Tick-borne Encephalitis - Causes, Symptoms And Treatment

2024 Author: Josephine Shorter | [email protected]. Last modified: 2024-01-07 17:49

Symptoms and treatment of tick-borne encephalitis

It is difficult to imagine that an ordinary trip to nature can turn into a real tragedy. This is exactly what happens if a person has been bitten by a tick that carries tick-borne encephalitis. In this case, the victim receives a severe lesion of the central nervous system, which is dangerous for its complications and a high risk of death.

Content:

• What is tick-borne encephalitis?
• Tick-borne encephalitis symptoms
• Who is the causative agent of tick-borne encephalitis?
• Tick-borne encephalitis forms
• Diagnostics
• Vaccination scheme
• Tick-borne encephalitis treatment
• Prevention

What is tick-borne encephalitis?

Synonyms for this viral disease are meningoencephalitis, viral encephalitis. The infection is transmitted through blood-sucking insects and is therefore classified as a vector-borne infection. The affected area of the viral infection is the brain and spinal cord.

The virus carrier is the ixodid taiga and European ticks, no more than 5% of the population. It feeds on the blood of humans and warm-blooded animals. The tick bites through the skin and injects saliva, which contains virus particles, into the tissue. For several days, the females of the tick are able to remain on the body of their temporary host, the males disappear immediately after saturation. A patient infected with the encephalitis virus is not a source of infection, the disease is not transmitted by airborne droplets. The transplacental route of infection is very rare, when an infected pregnant woman transmits the virus to the fetus through the placenta.

In addition to humans, wild animals, goats, and cows suffer from ticks. Once in the bloodstream, the virus spreads through the nervous and circulatory system. If dairy products obtained from a sick animal have not undergone heat treatment, they become a source of human infection with tick-borne encephalitis.

Season of greatest tick activity:

• Spring - May, June;
• Summer - August, September.

Most often in our country, ixodid ticks are found in the Novgorod, Leningrad, Pskov, Samara, Nizhny Novgorod, Kirov, Tyumen, Chelyabinsk regions. Potentially dangerous territories - Udmurtia, Bashkortostan, Perm Territory, Tatarstan, Siberian Federal District.

Up to 5-6 thousand cases of tick-borne encephalitis are recorded in Russia annually. Approximately 25-40% of all cases of Far Eastern tick infection are fatal. The Western virus leads to this resolution of the disease in only 1% of cases. The world's most dangerous regions in this regard are Mongolia, China, and some areas in the countries of Scandinavia and Eastern Europe.

Tick-borne encephalitis symptoms

The emergence of acute symptoms of the disease is preceded by the incubation period, when viruses trapped in the subcutaneous tissue, in the circulatory, nervous and lymphatic systems, actively multiply. The duration of the incubation period for infection through the skin is 7-21 days, through the intestines - 3-6 days. A fulminant form of encephalitis manifests itself within a day, a protracted form - after 25-30 days.

There are 4 stages of the course of the disease:

• The incubation period when symptoms of the disease are not observed.
• Penetration of the virus into the central nervous system, the appearance of symptoms of intoxication.
• The appearance of neurological symptoms of damage to the spinal cord and brain.
• Recovery, the emergence of immunity to tick-borne encephalitis.

The first symptoms of the disease resemble those of the flu or a respiratory viral infection:

• Hyperthermia up to 39-40 ° C, fever, chills;
• Photophobia, aches in the eyeballs;
• Severe pain and aches in the lower back and limbs;
• Weakness;
• Nausea and vomiting;
• Confusion of consciousness, lethargy;
• Drowsiness.

When the virus spreads in the substance of the brain, disturbances in the activity of the nervous system are noted:

• Decreased skin sensitivity, feeling of "goose bumps" on it;
• Violations of the movement of facial muscles, arbitrary movement of the limbs;
• Seizures;
• Headache;
• Weakness of the muscles of the neck and limbs;
• Ptosis of the upper eyelid (ptosis);
• Lack of movement of the eyeballs (ophthalmoplegia);
• Numbness of the face and neck;
• Vomiting, single convulsions (more common in children);
• Redness of the face and neck;
• Dilated blood vessels, clearly visible in the whites of the eyes.

The further course of encephalitis depends on the form of its course. After recovery, the patient may feel weakness, excessive sweating, tachycardia, and impaired appetite for 3-5 weeks.

Who is the causative agent of tick-borne encephalitis?

