal infectious disease which is characterized by preferential damage of the central nervous system. Proceeds sharply, in some cases accepts a chronic progreduated current.

History. Studying E. to. began in 1937 when to the Far East the expedition led by JI was sent. A. Ziljber. Then in the centers E. to. expeditions led by E left. N. Pavlovsky (1938) and I. And. Rogozin (1939) «A result of work of these expeditions was discovery of a virus — an infestant, identification of animals — sources of the activator, the proof of a role of ixodic mites in circulation and preservation of a virus in the nature and infection of the person, establishment of the main epidemiol. patterns E. to., development of nonspecific and specific measures of prevention, methods of a serotherapy. In 1939 on the basis of the researches conducted under the leadership of M. P. Chumakov existence of the centers E was proved. to. outside the Far East. After 1945 researches of the natural centers E were continued. to. in the territory of the Soviet Union and many countries of Eastern, Central and Western Europe. In 60 — the 70th studying of interaction of a virus with cells, its morphogenesis, genetics and molecular structure began. Works on creation of new vaccines on the basis of achievements of molecular biology gained development.

Considerable group of the scientists who made a big contribution to studying of a tick-borne encephalitis — E. N. Pavlovsky, A. A. Smo-rodintsev, JI. A. Zilber, E. N. Levkovich, M. P. Chumakov, V.D. Solovyov, A. K. Shub-ladze, P. A. Petrishcheva — are conferred State awards of the USSR.

Geographical distribution.

In a crust, time E. to. it is widespread in extensive territories of Europe and Asia. In the Soviet Union diseases register in RSFSR, Belarus, in Ukraine, in Latvia, Lithuania, Estonia, Kazakhstan and Kyrgyzstan. In RSFSR the centers E. to. are found in Primorsk, the Khabarovsk, Krasnoyarsk and Altai regions, in the Tomsk, Omsk, Novosibirsk, Kemerovo, Perm, Sverdlovsk, Arkhangelsk, Leningrad, Smolensk, Kalinin, Vologda, Kirov and Yaroslavl regions, in Udmurt, Tatar and Karelian by the ASSR. The greatest number of diseases is noted in Western Siberia and in the Urals. The most cases E falls to the share of these regions. to., registered in RSFSR. Outside the USSR a tick-borne encephalitis is registered in many countries of Europe. There are data on identification of the natural centers E. to. in Mongolia. Cases E. to. observed in sowing. provinces of China. It was reported also about identification E. to. in the territory of DPRK.

Etiology. Activator E. to. PH About the holding virus belonging to the sort Flavivirus, this is. Togaviridae. Virus E. to. contains single-stranded, linear, infectious RNA with relative a pier. it is powerful (weight) apprx. 4 X 10b. Virion has spherical shape, diameter apprx. 50 nanometers, contains a nucleocapsid to dia. 25 — 35 nanometers with ikosaedralny symmetry. It is surrounded with the lipopro-teidny cover covered with gli-koproteidny shoots of 5 in size — 10 nanometers. The hemagglutinating activity of a virus is connected with these shoots. Three virus proteins are described: glikozilirovanny the shell about a pier. weighing 53 — 63 X 103, nukleokapsidny about a pier.

weighing 1,35 X 103 and minor about a pier.

weighing 7,7-8,5 X 103.

The virus is sensitive to ether and a misinformation-oksikholatu. Under the influence of 5% of solution of lysol or 5% of solution trichloroacetic to - you the virus perishes. Formalin inactivates infectious of a virus and does not influence an immunogenicity of virus protein. Effect of formalin amplifies at temperature increase. Beta propiolactone completely inactivates infectious, but does not influence the hemagglutinating or complement-linked ability of a virus that is used at preparation of diagnostic drugs. Virus E. to. it is easily inactivated at high temperatures; in suspension of brain fabric at t ° 37 ° he perishes in 48 hours, at t ° 60 ° — in 10 min., at t ° 100 ° — in 2 min. In cow's milk at t ° 4 ° the virus remains without decrease in an infectious caption of 2 weeks, and in sour cream or oil it is found up to 2 months. It is long remains in 50% solution of glycerin (pH 7,2) or in the lyophilized state.

