Tick-borne encephalitis is an acute disease of viral etiology that develops with the bites of infected ixodid ticks and is characterized by the appearance of general intoxication, neurological symptoms and a clinic of encephalitis.
Causes of the disease
The disease develops as a result of the ingestion of tick-borne encephalitis virus, which refers to RNA viruses. The causative agent is unstable in the environment and quickly dies under the influence of sunlight, heat or exposure to disinfectant solutions. There are several types of virus depending on the territorial distribution. Tick-borne encephalitis caused by a virus spread in the Far East, is considered the most severe in its course.
The disease develops when a person bites a virus-infected tick. That, in turn, is only a carrier of the virus, which enters the tick when it bites infected animals, often small rodents. There is a so-called "cycle" of the virus in nature: a sick animal - a tick - an animal. In Russia, the tick is widespread everywhere, especially in the middle lane, the Urals, Siberia and the Far East. Not all ticks are carriers of the virus. The number of infected insects in different regions is different and amounts to several percent of the entire population. The peak incidence occurs in early spring and early summer. At this time, ticks are most active, although the possibility of infection persists throughout the entire warm period of the year.
The virus enters the human body with tick saliva directly during a bite. The causative agent can penetrate through minor scratches and damage to the skin if a person crushed a tick and with unwashed hands brought the virus into the wound.
Less commonly, the encephalitis virus can enter the body when consuming raw, unpasteurized milk from large and small horned animals.
Once in the body, the virus replicates in macrophages. Further, with the flow of blood, it penetrates the lymph nodes, liver and other organs, where its reproduction begins. Then it enters the cells of the spinal cord and brain, after which the clinic characteristic of the disease develops.
Signs of tick-borne encephalitis
The asymptomatic period when infected by a tick bite is about one to two weeks, and when infected through milk, it is about a week.
The onset of the disease is characterized by the appearance of malaise, loss of appetite, headache and dyspepsia, pain in the muscles and joints. Body temperature rises. Very often, these symptoms are mistaken for a viral or bacterial infection. At this, the manifestations of the disease can end, but in a third of patients after about a week the next, second phase of the disease occurs with a repeated increase in temperature and the appearance of neurological symptoms. Perhaps the development of encephalitis, the appearance of pathological neurological symptoms, impaired consciousness, the development of paralysis.
Diagnostics
Tick-borne encephalitis is diagnosed on the basis of characteristic complaints and the clinical picture of the disease. The patient may indicate a recent tick bite. In blood tests at the beginning of the disease, you can see a decrease in white blood cells, a slight increase in liver enzymes. The most accurate way to make a diagnosis is the immunological method. Two sera are taken at different time intervals in which the growth of specific antibodies is observed.
Tick-borne encephalitis is also diagnosed using the biological method, in which the extracted tick is examined for the carriage of the virus.
To confirm the diagnosis with an already developed lesion of the nervous system, virus isolation in the cerebrospinal fluid and blood is used.
Treatment measures for encephalitis
With uncomplicated encephalitis, symptomatic therapy is performed, antipyretic drugs, multivitamins are prescribed, a specific immunoglobulin is administered according to the scheme. The patient must observe rest and strict bed rest. In severe illness, treatment is carried out in the neurology department.
Prevention
In order to prevent the disease, it is advisable to refrain from going to nature during the period of maximum tick activity. You need to carefully inspect clothing and skin after visiting suburban places. With a sucking tick, you need to carefully remove it, trying to ensure that its jaws do not remain on the skin. An extracted tick is referred to a virological examination. At the trauma center, preventive prevention of the disease is carried out. But a more reliable method of prevention today is a tick-borne encephalitis vaccine.