The disease is caused by a PHK-containing arbovirus from the genus Flavivirus. The virus is a ball with protrusions on the surface. Due to its very small size (40-50 nm), it easily penetrates cell barriers. The tick-borne encephalitis virus is 2 times less than the influenza virus, 4 times less than the measles virus. It has several varieties, differing in the place of preferential localization:

• Far East virus - causes the greatest number of deaths and severe forms of encephalitis, since the virus is the most virulent;
• Western virus - the forms of encephalitis caused by this virus are not severe, they proceed in a two-wave mode;
• The Siberian virus is less virulent, but quite dangerous for humans.

The area of introduction of the arbovirus is the motor structures of the nervous system. Its distinctive feature is that the virus can stay inside the human body for a long time without provoking an immune response. It is weakly resistant to boiling, disinfectants, and ultraviolet rays. Bright sunlight, boiling, heating in any other way destroy the pathogen of tick-borne encephalitis in 2 minutes. Low temperatures are not able to reduce the viability of the arbovirus; it remains in frozen food for up to 2 months.

Tick-borne encephalitis forms

Currently, there are several forms of the course of the disease, which have a characteristic clinical picture.

Febrile form

The virus in this form of encephalitis does not penetrate into the membranes of the brain, circulating through the circulatory system. The onset of the disease is manifested by flu-like symptoms - fever, headache, nausea and vomiting. The manifestations of damage to the nervous system are insignificant - the muscles of the limbs and lower back ache.

The acute period lasts 2-10 days, then the manifestations of encephalitis subside. The disease can return during the so-called "second wave", when a febrile state occurs within a few days. Even after recovery, confirmed by the results of laboratory diagnostics, the patient feels weak, loss of appetite, and increased heart rate.

Meningeal form

More often than others, it affects patients with encephalitis, characterized by damage to the membranes of the brain and spinal cord. The characteristic manifestations of the disease occur on day 3-4, and manifest themselves within the next two weeks.

Meningeal syndrome manifestations:

• Severe headache, not amenable to the action of analgesics;
• Hypersensitivity of the skin, when any touch is felt like severe pain;
• Nausea and vomiting;
• Tension of the occipital muscles, leading to throwing the head back;
• Kernig's symptom is the inability to straighten the leg bent at the knee;
• Brudzinsky's symptom is reflex flexion of the knees when pressing on the patient's pubis and the forced tilt of his head forward.

Within 2 months after the end of the acute period, the patient experiences unmotivated mood swings, intolerance to bright light and loud sounds, weakness.

Poliomyelitis form

At the onset of the disease, when the infection affects the cells of the spinal cord, the patient feels weak, overworked.

Then movement disorders come to the fore:

• Numbness of skin areas of the extremities;
• The inability to arbitrarily control facial muscles, muscles of the limbs;
• Pain in the arms, shoulder girdle, and neck;
• Reduction of muscles in volume;
• Inability to hold your head.

Additionally, signs of other forms of encephalitis appear.

Polyradiculoneuritic form

With this type of encephalitis, the peripheral nervous system is affected.

Damage symptoms:

• Pain and tingling all over the body, creeping sensation;
• Wasserman syndrome (pain in the hip when lifting the leg);
• Lasegue syndrome (pain along the sciatic nerve when lifting a straight leg up);
• Landry's ascending paralysis, starting in the legs and covering all muscles up to the muscles of the face, oral cavity, respiratory muscles.

Ascending paralysis can lead to suffocation.

Meningoencephalitic form

The most severe form of encephalitis and an unclear prognosis and the presence of a large number of complications. Distinguish between diffuse and focal forms of meningoencephalitis. The disease develops so sharply that the patient can even remember the hour when his condition deteriorated sharply. The debut of the disease begins with a rise in temperature, the appearance of seizures and vomiting.

In this form of infection, the virus infects the medulla of all parts of the central nervous system. The patient has hallucinations, delusional state, distortion of the perception of time, space.

Symptoms depending on the location of the virus:

• Brain stem damage - impaired cardiac activity and breathing;
• The defeat of the cerebellum - tremor of the limbs, imbalance;
• Spinal cord injury - decreased muscle tone, paralysis and paresis of the muscles of the shoulders, chest;
• The defeat of the roots of the spinal cord - symptoms of radiculitis, a violation of skin sensitivity.

In addition, the patient's facial muscles and muscles of the oral cavity and pharynx are affected, which causes slurred speech, problems with swallowing, strabismus, and impaired facial expressions.

With a progressive type of meningoencephalitis, the manifestations of the disease do not recede for several months and even years after the acute period of the disease.

Diagnostics

The main parameters that specialists are guided by are the clinical characteristics of encephalitis, laboratory data, epidemiological information.