In vitro agglutinates erythrocytes of a ram (at pH 6,4 — 6,9), newborn chickens (at pH 6,1 — 7,0) and a goose (at pH 6,5 — 7,0). Breeds, as a rule, without cytopathic effect in primary and intertwined cultures of cells of various origin. Destroys in vitro of a cell of a renal epithelium of pigs. Under a layer of an agar covering negative colonies are formed. In cultural liquid collect thermostable gemagg lyutinina.

To a virus E. to. newborn and adult white mice, suckers of white rats, hedgehogs, hamsters, pigs, goats, monkeys etc. are sensitive. Mice get sick at infection in a brain, under skin, in an abdominal cavity and through a mouth. The virus causes hron. an infection in culture of cells and at experimental animals. Suppression of an immune response of the owner promotes development of a virus persistention in c. N of page.

On the basis of studying of an antigenic structure of a virus E. to. allocate the western and east options. Zones of distribution of these options match areas of their carriers — Ixodes ricinus and Ixodes persulcatus (see. Ixodic mites). Options of a virus E. to. call also ritsinusny and persulkatus-ny.

V. I. Votyakov, I. I. Protas,

V. M. Zhdanov (1978) consider that antigenic options of a virus of a tick-borne encephalitis are activators of two different nozogeografi-chesky forms of a disease — western and east.

There are viruses, antigenically related to a virus E. to. and forming together with it a complex (group) as a part of the sort Flavivirus. Viruses of the Scottish encephalitis (see), the Omsk hemorrhagic fever (see), the Kjyasanursky wood of a disease (see), Povassan, Negisha and Langat belong to this antigenic group (see Togavirusa).

Epidemiology. A source of a contagium are mammals and birds. Very actively the hedgehog, a mole, a small and ordinary common shrew, a squirrel, a chipmunk, red and red voles, a hazel grouse, a chaffinch, a thrush, etc. are involved in circulation of a virus. Near settlements epizootic process joins cows and goats. It is shown that the virus can it is long to worry in a brain of nek-ry mammals (e.g., voles) and birds, without causing in them clinically expressed symptoms of a disease.

Main tank of a virus E. to. in the nature and its carrier ixodic mites of I. persulcatus and I. ricinus are (see fig. to St. Ixodic mites, t. 9, Art. 69). In circulation of a virus also

I. pavlovskyi, Haemaphysalis concinna, Dermacentor silvarum, etc. can take part in the nek-ry centers. Mites pass long (up to three years) a development cycle, for to-rogo change of the animals owners who are prokormitel of mites on the course metamorphoses ability of mites in each phase of development to be sated on vertebrate animals of different types (see is characteristic. Ixodic mites). Approximately at 100 species of mammals and more than at 170 bird species parasitizing of ixodic mites is revealed. At mites the virus is transmitted transfazovo and transovarialno. He lives in an organism of I. persulcatus probably during all life of a tick. Infectiousness of mites in the majority of the natural centers averages apprx. 2%, on the course their metamorphosis infectiousness significantly decreases.

The person catches E. to. by a transmissible way during attack on it of the infected ixodic mites, to-rye transmit a virus with saliva. Ixodic mites eat blood continuously within several days. The longer the infected mites eat on the owner, the more probable it infection. Alimentary transfer of a virus with milk of the infected goats or cows is proved. In 50 — the 60th in Belarus almost in 75% of cases of diseases E. to. goats were sources of a virus. In a crust, time in connection with reduction of a livestock of these animals the alimentary way of infection has smaller value. Laboratory cases of infection at hit of a virus in respiratory tracts are described, on the injured skin or on a mucous membrane of eyes. Diseases at contact with patients are not registered.

Distinguish the following types of the centers E. to.: natural and antropourgiche-sky. The natural centers are in undeveloped or few forest and forest-steppe arrays mastered by the person, on pastures, tracks of wildings where «prokormitel» of ixodic mites are wild hoofs, large predators, forest rodents, birds of the lower tier of the wood. Natural centers E. to. are not equivalent across Epi-demiol. importance. In a number of districts of the country, napr, in the Urals, there are regularly new centers, i.e. cases in earlier safe on E are registered. to. districts and attenuation of the old centers. The reasons of fluctuation of activity of the centers are studied insufficiently. The Antropourgichesky centers are located near settlements of the person; they resulted from its activity and are connected with forest pastures of house hoofs. The centers can be in forest-steppe, steppe zones (in beams, ravines), on valleys of the rivers, on the sites covered with the wood in shrubby thickets. Prokormitelyami of adult mites in these centers are domestic animals.

