Tick-borne encephalitis

encephalitis mite
Encephalitis mite
encephalitis mite photo

Tick-borne encephalitis (spring-summer). The virus encephalitis, once in the stomach tick, then penetrates into all organs of the tick and accumulates in the salivary glands, ovaries and eggs. As a consequence, the pathogens are transmitted by ticks offspring transuralia and distributed animal hosts. Tick-borne encephalitis has a certain focal associated with the spread of ticks (taiga, marshlands), as well as seasonality, depending on time of hatching and of the greatest activity of ticks. In humans, the virus of tick-borne encephalitis hematogenous spread. Entrance gate of infection is superficial blood vessels, of which the virus enters into the internal organs and the nervous system.


The appearance of the patient tick-borne encephalitis:
1 - hanging head; 2 and 3 - atrophy of the muscles of the shoulder girdle.

The disease begins abruptly with a sharp headache, dizziness, vomiting, pains in the muscles, hyperesthesia, high temperature, photophobia. Face, sclera, the upper half of his body in the first days of the disease dramatically giperemiei, the skin is dry. Acute develops meningeal syndrome, on the 3-4th day of illness appear paralysis of the muscles of the neck and shoulder area. Head hangs on the chest (Fig., 1), muscle tone in the hands sharply reduced, later develop muscular atrophy (Fig., 2 and 3). Possible epileptiform seizures, loss of consciousness, often have mental disorders as confusion, delirium, hallucinations. Blood is marked leukocytosis to 10 000-15 000 with left shift formula, accelerated ROHE. The pressure of the cerebrospinal fluid is increased, more protein to 1-2%, the number of cells increased to 100-200 1 mm3 with a predominance of lymphocytes. The temperature falls to the 10-12-th day of illness, meningeal symptoms disappear, but the paralysis and seizures are often persistent. The disease may manifest itself in an easy, erased form. In expanded form in times of epidemics mortality reaches 25%. Transferred disease leaves a strong immunity.

Epidemiology
Foci of tick-borne encephalitis installed in several European and Asian countries. Diseases characterized mainly forest areas. In natural foci of the number of cases does not exceed several tens rarely hundreds of cases. Carriers of the virus of tick-borne encephalitis ixodid (pasture) ticks, mainly Ixodes persulcatus and Ixodes ricinus. They are the main keepers of the virus in nature. The virus entering the stomach mite when blood sucking infected animals, penetrates into all organs and reaches a maximum concentration in the salivary glands, and the ovaries and developing eggs in it. Thanks to this, is how transovarial transmission offspring mite, and spread it among animals proximately mites, in which the body the virus passes from the salivary glands in the period of krovotechenie. Temporary reservoir of the virus of tick-borne encephalitis are some wild animals (squirrel, field mice and other), as well as birds. The main role is played by ticks, as the virus remains longer than in rodents and birds and are transmitted to the offspring.
In settlements adult female mites prikarmlivayut on the cattle, goats, sheep and dogs. These Pets and create favorable conditions for the existence of tick-borne encephalitis and a two meningoencephalitis in inhabited areas. From animals infected goats are particularly epidemiological significance since the virus from them passed through nutritional (via raw milk). This often have a family and a group of diseases. Therefore, tick-borne encephalitis have people in connection with tick bites or by the consumption of infected goat milk (two meningoencephalitis). Diseases occur among rural residents and citizens while working in the forest, gathering berries, mushrooms, firewood, etc., infection is Possible and in the city: urban parks and groves. In the European part of the USSR infection through raw goat, iloko occurs in some cases of tick-borne encephalitis. The disease is characterized by seasonality: outbreaks occur in spring l summer (may-July). In some areas they are registered in August and September.


The clinical picture
Vernal (spring-summer) encephalitis. The incubation period 7-20, often 10-12 days. The disease starts acutely, often suddenly. The body temperature rises up to 39-40°, there is a strong headache, nausea, vomiting, may experience epileptic seizures. In the first days of the disease may develop disorders of consciousness: more oglushennosti, Zaporozhie state of delirium. When the study show a clear meningeal symptoms (meningoencephalitides syndrome). The cerebrospinal fluid is clear, bright, for the amount of protein increased to 1%, and lymphocytic pleoticus (100-300 cells in 1 mm3). On the background of meningeal phenomena can develop flaccid paresis, and paralysis of the upper extremities and neck muscles (poliomyelitiso syndrome). In severe cases, join the symptoms of an oblong brain: problems with swallowing, slurred, slurred speech, shallow, rapid breathing, frequent, small irregular heartbeat (polioencephalomalacia syndrome). Rarely observed eye disorders, ptosis, paralysis of the facial nerve, masticatory muscles in connection with the defeat of the kernels of the corresponding cranial nerves (polioencephalomalacia syndrome). Sometimes the disease occurs by type washedaway paralysis, beginning with the lower limbs and extending up to the muscles of upper extremities (see Landry ascending paralysis). Death occurs when events bulbar palsy centers on the 2nd or 3rd day of the disease.
In the period of epidemic outbreaks of encephalitis are most widely spread erased form of the disease characterized by 3-5-day fever without clear signs of defeat of the nervous system, and meningeal form with a picture of serous meningitis (see) and mild cerebral symptoms.
Febrile period usually lasts 5 to 10 days. Meningeal symptoms and paralysis occur in the first days of the disease. If you erased and meningeal forms relatively full recovery. Sometimes can be prolonged asthenic conditions, headaches, loss of memory and mental performance. Movement in paralyzed muscles recover, as a rule, in part, observed or that the degree of their atrophy. The most characteristic paresis and atrophy of the muscles of the neck (hanging head) and proximal upper extremities. Sometimes even erased after the initial manifestations of the disease can be purchased progressive, chronic course. 3-6 months. after apparent recovery or stabilization painful manifestations growing residual paresis, there flaccid paralysis not previously affected muscle groups (syndrome of chronic polio). Often in paritychecking and atrophic muscles are marked fibrillar twitching. In some patients, such atrophic paralysis of limbs combined with a sharp increase deep reflexes and other pyramidal symptoms. Clinical presentation and course of the disease in these cases correspond to the syndrome of amyotrophic lateral sclerosis (see).
Typical manifestations of chronic encephalitis also include syndrome Kozhevnikovsky epilepsy (see). It is expressed in constant, random, rapid reductions of certain muscles and muscle bundles (mioclonii), exciting usually half of the body. Occasionally myoclonic hyperkinesia increases and ends General epileptic fit.
Clinic and clinical outcome vary widely in different areas. In the Western regions of the USSR and in Central Europe is dominated by light meningeal disease with mortality rates, not exceeding 1%; in the far East frequent paralytic form and mortality reaches 20%.

Tick-borne encephalitis in children is less common than in adults who on working conditions can often be subjected to tick bites. In children is more common nutritional route of infection. After an incubation period of 2-7 days for patients receive high fever, headache, repeated vomiting. Often disturbed consciousness, there are convulsions, delirium. Sometimes the disease occurs only in the form of serous meningitis, but more often appear peripheral type the paralysis of the muscles of the neck and shoulder area, which can be combined with the tabloid disorders (poliomyelitisa form). When cerebral form of the notes the development of hemiparesis, lesions of the cranial nerves and other focal symptoms. Often, the children develop the syndrome Kozhevnikovsky epilepsy.