• The clinical picture of encephalitis. When examining a patient, a neurologist objectively evaluates signs of damage to the patient's systems and organs. It takes into account the complaints of the person suffering from encephalitis, the timing of the initial symptoms, the sequence of their appearance.
• Laboratory research data. To establish a diagnosis, a blood and cerebrospinal fluid test using a polymerase chain reaction (PCR) is used. An additional method is the determination of the antibody titer using serological methods, blood serum tests. This analysis is taken at intervals of two weeks. The level of antibodies in the sample, the dynamics of their change, depending on the time interval since the onset of the disease are assessed.
• Epidemiological information. To narrow the circle of people presumably sick with encephalitis, they analyze information about the patient's place of residence, the season during which the infection occurred, about what products the patient consumed, about his professional activities.

Vaccination scheme

Vaccination against tick-borne encephalitis is an effective measure to prevent this disease.

Vaccine administration method:

• Passive immunization - carried out with a tick bite by introducing immunoglobulin to those who have not been vaccinated before;
• Active immunization - carrying out vaccinations 1 month before the season of tick activity in residents of encephalitis-endemic areas.

Vaccinations can only be done after a medical examination. There is a traditional and emergency vaccination schedule.

Vaccination schedule:

• The first vaccination is carried out at the time prescribed by the doctor.
• The second - after 1-3 months after the first.
• The third - after 9-12 months.

If you have not received the third vaccination, you can count on protection within one year after vaccination. The completed course guarantees a stable immune response for 3 years.

Emergency vaccination option:

• The first vaccination at the invitation of a medical institution.
• The second is 2 weeks after the first.
• The third - after 9-12 months.

An emergency vaccination option is resorted to in case of an unforeseen travel, business trip to endemic areas.

Contraindications for vaccination against encephalitis:

• Allergy to vaccine and chicken egg protein;
• The use of medicines;
• Cardiovascular insufficiency;
• Rheumatism;
• Tuberculosis;
• Diabetes;
• History of stroke and heart attack;
• Acute form of somatic and viral diseases;
• Pregnancy and lactation - with caution, only at high risk.

In Russia, a cultured purified vaccine against encephalitis is used, as well as Encevir, Encepur for children and adults, and FSME-immun.

Tick-borne encephalitis treatment

Since the patient does not pose a danger to others, his treatment takes place not in the infectious diseases department, but in the neurological department of the hospital under bed rest. The main drug treatment in the early stages of the disease is the administration of a specific immunoglobulin. Additionally, antiviral therapy is carried out.

The drugs used:

• Medicines containing interferon (Roferon, Intron A, Ribavirin, Ribonuclease);
• Interferon inductors (Cycloferon, Amiksin, Neovir);
• Preparations for removing toxins from the body;
• Antipyretic drugs;
• Anti-inflammatory drugs.

With therapy carried out in the late stages of tick-borne encephalitis, symptoms that threaten the patient's life are stopped.

Methods of treatment for damage to the nervous system and drugs used:

• Oxygen mask application;
• Artificial lung ventilation;
• Drugs that reduce intracranial pressure;
• Antipsychotics;
• Medicines that stop the effects of oxygen starvation;
• Preparations for improving the trophism of nerve tissues;
• Medicines to restore blood microcirculation.

The duration of the course of treatment takes 3 to 5 weeks. After discharge, the patient is put on dispensary registration for 1-3 years. He should be examined at intervals of 3-6 months. With the transition of the disease into a chronic form, recurrence of the infection is possible against the background of an apparent complete recovery. They occur in the first six months after the end of the course of treatment.

The prognosis of his recovery and possible complications depend on the form of encephalitis suffered by the patient.

Possible complications of infection:

• Epilepsy;
• Edema of the brain, leading to coma and death;
• Paralysis of the muscles of the neck and limbs;
• Violations of speech, the act of swallowing;
• Strabismus.

Muscle atrophy resulting from the transferred tick-borne encephalitis leads the patient to disability.

Prevention

All residents of encephalitis-endemic areas should know how to take precautionary measures during the tick season when traveling in forest park areas.

Preventive measures:

• Wearing clothes with long sleeves and trousers that cover the maximum possible area of the body;
• Putting on hats;
• Thorough examination of the body and clothing after walking to look for mites, combing the hair with a fine comb (it is better if the clothing is light in color);
• Removing a tick in a medical facility;
• Active use of repellents before walking in the forest;
• Prohibition of picking branches;
• Laying a path to bypass low-growing bushes.

It is imperative to boil homemade milk, heat dairy products purchased from unfamiliar manufacturers.

Timely vaccination, minimization of contact with ticks, contacting a doctor with a tick bite and the first signs of encephalitis will help to avoid serious complications of this disease.

Author of the article: Alekseeva Maria Yurievna | Therapist

Education: From 2010 to 2016 Practitioner of the therapeutic hospital of the central medical-sanitary unit No. 21, city of elektrostal. Since 2016 she has been working in the diagnostic center No. 3.