For E. to. the expressed seasonality of incidence is characteristic that found reflection in the name of a disease — spring, summer or spring and summer encephalitis.

Diseases E. to. begin to register after establishment of above-zero temperature of air; the first cases are observed in April, reach a maximum in the first or second decade of June, then begin to decline, however isolated cases are possible in September, is rare in October. Seasonality of diseases E. to. it is caused by the period of activity of ixodic mites — carriers of a virus. The maximum of their activity is noted in spring months; at the end of summer there is the second period of rise in number of active mites. Unequal seasonality E.k is noted. among representatives of different professions. Persons, constantly connected by the nature of work with the wood, get sick, as a rule, during the spring and summer period. The persons who are engaged in collecting and preparation of mushrooms and berries catch at the end of June — July. On character of a seasonal curve E. to. weather has significant effect: if summer cold and rainy, greatest number of cases E. to. register in the second half of July and in August.

In the last decades changes of list of patients E are noted. to. Before the Great Patriotic War and in the first years after war persons, a profession got sick preferential to-rykh it was connected with long stay in the wood. In a crust, time for their share it is necessary on average apprx. 20% of the cases registered in RSFSR E. to. The ground mass of patients is made by the people visiting the wood for the purpose of rest, gathering berries, mushrooms, etc. Higher rates of incidence usually are registered among villagers since owing to working conditions and life they are exposed to risk of infection more often. E.g., in RSFSR incidence of villagers in

1950 — 1967 approximately twice exceeded incidence of urban population; it was the share of children of preschool and school age on average apprx. V3 of the diseased.

The most cases of diseases (70 — 80%) is observed in the antropour-gichesky centers.

Pathogeny. The virus extends in the hematogenous way, but in c. the N of page can get and perinev-ralno. The observed destructive defeats of neurons are not only a consequence of direct action of a virus, but also result vascular mezenkhimnoy reactions. A pathogeny at hron. progreduated disease, for to-rogo increase of symptoms of defeat of c is characteristic. the N of page, is studied insufficiently. The role of a long persistention of a virus in ts.n.s is authentically established. and its value (in combination with hereditary and immune insufficiency) in development hron. forms of a disease.

The pathological anatomy of a tick-borne encephalitis of the person is described I. A. Robinzon, Yu. S. Sergeyeva (1939) and I. S. Glazunov (1940). The most expressed and characteristic for E. to. disturbances come to light in c. N of page. Sharp hypostasis and a thickening of a soft cover back and a brain, a plethora of vessels and infiltration of fabric lymphoid cells are found. Tissue of a brain is surprised diffuzno. In it the expressed vascular and mesenchymal reaction is noted; multiple massive perivascular infiltrates are found. At the same time early there is a proliferative component of inflammatory reaction, sharp hypostasis of tissue of brain, the expressed disturbances a face-vorodinamiki and a hemodynamics come to light. Ney-rotropnost virus E. to. causes primary damage of motor neurons back and a brain with the subsequent neyronofagiya (see). At the same time growths of cells of the microglia which is exposed to degenerative changes and then proliferation and a hypertrophy of an astroglia with formation of glial hems are found. The most expressed changes are observed in front horns of cervical segments of a spinal cord, in kernels of motive cranial nerves and kernels of a reticular formation.

Morfol. changes come to light also in other bodies and fabrics. The plethora of internals is noted, small hemorrhages in an endocardium and an epicardium, a pleura, on a mucous membrane of a stomach and intestines, and also a hyperplasia and a plethora of a spleen, dystrophic changes of a liver are found.

Immunity at the persons who transferred E. to., in most cases resistant. Recurrent diseases, as a rule, are not observed. Individual insufficiency of immune system can lead to development hron. diseases.

