Tick-borne encephalitis - symptoms, prevention and treatment

Tick-borne encephalitis is an acute viral disease that affects mainly nerve cells in the human body. These can be structures of the brain, peripheral innervation or radicular nerve endings in the spinal cord.

The main source of infection is the ticks mite ticks. For the reproduction of these insects, the blood of an animal or a person is needed. Spring-summer seasonality is associated with the biology of tick-carriers. The virus, getting into the stomach of a mite with the blood of infected animals, penetrates all the organs of the mite and is transferred then to other animals, and also transmitted to the offspring of the tick (transovarial transmission of the virus).

The penetration of the virus into the milk of farm animals (goats) is proved, therefore, alimentary ways of infection of people through goats and cows are possible. Alimentary "goat" endemic foci of encephalitis have been established in various regions of the former Soviet Union.

Where is tick-borne encephalitis prevalent?

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Ixodid mites are common in forest and forest-steppe zones with a temperate climate. Several species of these parasites are known, but as a rule, tick-borne encephalitis occurs after bites of Ixodes Persulcatus (taiga tick) or Ixodes Ricinus (European forest mite). The first is more common in Asia, the second - in the territory of the European region.

Currently, tick-borne encephalitis is registered in almost the entire territory of Russia (registered about 50 territories of subjects of the Russian Federation), where there are its main vectors - ticks. The most unfavorable regions for morbidity are: the Urals, West Siberian, East Siberian and the Far-East regions, and from the adjacent to the Moscow region - Tverskaya and Yaroslavl.

The incubation period

The time from infection to the appearance of the first symptoms of tick-borne encephalitis is approximately 10-14 days. The incubation period can be extended for people who received immunizations from tick-borne encephalitis in childhood.

There are also several stages of the disease:

Lightning fast. With her, the initial symptoms appear already in the first day. In the absence of adequate treatment, a sick person quickly falls into a coma and dies of a central nervous system paralysis.
The protracted. In this case, the duration of the incubation period can be about a month, sometimes even slightly higher.

The first signs of the disease (which should be noted): usually a week after resting in nature, a person suddenly appears headache, nausea, vomiting that does not bring relief, fever up to 39-40 °, severe weakness. Then join the brain symptoms: paralysis of the limbs, strabismus, pain along the nerve endings, cramps, loss of consciousness.

Classification

The clinical classification of tick-borne encephalitis is based on the definition of the form, severity and nature of the course of the disease. Forms of tick-borne encephalitis:

Inpatient (subclinical):
febrile;
meningeal;
meningoencephalitic;
poliomyelitis;
polyradiculoneuritic.

According to the nature of the current distinguish between acute, two-wave and chronic (progredient) flow.

Symptoms of tick-borne encephalitis

After a tick bite, the virus multiplies in tissues, penetrates into the lymph nodes and blood. When the virus is multiplied and when it gets into the blood, flu-like symptoms form. The virus penetrates the blood-brain barrier and affects the brain tissue - neurological symptoms occur.

But the brightness of clinical manifestations, the speed of their growth and specificity always depend on which subtype of the disease and from the site of the localization of the virus.

European- it is characterized by 2 phases. The first manifestation is similar to the flu and lasts about a week. The second phase is characterized by lesions of the nervous system of varying degrees: from meningitis of mild form to severely leaking encephalitis.
Far Eastern- usually begins with a febrile state, proceeds acutely. Other symptoms can also grow quickly, leading to paralysis and coma. Lethal outcome can be as early as 6-7 days.

Despite a wide variety of symptoms and manifestations of the disease, four main clinical forms of tick-borne encephalitis are distinguished:

Feverish. The virus of tick-borne encephalitis does not affect the central nervous system, only symptoms of fever are manifested, namely high fever, weakness and aches in the body, loss of appetite, headache and nausea. The fever can last up to 10 days. The cerebrospinal fluid does not change, there are no symptoms of the nervous system. The forecast is the most favorable.
Meningeal. After a period of fever, a temporary decrease in temperature takes place, the virus at this time penetrates the nervous system, and again the temperature rises sharply, signs of neurological disorders appear. There are headaches with vomiting, severe photophobia and stiff neck muscles, symptoms of irritation of the brain membranes, there are changes in cerebrospinal fluid.
Meningoencephalitic. Characterized by damage to brain cells, which are characterized by impaired consciousness, mental disorders, convulsions, weakness in the limbs, paralysis.
Poliomyelitis. The onset of this form of the disease is manifested by severe fatigue, a general weakness. There is numbness in the body, after appear flaccid paralysis of the muscles of the neck and arms, proximal parts of the upper limbs. There is a syndrome of the "hanging head". Acceleration of motor disorders occurs within a week, after which the atrophy of the affected muscles occurs. The poliomyelitis form of the disease course occurs quite often, in almost 30% of cases. The course is unfavorable, disability is possible.

