What is Tick-borne Encephalitis in Children?
Tick-borne encephalitis is also called spring-summer or taiga. This is a natural focal viral disease (the causative agent of which circulates among animals), in which there is a defeat of the central nervous system, and in which cerebral, meningeal and focal symptoms are manifested.
Tick-borne encephalitis in children is:
- tick-borne encephalitis
- Far Eastern viral encephalitis (also called Russian spring-summer encephalitis)
- tick-borne viral encephalitis, unspecified
- another tick-borne viral encephalitis.
The disease is called natural focal when the pathogen is found among animals and insects and spreads by them. Tick-borne encephalitis refers to such diseases. In Russia, the foci of this disease are located in the taiga in the Far East, Siberia, the Urals, and in some areas of the European part of the country.
Ixodid ticks are the main guardians and carriers of infection. On Vvostok it is Ixodes persulcatus, and in the west it is Ixodes ricirtus. In some parts of the disease, other tick species can cause the disease. These insects contain the causative agent of the disease for life, lay infected eggs, from which then infected ticks appear (transovarial transmission of infection).
Ticks in the wild infect rodents, hedgehogs, chipmunks and other animals and birds. Infected animals from that moment can also spread the infection. A person becomes infected by being bitten by an infected tick. Together with tick saliva, the virus enters the baby’s blood (and the likelihood of infection increases when the infectious tick is crushed). The virus can be brought from the bite to the mucosa.
In some areas, cattle may participate in the infection chain, whose meat and milk are then consumed by the person along with the infection.
An increase in the incidence is observed in spring and summer, as It is at these times of the year that ixodid ticks are most active. The incidence of tick-borne encephalitis among children is lower than among adults, but still there. There are also epidemics in rest camps, which are located next to tick habitats (forests). Children 7-14 years old are most susceptible to the disease among children.
Causes of Tick-borne Encephalitis in Children
The causative agent of the disease belongs to the genus flaviviruses. The spherical virion has a diameter of 40 to 50 nm. The virus contains RNA and can multiply in many tissue cultures. Among animals tested in laboratories, hamsters, white mice, monkeys and cotton rats are most susceptible to the virus.
Tick-borne encephalitis can infect pets. The virus can be killed with ordinary disinfectants, by raising the temperature of the environment. The virus in its dried form can retain its properties for months and even years.
Pathogenesis during Tick-borne Encephalitis in Children
The primary locations of the virus are the skin, subcutaneous tissue, and the gastrointestinal tract. With the help of lymph and blood, the virus spreads throughout the body, even entering the central nervous system. There, it causes damage to the gray matter of the brain and spinal cord. Hard and soft meninges are also affected. Intoxication is manifested, damage to the visceral organs, for example, the adrenal glands, spleen, etc. occurs. The cardiovascular system that the virus can affect is also at risk.
The virus causes the greatest morphological changes in the central nervous system. Puffiness and plethora of the soft and hard shells of the brain are recorded. In the section, the substance of the brain and spinal cord is flabby, swollen, with point hemorrhages. Histological examination allows you to determine disseminated perivascular infiltrates, degenerative-dystrophic changes in nerve cells (even complete necrosis is likely), etc.
Significant changes occur in the brain stem, the anterior horns of the spinal cord, the hypothalamic region, the optic tubercle and in the cerebellum.
Inflammation can also be in other organs of the child.
Symptoms of Tick-borne Encephalitis in Children
The incubation period for tick-borne encephalitis in children lasts from 1 week to 3 weeks. On average, the period is from 10 to 14 days. The disease has an acute onset, often the temperature “jumps” to 39-40 ˚С. The child complains of a severe headache. Sometimes there are prodromal phenomena (just before the onset of the manifestation of the disease) – general weakness, disturbed sleep rhythm and headache.