Clinical picture. Wedge, current E. to. differs in considerable polymorphism. At acute disease distinguish the following forms: feverish, I proceed

Shuya with symptoms of the general intoxication without signs of defeat of a meninx and a nervous system; meningeal, at a cut the leading sign is the serous meningitis which sometimes is combined with poorly expressed quickly passing signs of diffusion defeat of c. N of page; focal forms — encephalitic, hemiplegic, poliomiyelitichesky, en-tsefalopoliomiyelitichesky, polioencephalitic, hyperkinetic, the leading sign to-rykh — focal defeat of a nervous system.

The incubation interval varies ranging from 8 up to 23 days, but in most cases — from 10 to 14 days. The prodromal stage is observed at 10 — 15% of patients, it proceeds in the form of weakness, an indisposition, mild passing muscular pains, feeling of alarm. Irrespective of a wedge, forms E. to. in all cases the disease begins sharply with symptoms of the general intoxication. Nausea, vomiting, fever, dermahemia of the person and Tula-vshtsa, severe headache are characteristic sharp rise in temperature to 39 — 40 ° above. Quite often fever has dvukhvolnovy character, at the same time a wedge, symptoms differ in the greatest expressiveness during the second wave of rise in temperature. On this basis nek-ry researchers allocated a special nosological form — a dvukhvolnovy encephalomeningitis. However further it was shown that it has no etiol. distinctions with

E. to., but is registered by transfer of a virus with milk of goats or cows more often.

Sometimes the disease begins with an epileptic seizure. In some cases fibrillar and fascicular twitchings, passing local feeling of numbness, napr, sites of skin of extremities are observed. At various wedge, forms E. to. the polyneuritic syndrome is sometimes observed (see the Polyneuritis.), characterized by pains and feeling of a pricking on the course of nervous trunks, disorders of sensitivity of skin, etc.

The feverish form is limited only to the symptoms of the general intoxication described above, to-rye 3 — 6 days last on average.

The meningeal form develops in most cases diseases E. to., it also begins with symptoms of the general intoxication, duration to-rykh makes

5 — 10 days; then there is an expressed meningeal syndrome — a sharp headache, muscle tension of a nape, a Kernig's sign, etc. (see Meningitis); in cerebrospinal liquid (see) preferential lymphocytic pleocytosis, usually in limits to 100 — 200 cells in 1 mkl, and occasionally small increase in protein content to 0,1 — 0,2 ° is found/00 (g/l). Changes of cerebrospinal liquid are quite often observed rather long — of 2 — 3 weeks to several months.

After the postponed meningeal or feverish form E. to.

Fig. Bolny, transferred a poliomiyelitichesky form of a tick-borne encephalitis (the residual phenomena in 4 years after the acute period): atrophy of muscles of the left

shoulder and shovel.,

often for a long time (up to several months) there can be an asthenic syndrome (weakness, headaches, irritability, etc.). Focal forms differ in the following the most characteristic a wedge, manifestations. The encephalitic form is characterized by all-brain symptomatology — a headache, epileptiform attacks, mental disorders, disturbances of consciousness, defeat of the respiratory and vasomotor centers (an asthma, disturbances of a respiratory rhythm and change of arterial pressure). The listed phenomena pass usually during 1 — 2 week, but after that there is a long asthenic state. The hemiplegic form is observed generally at elderly people; on the manifestations she reminds vascular damages of a brain (sharply developing disturbance of consciousness, paresis, paralyzes). At a poliomiyelitichesky form against the background of an all-infectious syndrome at the patient sluggish paralyzes of muscles of a neck and upper extremities (is more rare than lower) in various combinations (fig.) develop. At the same time in the affected extremities fascicular and fibrillar twitchings, passing disturbances of sensitivity can come to light. Increase of motive disturbances can last up to 7 — 12 days. The Entsefalopoliomiyelitichesky form consists of signs of poliomiyelitichesky and encephalitic forms, is characterized by a heavy current and a failure. A polioencephalitic form — the heaviest since at it preferential motive kernels of a brain trunk and respectively the vital centers suffer that leads to disturbances of breath, cordial activity, swallowing, etc. The hyperkinetic form is more often observed at young age, development of kozhevnikovsky epilepsy (see), a myoclonus epilepsy (see) or the general epileptiform syndrome is characteristic of it (see. Epileptiform syndrome).

