Tick-borne encephalitis

What is tick-borne viral encephalitis?

Tick-borne viral encephalitis is an acute infectious disease characterized primarily by damage to the central nervous system. Its consequences can range from complete recovery to serious complications that can lead to disability, death, or long-term neurological impairment even after the initial infection has been overcome.

This virus belongs to the flavivirus family (Flaviviridae) and has three main types (subtypes):

1. Far Eastern.
2. Central European.
3. Two-wave viral meningoencephalitis.

The disease manifests itself in several forms:

1. Feverish (accounts for approximately 35-45% of cases).
2. Meningeal (approximately 35-45% of cases).
3. Focal form, which may include various combinations of lesions of the brain and spinal cord (approximately 1-10% of cases).

In 1-3% of those who have recovered from the disease, the disease becomes chronic. After recovery from the initial infection, some patients experience long-term neurological complications. Approximately 40% of survivors experience residual postencephalitis syndrome, which has a significant impact on health. In older people, the disease is more often severe.

The mortality rate from tick-borne viral encephalitis of the Central European type is approximately 0,7-2%, while the mortality rate from the Far Eastern form of this disease can reach 25-30%.

How can you become infected with tick-borne viral encephalitis?

Tick-borne encephalitis virus is transmitted to humans primarily through the bites of infected Ixodes ticks, such as Ixodes persulcatus and Ixodes ricinus. Infection is also possible through contact with animals such as dogs, cats, as well as people, namely through clothing, plants, branches and other objects. The virus can also enter the body through mechanical rubbing into the skin, putting pressure on the tick or scratching the bite site.

Infection is also possible through consumption of raw milk from goats, in which the virus may be present in the milk during the period of tick activity. It should be noted that there is a possibility of infection through cow's milk.

All people are always at risk of disease, regardless of age and gender. However, people working in the forest have a particularly high risk of infection, such as forestry workers, geological exploration parties, builders of roads and railways, oil and gas pipelines, power lines, as well as tourists and hunters. City dwellers are at risk of infection in suburban forests, forest parks and garden plots.

Ticks feed on a variety of animals, including agricultural (cows, sheep, goats, horses, camels), domestic (dogs, cats) and wild (rodents, hares, hedgehogs and others) species, which can serve as a temporary reservoir of the virus.

The period of activity of these ticks in nature begins in the spring and lasts until October, with the maximum number of ticks observed in the first half of summer. They mostly live in old arable lands, virgin lands, forest belts, haylofts and wet biotopes, such as coastal areas of water bodies.

What are the main symptoms of tick-borne encephalitis?

The incubation period, from the moment of infection to the first clinical manifestations, is usually about 7-12 days, but can vary from 1 to 30 days. Sometimes during this period, precursors of the disease appear, such as general malaise, weakness in the muscles of the limbs and neck, numbness of the facial skin, headache, insomnia and nausea.

The disease begins abruptly with an increase in body temperature to 38–40°C, signs of intoxication (severe weakness, fatigue, sleep disturbances) and symptoms of irritation of the membranes of the brain (nausea, vomiting, severe headache, inability to press the chin to the chest). Lethargy, vagueness of consciousness, redness of the face, neck and upper half of the body appear. The patient may feel pain in the muscles of the whole body, especially where movement disturbances will subsequently be observed, and there may also be numbness in areas of the skin or a crawling sensation, burning and other unpleasant sensations.

As the disease develops, the main symptoms appear that determine its form. Most often, tick-borne encephalitis manifests itself in the following clinical variants:

1. Feverish form, accompanied by general intoxication, but without damage to the nervous system. The outcome is usually a rapid recovery.
2. A form with damage to the membranes of the brain, which is manifested by severe headache, dizziness, nausea and vomiting, not inferior to treatment, as well as photophobia and lethargy. The body temperature remains elevated and the fever lasts 7–14 days. The prognosis is usually favorable.
3. A form with damage to the membranes and substance of the brain, accompanied by impaired movements in the limbs, paralysis, as well as impairments of vision, hearing, speech and swallowing. Sometimes seizures occur. Recovery is slow, and lifelong movement disorders often remain.
4. A form with damage to the spinal cord, manifested by movement disorders in the muscles of the neck and limbs.
5. A form with damage to nerve roots and fibers, accompanied by disturbances in sensitivity and movement in the limbs.