From the first day the patient’s face turns red (hyperemia), the scleral vessels are red (vascular injection). Photophobia begins. Eyeballs, limbs (not always), lower back may hurt. Lethargy and drowsiness appear. Signs of irritation of the meninges soon appear; stiff neck muscles, positive symptoms of Kernig and Brudzinsky. It is worth noting that Brudzinsky’s symptoms are characteristic not only of tick-borne encephalitis. This group of symptoms is divided into: upper, middle, lower, buccal. As for Kernig’s symptom, it is also characteristic not only of tick-borne encephalitis, in general, it indicates irritation of the meninges.
On the 2nd or 3rd day of the disease, encephalitic syndrome with impaired consciousness appears. In mild cases, it can manifest itself as mild stupor (depression of consciousness with the loss of voluntary and preservation of reflex activity). In severe cases, encephalitic syndrome manifests itself as generalized seizures up to the development of status epilepticus. There are signs of psychomotor agitation with delusions and hallucinations. In frequent cases, there is a tremor of the hands, twitching of the muscles of the face and limbs. A tremor of the hands means rapid muscle contractions, which outwardly resembles a trembling of the limbs. A decrease in muscle tone and inhibition of reflexes are recorded.
Against the background of the manifestation of symptoms of diffuse encephalitis, some sick children may show signs of focality.
When the white matter of the brain is damaged, there is a likelihood of spastic paresis of the limbs. Paresis refers to a weakening of a muscle or muscle group in the limbs. Often, hemiparesis is accompanied by central paresis of the facial and hypoglossal nerves on the affected side. Focal lesions can be manifested by various hyperkinesis resulting from irritation of the white matter of one of the cerebral hemispheres by rapidly forming scar tissue. Hyperkinesis is often manifested by clonic convulsions of local muscle groups.
When the virus infects the gray matter of the spinal cord, poliomyelitis syndrome with flaccid paralysis occurs. Most often, paresis of the cervicobrachial muscles and arm muscles appears. If a bilateral lesion occurs, the child’s head hangs down, movements in the shoulders and arms are limited. At 2-3 weeks of the disease, muscle atrophy is found. Paresis of the legs is quite rare. During the recovery period, the development of contractures, curvature of the trunk, deformation of the affected arms and legs are possible.
Cerebrospinal fluid with tick-borne encephalitis flows out under increased pressure, transparent, with moderate lymphocytic cytosis. The amount of protein is initially normal, with recovery slightly increased.
At the height of the manifestation of symptoms in the blood, moderate leukocytosis with a shift to the left to stab, increased ESR is observed. With the manifestation of pastic paralysis, changes in the blood may not be observed.
Tick-borne encephalitis can be typical or atypical. Typical cases are characterized by damage to the central nervous system. Atypical forms include erased and sublinic, as well as cases of fulminant disease, which are fatal after only 1-2 days, while the symptoms have not yet appeared. The severity of the disease is determined by the degree of damage to the central nervous system.
The period of fever in this disease lasts from 5 to 10 days, rarely 3-4 weeks or more.
Death from illness can occur in the first 3 days of illness. It is caused by paralysis of the respiratory and vasomotor centers and the phenomena of general toxicosis with edema and swelling of the brain substance.
If the course of the disease is favorable, the patient’s condition becomes better when the body temperature drops, over time, the symptoms of damage to the nervous system gradually disappear. The course of the disease can be long, gradually progressive, and recurrent. Persistent mental disorders, paralysis, contractures, deformities, etc. are also possible.
The clinical type of tick-borne encephalitis is the so-called two-wave viral meningoencephalitis, also called milk fever. This disease is contracted through food if the milk consumed has been infected with ticks. But the route of infection through the bites of Ixodes ricinus is not excluded. In this case, whole families can become infected. Cases were recorded both in Russia and in Belarus, Sweden, Norway, Czechoslovakia and Finland.
If the infection occurred through milk, the disease manifests itself only 4-5 days. If the infection is provoked by a tick bite, the incubation period lasts from 4 to 20 days. Fever in most patients occurs in two successive waves. The first wave lasts 2-10 days, the second wave lasts about a week. Less often, there is only one wave, the duration of which is 5-30 days.