In a small part of cases (1 — 2%) acute disease at once or later a long time (up to 3 years) is replaced by chronic progreduated. Hron. the current is expressed by increase of the being available symptoms of defeat of a nervous system or emergence of new. According to this or that form of an acute current there are hyperkinesias (see), epileptiform attacks, degree of paresis, muscular atrophies raises. The hyperkinesia is shown preferential in muscles of a shoulder girdle, a neck and the person, it can be combined with generalized convulsive attacks. The atrophy of muscles develops preferential in proximal departments of upper extremities. Fibrillar twitchings of muscles and disturbance of sensitivity are noted.

Mental disorders at E. to., as in acute, and hron. stages, are observed quite often. In a prodromal stage the adynamic adynamy prevails (see. Asthenic syndrome). At acute disease mental disorders are presented by exogenous type of reaction (see Bongeffer exogenous types of reaction, t. 10, additional materials), first of all conditions of devocalization of consciousness, various on depth (see Devocalization). Arise a delirium much less often — professional or mussitans (see. A delirious syndrome), an amental syndrome (see), epileptiform excitement (see Epilepsy). Emergence in an onset of the illness of epileptiform attacks, even single, and also the pictures delirium acutum (see) testifies to an opportunity in the subsequent development at acute disease of deep stupefaction (see Consciousness, disorders of consciousness), in particular a coma, and to probability of death. On a minovaniya of mental disorders amnesia is observed (see).

In the period of reconvalescence the combination of the expressed adynamy to dysmnesias is characteristic (see Amnesia) up to development of a korsa-kovsky syndrome (see). Usually disturbances of memory are reversible. Children and teenagers have dysmnesias and decrease in intelligence can be resistant and reach degree of weak-mindedness (see). At the two-wave nature of disease in the period of reconvalescence quite often there are conditions of stupefaction.

At hron. disease mental disorders differ in polymorphism. The psikhopato-podoony disturbances which are shown hysterical frustration (see Hysteria) or excitement (see Psychopathies) or change of mood as a cyclotymia are possible (see. Maniac-depressive psychosis). And depressivnoipokhondrichesky symptoms prevail. Psychopatholike disturbances are always combined with an adynamy. In some cases develop kozhevnikovsky epilepsy with the changes of the personality close to epileptic, disturbances of mentality, similar observed in hron. stages of epidemic encephalitis (a bradyphrenia and psychopatholike disturbances with dominance of frustration of inclinations), the shizofreno-like psychoses which are followed by hallucinations and nonsense (see Schizophrenia).

Complications. Accession of consecutive infection and toksi-to-allergic defeats of various bodies, napr, pneumonia, nephrite, myocarditis are possible.

The diagnosis is based on data epidemiol. the anamnesis (accommodation in the local center, visit of the wood, detection of the stuck tick, time of a disease), a wedge, diseases and results of laboratory researches.

Laboratory diagnosis is based on allocation of a virus or identification of increase of quantity of antibodies in blood (see. Virologic researches, Serological researches). The virus can be allocated from blood and cerebrospinal liquid. Material is entered into a brain of mice and single-layer cultures of cells. The diagnostic value of various serological tests at E. to. changes depending on the term of a disease. So, up to 21st day the greatest number of affirmative answers (to 50%) by results of inspection of pair serums is given by reaction of suppression of hemagglutination (RPGA), then a neutralization test (in culture of fabric — 33% of affirmative answers, at infection of white mice — 30%) and RSK (23% of affirmative answers). On 6 — the 9th week of a disease etiol. the diagnosis by means of RSK can be made at 96% inspected during the use of other methods — at 80 — 85%. For acceleration of serological diagnosis recommend to investigate one sample of blood serum taken in an onset of the illness; identification of antibodies of the class IgM speaks well for E. to. Nek-ry researchers use with the diagnostic purpose reaction of diffusion precipitation in an agar (RDPA) and reaction of indirect hemagglutination (RNGA). However these methods were not widely adopted. In a crust, time for laboratory diagnosis E. to. and detection of a virus in carriers applies them-munosorbentnye methods — a radioim-munologichesky method (see) and an immunoenzyme method (see Enzim-im-munologichesky a method).

