Tick-borne viral encephalitis in children

Kleshchevoy (spring-summer, or taiga) encephalitis is a natural focal viral disease with a predominant CNS lesion, manifested by cerebral, meningeal and focal symptoms.

ICD-10 code

• A84.0 Far Eastern viral encephalitis (Russian spring-summer encephalitis).
• A84.1 Central European tick-borne encephalitis.
• A84.8 Other tick-borne viral encephalitis (Loping's disease, disease caused by the virus Povassan).
• Tick-borne virus encephalitis, unspecified.

Epidemiology

The disease is characterized by a pronounced natural focality. In Russia, foci of tick-borne encephalitis have been recorded in the taiga regions of the Far East, Siberia, the Urals, and also in some areas of the European part of the country.

The main custodian and vector of infection is Ixodes persulcatus ticks (in the east) and I. Ricinus (in the west). In some areas, other types of ticks may also be carriers. Ticks contain the causative agent for life and transmit it to the offspring transovarially. From infected mites, the virus can be transmitted to rodents, hedgehogs, chipmunks and other animals, as well as to birds, which serve as an additional reservoir of infection.

Infection occurs when a person bites with an infected tick, while the virus enters the human blood either directly with the tick saliva or when it is squashed. It is also possible to bring the virus from the mite bite to the mucous membranes. In populated areas, cattle are involved in the epizootic process, and a person can become infected with alimentary methods when consuming infected foods, especially milk.

The disease has a pronounced spring-summer seasonality, which is associated with the maximum activity of ixodid ticks at this time of year.

Children get tick-borne encephalitis less often than adults. However, there are epidemic outbreaks of tick-borne encephalitis in rest camps, close to natural foci of infection. Children are more often ill at the age from 7 to 14 years.

Classification

There are typical and atypical forms of tick-borne encephalitis. Typical include all cases with CNS damage. To atypical - erased and subclinical forms, as well as cases that occur in a lightning speed, in which death can occur within 1-2 days, even before the appearance of the main clinical signs of the disease. The severity is determined by the extent of the CNS lesion.

Causes of tick-borne viral encephalitis

The causative agent belongs to the genus Flavivirus. The virion has a spherical shape, a diameter of 40-50 nm, contains RNA, reproduces well in many tissue cultures. From laboratory animals white mice, hamsters, monkeys, cotton rats are most sensitive to the virus. Susceptible to tick-borne encephalitis virus and many domestic animals.

What causes tick-borne viral encephalitis?

Symptoms of tick-borne viral encephalitis

The incubation period for tick-borne encephalitis is from 7 to 21 days, an average of 10-14 days. The disease begins acutely, usually with a rise in body temperature to 39-40 ° C, the appearance of severe headache, chills, fever, weakness, nausea and vomiting. From the first day of illness, hyperemia of the face, vascular injection of sclera, photophobia, pain in the eyeballs, often in the limbs, lower back. The child is braked, sleepy. Meningeal symptoms appear quickly: rigidity of the occipital muscles, positive symptoms of Kernig and Brudzinsky. On the 2-3 th day of the disease there is an encephalitic syndrome with a disturbance of consciousness from a mild sopor to a deep cerebral coma, generalized convulsions up to the development of an epileptic status, sometimes there are signs of psychomotor agitation with delirium and hallucinations. Often observed tremor of hands, twitching of the muscles of the face and limbs. Muscle tone is lowered, reflexes are depressed.

Symptoms of tick-borne viral encephalitis

Diagnosis of tick-borne viral encephalitis

Tick-borne encephalitis is diagnosed on the basis of an acute onset of the disease, severe symptoms of intoxication, early signs of diffuse or focal brain lesions, the onset of flaccid paralysis and hyperkinesia. Of decisive importance for diagnosis is the spring and summer seasonality with indication of the stay of the patient in the endemic focus of tick-borne encephalitis, the detection of a tick bite on the skin of the patient and the detection of specific IgM antibodies by the ELISA method.

Isolation of the virus from the blood and cerebrospinal fluid of patients is carried out by intracerebral infection of newborn white mice with material from the patient or in tissue culture (chicken fibroblasts).

Treatment of tick-borne viral encephalitis

Antibiotics for tick-borne encephalitis are ineffective. As an etiotropic treatment in the early periods of the disease, specific human immunoglobulin is administered from the calculation of 0.5 ml / kg per day for 2-3 days. Dehydration is carried out (25% solution of magnesium sulfate, mannitol, lasix, 20% glucose solution, etc.) and detoxification (reamberin solution, rheopolyglucin, albumin).

Treatment of tick-borne viral encephalitis

Prevention of tick-borne encephalitis

In the foci of the disease, ticks are destroyed by pollination of especially dangerous places with insecticides. The treatment of chlorophos by agricultural animals (cows, goats, sheep) that are free-range is of preventive value. Personal prevention measures include wearing special clothes and smearing the skin with scaring agents, as well as a thorough examination of clothing and body to identify ticks after visiting the forest, etc. Milk of goats and cows can be consumed only after boiling.

How to prevent tick-borne viral encephalitis?