Tick-borne encephalitis is an acute infectious disease characterized by fever, intoxication, and damage to the nervous system, leading to the development of paralysis.
The causative agent of the disease is a virus that can survive for a long time at low temperatures and in a dried state. But the virus quickly loses activity at room temperature, and boiling kills it within 2 minutes.
The tick-borne encephalitis virus is found in the body of ixodid ticks, some large and the bulk of small forest mammals (rodents, insectivores), and some species of birds. Ticks are the main keepers of the virus in nature, in which it exists indefinitely, being transmitted to offspring. Wild animals store the virus for a short time. Also, viruses can multiply in the body of some domestic animals, for example, goats, sheep and cows, which do not show signs of the disease. If the tick-borne encephalitis virus is in the blood of cows and goats, then it is likely to get into their milk.
Human infection occurs by sucking a tick infected with the tick-borne encephalitis virus, as well as by eating raw milk of goats and cows or products made from infected milk that has not undergone heat treatment (cheeses, for example).
The disease is characterized by natural foci, i.e. its distribution requires a certain set of climatic conditions, the presence of appropriate vegetation and terrain, ensuring the likelihood of the existence of infection vectors – ticks. Characterized by spring-summer and summer-autumn seasonality associated with periods of greatest activity of ticks.
Having entered the body through the site of a tick bite, the tick-borne encephalitis virus enters the bloodstream and penetrates the cells of the central nervous system, causing severe changes in them.
The patient as a source of infection for others is not dangerous.
The transferred disease leaves a persistent immunity to the disease, but in some people the virus is stored in the body, causing chronic forms of the disease.
The incubation period lasts from 1 to 30 days. The disease begins suddenly with chills, a rapid increase in body temperature to 38-39C. The temperature lasts 5-10 days. The patient is worried about a severe headache, pain throughout the body, fatigue, weakness, sleep disturbance, nausea, and sometimes vomiting. The patient’s face and eyes are red. From 3-5 days of the disease, damage to the nervous system develops: lethargy, drowsiness, delirium, hallucinations, motor agitation, sometimes convulsions develop.
In some patients, the disease is complicated by paralysis of the muscles of the neck and upper limbs: there is weakness in the arm or leg, up to the complete improbability of making movements; with the development of such paralysis in the muscles of the neck, a “hanging head” is observed. Quite a characteristic sign of tick-borne encephalitis are involuntary twitches of individual muscle groups. There may be a feeling of numbness of the skin in certain parts of the body. In severe cases of the disease, there may be slurred speech, choking, difficulty swallowing.
A formidable complication of tick-borne encephalitis is respiratory failure: frequent or infrequent breathing, short-term respiratory arrests that occur, which can result in complete respiratory arrest and death of the sick person.
Based on clinical data (characteristic signs of the disease); epidemiological data (stay of the sick person in endemic areas, a history of visiting the forest, the fact of sucking a tick, the correspondence of the season – spring-summer or summer-autumn, the use of raw milk); laboratory data: using ELISA (enzymatic immunoassay), antibodies to the tick-borne encephalitis virus are detected.
Regardless of the severity of the disease, it is carried out in an infectious diseases hospital. Patients must observe strict bed rest, it will be necessary to exclude all stimuli – sound, visual, i.e. ensure complete peace. Food must be sparing and easily digestible, vitamins of groups B and C are prescribed.
Specific treatment is carried out with anti-tick gamma globulin, which is obtained from the blood of specially immunized donors. Gamma globulin is injected 6 ml intramuscularly every day for 3 days. The therapeutic effect begins 12-24 hours after the administration of gamma globulin: the body temperature drops to normal, the general condition of the patients improves, the headache decreases, and sometimes completely disappears. The earlier gamma globulin is administered (preferably in the first three days from the onset of the disease), the faster the therapeutic effect begins.
Prevent tick bites by using protective clothing. The cuffs of the sleeves should fit snugly, it is imperative to wear a hood and boots. For open areas of the body (hands, face), it is recommended to use repellents.
Raw milk is not recommended.
During the first day after the tick is sucked – emergency prophylaxis with donor immunoglobulin FSME-Bulin, which is intended for immediate specific prevention of tick-borne encephalitis (injected intramuscularly).
The most effective protection against tick-borne encephalitis is vaccination.