In the nek-ry centers E. to. register considerable number of cases (sometimes to 50? ^) so-called seronegative options of a disease when it is not possible to reveal antibodies to a virus. Their origin is explained with existence of the inborn or induced immune defects. Usually at E. to. formation of fixators in comparison with antigemag-glyutinina is slowed down. At fever of two-wave character oppression of products of the fixators and antibodies neutralizing in the vivo virus takes place long (up to 1 month).

The differential diagnosis should be carried out with the Japanese encephalitis (see Encephalitis mosquito), a North Asian tick-borne rickettsiosis (see), poliomyelitis (see), a hemorrhagic nephrosonephritis (see).

The Japanese encephalitis differs in preferential autumn seasonality. At a North Asian tick-borne rickettsiosis primary affect on site a sting of a tick which is followed by regional lymphadenitis, rash on a body preferential the rozeolezno-father-leznogo of character is observed; symptoms of encephalitis arise seldom and at the same time are poorly expressed; course of a disease high-quality. The gradual beginning, poorly expressed meningeal syndrome, sudden development of paralyzes with 4 — the 6th day of a disease is characteristic of poliomyelitis. In a wedge, a picture of a hemorrhagic nephrosonephritis into the forefront signs of damage of kidneys (a back pain, sharp morbidity, even act at easy effleurage in a waist, a massive proteinuria, an azotemia, an oliguria, etc.), and on this background signs of defeat of c can already be noted. N of page.

The final diagnosis can be established on the basis of results of virologic and serological researches.

Treatment is defined by features of defeats of a nervous system and the nature of disease. At the beginning of a disease of the patient it is necessary to provide the maximum rest, to limit the movements. Transportation in a hospital shall be sparing. As soon as possible (in the first 3 days of a disease) enter the immunoglobulin of the person titrated on antibodies to a virus of a tick-borne encephalitis. It is received from placental blood of the women in childbirth living in regions of the natural centers of a tick-borne encephalitis. Appoint dehydrational therapy (lasixum, furosemide, Diacarbum, etc.), vitamins of group B, symptomatic means (analgetics, cardiovascular means, etc.). Resort to introduction of antibiotics and streptocides only at emergence of complications (pneumonia, inflammatory processes in urinary tract, etc.). At epileptiform attacks apply anticonvulsants. At emergence of signs of development of any focal form E. to. appoint inside Prednisolonum from calculation to 1,5 mg! kg a day, at the same time salts of potassium, a proteinaceous diet. Extremities are given functionally correct situation, appoint passive easy gymnastics, massage, physical therapy (an ionophoresis with potassium iodide, a diathermy, parafino-, an ozoceritotherapy, etc.). It is very important to use a complex of the means contributing to normalization of a homeostasis. In case of disturbance of breath and function of the vital centers of a brain trunk of the patient transfer to the intensive care care unit. At disturbance of motive functions in the early recovery period increase volume to lay down. physical culture and massage. At emergence of a tendency to hron. disease should limit exercise stresses, including and connected with to lay down. procedures since they can promote sharp strengthening of weight of a disease, deepening of motive disturbances. For the same reasons for the persons who transferred E. to., balneoterapiya and dignity. - hens. it is necessary to appoint treatment carefully.

The most difficult is treatment of patients at chronic disease. Appoint the anticonvulsant drugs, drugs improving exchange processes in nervous tissues, cholinolytics, tranquilizers, fortifying means; exclude exercise stresses, the balneoterapiya and electroprocedures are contraindicated.

The forecast depends on a form and weight of disease. Feverish and meningeal forms in most cases come to an end with an absolute recovery. At focal forms, especially at extensive defeats of motor-neurons of front horns of a spinal cord, the resistant residual phenomena resulting in disability of the patient are frequent. The worst forecast at polioencephalitic and en-tsefalopoliomiyelitichesky forms, to-rye are followed by the highest lethality. At hron. disease the forecast adverse owing to an invalidism of sick and frequent lethal outcomes.