The first febrile wave is accompanied by such symptoms as headaches and dizziness, sleep disturbances, lack or loss of appetite, reddening of the vessels of the skin of the face, injection (overflow of blood) of the vessels of the sclera and conjunctiva. There is a possibility of meningeal symptoms. The condition becomes better when the body temperature of the sick child drops. But lethargy, poor appetite and headache remain. After 5-8 days, the temperature starts to rise again (second wave). Symptoms recur. Headaches are severe. Vomiting can be repeated. When the eyeballs move, pain occurs.
Dull heart sounds are heard. Blood pressure decreases. There are meningeal symptoms, pain in the march of the nerve trunks, hyperesthesia, symptoms of tension, decreased muscle tone, a sharp decrease in tendon reflexes, sometimes symptoms of oral automatism, tremors, nystagmus, dysarthria. The patient’s gait is unstable.
The course of the disease is favorable. The functions of the nervous system are restored to 100% in the 2-3rd month.
Diagnosis of Tick-borne Encephalitis in Children
The diagnosis of tick-borne encephalitis is carried out according to such signs as an acute onset of the disease, severe symptoms of intoxication, early signs of diffuse or focal brain damage, the appearance of flaccid paralysis and hyperkinesis. The spring-summer season gives a clue to the diagnosis, especially if the patient has been in the habitat of ticks for some time.
Also, diagnostics is carried out by detecting a tick bite on the child’s skin. Helps to diagnose the presence of specific antibodies of the IgM class (using 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 Encephalitis in Children
Antibiotics are ineffective. As an etiotropic treatment in the early periods of the disease, a specific human immunoglobulin against cellular encephalitis is administered. The dose is calculated as follows: 0.5 ml per 1 kg of the patient’s body per day (course 2-3 days). Dehydration is carried out using a 25% solution of magnesium sulfate, mannitol, lasix, 20% glucose solution, etc. For detoxification, drugs such as rheopolyglucin and albumin are indicated.
Doctors can prescribe symptomatic therapy. For the treatment of severe cases, glucocorticosteroids are used in doses according to the child’s age for 5-10 days. If the patient shows breathing disorders, the patient is transferred to artificial ventilation. The recovery period after the recovery takes place with the appointment of massage, gymnastics, physiotherapy procedures. Doctors also advise treatment in resorts.
Prevention of Tick-borne Encephalitis in Children
If an outbreak is found in the wild, the area is sprayed with insecticides. For the prevention of s / g animals, chlorophos treatment is also used (relevant for cows, goats, sheep, etc.).
Personal prophylaxis consists of wearing protective clothing and lubricating the skin with a tick-repellent agent. After walking in forests and parks in warm seasons, you should carefully examine your clothes and body, especially sensitive parts of it, to identify ticks. Milk (cow and goat) is eaten after boiling to kill the infection.
In the foci of infection, if there is an epidemiological indication, active immunization is used. And also – for persons dealing with viruses. The following vaccines are used:
- enceVir – vaccine of tick-borne encephalitis cultural purified concentrated inactivated liquid of the day of intramuscular injection by FSUE NPO Microgen (Russia);
- tick-borne encephalitis vaccine cultured purified concentrated inactivated dry (Russia);
- children’s encepur of the Kyron Bering company (Germany);
- adult encepur of Kairoy Bering (Germany);
- FSME – immunization from Baxter AG (Austria).
The vaccine is administered two times, the interval between vaccinations is from 1 to 3 months. Revaccination is performed after 9-12 months. Also for prevention, human immunoglobulin against tick-borne encephalitis is used. For the purpose of emergency post-exposure prophylaxis of tick-borne encephalitis, an immunomodulator with antiviral activity, anaferon for children, can be used. Children under the age of 12 should take 1 tablet 3 r. per day, and children from 12 years old take 2 tablets 3 r. per day for 21 days (conventionally accepted value of the duration of the incubation period).
Anaferon for children is also used in the complex treatment of tick-borne encephalitis starting from the period of early convalescence to potentiate the antiviral action and prevent the activation of the persistent virus. The drug is prescribed for 1 month with a febrile form and up to 3 months with a meningeal and focal form. Children under 12 years old – 1 tablet 3 times a day, children over 12 years old – 2 tablets 3 times a day.