Tick-borne encephalitis with a two-wave course of fever is distinguished separately. The first rise in temperature passes relatively easily with symptoms of intoxication and irritation of the meninges, and the second (after a two-week break) with a complete development of the clinical picture with signs of damage to the nervous system. The prognosis, however, is usually favorable, although transition to the chronic stage is possible. Tick-borne encephalitis in children most often occurs in the form of fever or with signs of damage to the membranes of the brain. Immunity to the virus after tick-borne encephalitis usually remains lifelong.

How to protect yourself from tick-borne viral encephalitis?

The system of preventive measures includes measures to prevent tick attacks and special disease prevention. Particular attention is paid to personal prevention, which consists of careful adherence to simple and accessible measures. These measures have been applied many times and have proven their effectiveness. One of the simplest and most reliable methods of personal protection is the correct wearing of ordinary clothing, turning it into protective clothing. To do this, you need to fasten the collar and cuffs, tuck the shirt into the trousers, and the trousers into the boots.

Non-specific prophylaxis

It is important to remember that ixodid ticks can carry various infectious agents that can cause disease in humans.

Tick-borne borreliosis (Lyme disease), caused by the spirochete Borrelia burgdorferi, is widespread in the Russian Federation. The distribution area of ​​this infection is much wider than that of Tick-borne encephalitis, currently covering 72 constituent entities of the Russian Federation, including the territory of Moscow and the Moscow region. At the moment there are no specific drugs for the prevention of tick-borne borreliosis.

Given the possible danger, it is important to take precautions, choose the right clothing and use additional protective equipment, such as repellents, acaricides and others.

General Precautions

If you are in a risk area, it is important that clothing prevents the entry of ticks and at the same time facilitates their detection:

— The collar of the shirt should fit snugly to the body, preferably using a jacket with a hood.
- The shirt must be tucked into trousers and have long sleeves, and the cuffs of the sleeves must fit snugly to the body.
— Pants should be tucked into boots or shoes, and socks should have tight elastic.
— It is advisable to cover your head and neck with a scarf or cap.
— Clothing should be a light, uniform color.
— For walks in the forest, overalls of various types are best suited.
— Regular self- and mutual examinations are necessary to identify attached ticks. After walking in the forest, it is important to take off your clothes, shake them out and inspect your body.

It is not recommended to bring freshly picked plants, outerwear and other items that may contain ticks into the room. Dogs and other pets must also be examined. If possible, avoid sitting or lying on the grass. When choosing a place to camp or spend the night in the forest, it is better to prefer areas without grass vegetation or choose dry pine forests on sandy soils.

Repellents

To protect against ticks, repellents are used, so-called repellents, which are used to treat exposed skin areas.

The choice of a suitable repellent is determined, first of all, by its composition and ease of use.

In accordance with international recommendations, the greatest preference is given to repellents containing diethyltoluamide (DEET) in a concentration of 30-50%. Products containing more than 50% DEET are not required. Repellents with 20% DEET are effective for 3 hours, and those with 30% or more are effective for up to 6 hours. DEET-based repellents are safe for pregnant and breastfeeding women, as well as for children over 2 months of age. Before use, you must carefully read the instructions.