Prevention is based on use of specific and nonspecific means of protection. Vaccination and administration of protivokle-shchevy immunoglobulin belong to specific means (see Immunization). Active immunoprevention E. to. it is carried out only by means of the inactivated vaccine. All attempts to create a live vaccine ended with failure, and to a crust, time theoretical premises are not developed for receiving safe attenuirovanny virus strains. The first option of the inactivated vaccine from the virus which is grown up in a brain of mice was created and tested in practice in the late thirties — the beginning of the 40th years. The vaccine prepared from a brain of mice had the expressed reactogenicity caused by the high content of alien tissue of brain. In the 60th the inactivated vaccine from the virus which is grown up in culture of cells of in vitro was created. For increase in an immunogenicity used adsorption of a virus on aluminum hydroxide. Drug was malore-aktogenny, however its efficiency was insufficient. At the beginning of the 80th in Ying-those poliomyelitis and viral encephalitis of the USSR Academy of Medical Sciences the concentrated inactivated maloreaktogen-ny vaccine against E was developed. to. with the raised immunogenicity.

For prevention E. to. recommend to the persons which were attacked by ixodic mites administration of immunoglobulin with the high content of antibodies against a virus that reduces probability of a disease by 3 — 5 times.

Success of vaccinal prevention E. to. depends on correctness of purpose of vaccination to certain groups of persons. First of all it is necessary to impart the villagers living in the territory of the natural center, the workers of forestry and all persons going to districts of circulation of a virus (tourists, employees of various expeditions, builders, etc.).

Nonspecific prevention E. to. it consists of a package of measures of protection against attack of ixodic mites. Individual protection first of all is based on use of antitick-borne clothes — Zhukova's suit developed Ying volume of medical parasitology and tropical medicine and the All-Russian Research Institute of the knitted industry. The suit interferes with penetration of mites under clothes and to suction of blood by them through fabric. It is reached by means of two shirts: lower — from coarse thick fabric and upper — from close-meshed fine fabric, edge well passes air. Through small cells of an upper shirt ixodic mites do not get, and thanks to thick fabric of an undershirt the proboscis of a tick does not reach a body surface of the person. Trousers with a soft elastic belt and elastic knitted cuffs of an upper shirt and trousers interfere with a zapolzaniye of mites under clothes. The hood of an upper shirt or a cape protect the head and a neck. In cold and rainy weather put on a jacket. Zhukova's suit was an effective remedy of protection not only against mites, but also from kokhmar (see Mosquitoes blood-sicking), and also midges (see). As means of antitick-borne protection also the usual clothes can * be used, but it is necessary to put on it so that to exclude a possibility of penetration of mites under it. The shirt is filled in trousers, and by trousers — in boots or socks, cuffs and a collar densely clasp, put on the hood protecting a neck the head. Efficiency of antitick-borne clothes increases during the processing by its repellents (see).

Carry out self-surveys and mutually wasps-motry for identification and removal from clothes or a body of mites. Inspections are performed, without taking off clothes, about an every 2 hour stays in the centers of mass distribution of mites (on pastures house and wildings, tracks of wildings in a taiga, etc.). During these surveys delete the ticks noticed on outerwear and on open parts of a body. In a lunch break and after work perform inspection of a body for the purpose of detection of the ticks who were in time to creep under clothes or to be attached to skin under clothes. For survey choose the place where obviously there are no mites, but not in premises since mites can creep away from clothes and then attack people. The self-surveys and mutually surveys offered E. N. Pavlovsky, are very effective measure of prevention E. to. It is based that ixodic mites in the first 2 — 3 hours of a krovososaniye give rather small doses of the activator and though, perhaps, infection occurs, but the dose of the activator is insufficient to cause a disease.

The organization a dignity is obligatory. - a gleam. works among country people and citizens living in the territory of the natural center (see. Sanitary education).

The question of use of acaricides (see) for extermination of ticks in territories where activity of the person is developed is very difficult. They give undoubted anti-epidemic effect, however side effect of acaricides in the environment is so big (extermination of many useful insects, destruction of ecological bonds, death of birds, damage to livestock production, etc.) that the question

of expediency and a possibility of their use shall be solved in an individual order competent authorities.

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