It should be noted that in different people the susceptibility to tick-borne encephalitis is different. With prolonged residence in a natural hearth, a person can undergo multiple sucking of ticks with the ingestion of small doses of the virus. After this, antibodies are produced in the blood, the accumulation of which promotes the development of immunity to the virus. If such people get infected, then the disease will proceed in mild form.

Diagnosis of tick-borne encephalitis

In the case of tick-borne encephalitis, diagnosis is carried out using tomographic studies of the brain, serological and virologic studies. Based on all indicators, an accurate diagnosis is established.

Damage to the brain is determined, first of all, based on complaints from a neurological examination with a doctor. The presence of inflammation and the nature of brain damage are established, the causes of encephalitis are determined.

How to treat tick-borne encephalitis

In the case of tick-borne encephalitis, there is no specific treatment. If symptoms appear that indicate central nervous system damage (meningitis, encephalitis), the patient should be immediately hospitalized to provide maintenance therapy. As a symptomatic treatment is often resorted to corticosteroid drugs. In severe cases, there is a need for intubation of the trachea with subsequent artificial ventilation.

Etiotropic therapy consists in the appointment of a homologous gamma globulin titrated against tick-borne encephalitis virus. Thanks to this drug, you can observe a clear therapeutic effect, especially if it is a serious or moderate disease. Gamma-globulin is injected 6 ml intramuscularly, every day for three days. The therapeutic effect is observed in 13-24 hours after the administration of the drug - the temperature of the patient's body comes back to normal, the general condition improves, the meningeal phenomena and headaches decrease, can even completely disappear. In recent years, serum immunoglobulin and homologous polyglobulin have been used to treat tick-borne encephalitis, which are obtained from the blood plasma of donors living in natural foci of tick-borne encephalitis.

Only 2-3 weeks after intensive treatment, under condition of normalization of body functions and stabilization of the condition, the patient is to be discharged from the hospital. Contraindicated hard work, mental overstrain. Regular walks are recommended, it is advisable to use means repelling ticks. Visiting a doctor is mandatory for two years.

Tick-borne encephalitis and its prevention

As a specific prevention of tick-borne encephalitis vaccination is used, which is the most reliable preventive measure. All persons residing in or endemic to endemic areas are subject to mandatory vaccination. The population in endemic areas is about half the total population of Russia.

In Russia, vaccination is carried out by foreign (FSME, Encepur) or by domestic vaccines in the main and emergency regimens. The main scheme (0, 1-3, 9-12 months) is performed with subsequent booster every 3-5 years. To form the immunity to the beginning of the epidemic season, the first dose is administered in the fall, the second winter. The emergency schedule (two injections with an interval of 14 days) is used for unvaccinated individuals who come to endemic foci in the spring and summer. Emergency provaccinated persons are immunized only for one season (immunity develops in 2-3 weeks), after 9-12 months they are given a third injection.

As an emergency prophylaxis when sucking ticks on unvaccinated people, intramuscularly inject an immunoglobulin from 1.5 to 3 ml. depending on the age. After 10 days, the drug is injected again in an amount of 6 ml.

Forecast

In tick-borne encephalitis, the prognosis for dysmenia depends on the degree of damage to the nervous system. At a feverish form, as a rule, all patients recover completely. When the meningeal form is also favorable, but in some cases, persistent complications from the CNS can occur in the form of chronic headaches, migraine development.

The focal form of tick-borne encephalitis is the most unfavorable by prognosis. Mortality can reach 30 people per 100 cases. Complications of this form is the emergence of persistent paralysis, convulsive syndrome, a decrease in mental abilities.

Where to get vaccinated against tick-borne encephalitis 2016?

In 2016 in Moscow in all administrative districts, from March to September, vaccination points are annually in operation at the bases of polyclinics, medical units, health centers of educational institutions: (in the Western administrative district - in the children's polyclinic № 119; in polyclinics for adults: №209, №162 and polyclinic МГУ №202), and also the Central vaccination point on the basis of polyclinic № 13 (st. Trubnaya, d. 19, building. 1 phone: 621- 94-65).

Where to conduct laboratory testing of ticks?

Investigations of ticks on infection by pathogens of natural focal infections are conducted in the Federal Center for Hygiene and Epidemiology, FBUZ "Center for Hygiene and Epidemiology in Moscow ", in the Central Research Institute of Epidemiology Rospotrebnadzor.
When contacting the laboratory, it is necessary to give information about the date and territory on which the tick sucked (region, region, populated point).

Where to conduct a laboratory blood test?

Persons suffering from suction of ticks on endemic territory can undergo a laboratory blood test (serological) on tick-borne encephalitis in the parasitological department of the microbiological laboratory of the FBSU "Hygiene and Epidemiology Center in Moscow ", or in any other laboratory that performs this type of research.