When using repellents, several rules should be followed:

— The repellent is applied only to exposed skin.
— It is necessary to use a sufficient amount of the drug (excessive amounts do not increase the protective properties).
— Do not apply repellent to cuts, wounds or irritated skin.
— After returning, it is recommended to wash the repellent off your skin with soap and water.
— When using an aerosol, do not spray it in enclosed spaces or inhale it.
— The aerosol should not be sprayed on the face: it must be sprayed onto the hands and gently smeared over the face, avoiding the eye and mouth area.
— When using repellent on children, an adult should first apply the drug to their hands and then carefully distribute it on the child; Avoid the child's eye and mouth areas and reduce the amount applied around the ears.
- You should not put repellent on your child's hands, as children often tend to put them in their mouths.
— It is recommended that adults apply repellent to a child under 10 years of age themselves, rather than entrusting this procedure to the child himself.
— Repellents should be kept out of the reach of children.

Akaritsidı

Acaricides are substances that have a paralytic effect on ticks. These drugs are used to treat clothing. Currently, products containing alphamethrin and permethrin are widely used.

Disinsection is carried out in natural foci, as well as outside them, using insecticidal preparations. This applies to places where farm animals graze, as well as areas around recreation centers. Collected ticks are destroyed either by pouring kerosene or by burning.

Specific prophylaxis

As of my last update, there are several vaccines available that are effective against different types of viral encephalitis. Some of these include vaccines against tick-borne encephalitis, Japanese encephalitis and others. Vaccines against tick-borne encephalitis, such as Encepur and TicoVac, have been found effective and are widely used in Russia and Europe. For specific information about the currently most effective vaccines, it is best to consult medical research and recommendations from local health organizations.

What should I do if bitten by a tick?

If you are bitten by a tick, you should remove it immediately. To remove the tick, use tweezers or a special tick remover. When removing, try not to squeeze the tick's body to avoid transmitting possible infections. After removal, treat the bitten area with an antiseptic. Pay attention to symptoms of tick-borne illnesses, such as fever, rash, headache, muscle weakness, and others. If suspicious symptoms appear, consult a doctor.

Recommendations for removing ticks yourself

You should use tweezers or gauze-wrapped fingers to grasp the tick as close to its mouthparts as possible. When extracting, turning the parasite around its axis, it is necessary to hold it perpendicular to the surface of the bite and make light movements. If the head of the tick comes off, it should be removed with a sterile needle or left until it is removed naturally. It is important to avoid squeezing the tick's body so as not to cause the contents to leak into the wound. After removing the tick, it is recommended to treat the bite site with tincture of iodine or alcohol. You should not use your teeth to remove a tick to avoid possible infection through the mouth. Be sure to wash your hands thoroughly with soap after removing a tick to prevent possible infection from entering through microcracks in the skin.

Diagnosis of tick-borne encephalitis

To diagnose tick-borne encephalitis, it is necessary to confirm the fact of tick suction and establish the endemicity of the area for tick-borne encephalitis. The doctor conducts a thorough examination of the patient, including a complete neurological analysis, in order to exclude other infectious and non-infectious diseases that are accompanied by similar symptoms.

Laboratory diagnosis of tick-borne encephalitis includes determining the titer of IgM and IgG antibodies to the tick-borne encephalitis virus over time.

Which doctor should I contact if I suspect tick-borne encephalitis?

If you suspect tick-borne encephalitis, you should contact a neurologist or infectious disease specialist for consultation and further treatment.

Treatment, complications and prevention of tick-borne encephalitis

Treatment of complications caused by tick-borne encephalitis is usually carried out taking into account the symptoms and severity of the patient's condition. This may include the use of antivirals, antibiotics, and medications to reduce inflammation and relieve symptoms. Rehabilitation techniques and supportive care may also be used to restore body function.

Prevention of tick-borne encephalitis includes the use of repellents, protective clothing, acaricides, and vaccinations. Vaccination is considered effective in preventing the disease in persons living in or traveling to endemic regions. In addition, it is important to avoid contact with ticks, carefully inspect your body after walking in the forest, and follow the preventive measures described in recommendations for preventing tick bites.