Two-wave viral meningoencephalitis is a form of tick-borne encephalitis, the peculiarity of which is the presence of two periods of clinical manifestations of the disease, separated from each other by a short remission. In the first period, diseaseoccurs with general cerebral and general infectious symptoms, in the second – with focal symptoms of organic damage to the central nervous system, neuritis and radiculitis. The basis for the diagnosis is the epidemiological history of the disease, its typical clinical picture, the data of cerebrospinal fluid studies, the results of MRI and CT. Treatment includes specific and non-specific antiviral therapy, detoxification, symptomatic, nootropic and vascular agents.
ICD 10
A84 Tick-borne viral encephalitis
General information
Two-wave viral meningoencephalitis is a naturally focal infectious disease of viral etiology. Like tick-borne encephalitis, disease is carried by ixodic ticks and has a spring-summer seasonality. However, due to the pronounced features of its clinical course, since 1952, two-wave viral meningoencephalitis has been considered a separate nosological unit in neurology. People aged 20 to 40 years who are engaged in work in the forest (workers of forestry enterprises, geologists, hunters, road builders, tourists) are most susceptible to morbidity.
Etiology
The cause is a virus that has a tropicity to the glial tissues of the brain. At the same time, the neurons of the brain in most cases remain intact, which causes the transient nature of pathological changes and a favorable prognosis of the disease, distinguishing it from encephalitis of another genesis. According to its immunological properties, the virus that causes two-wave viral meningoencephalitis is close to the causative agent of tick-borne encephalitis. Once in the human body, it first multiplies in parenchymal organs, and then penetrates into the brain and accumulates there.
Infection with the virus is possible in 2 ways. The transmissible path of transmission of infection is realized by the bite of an ixodic tick, which is a reservoir and carrier of the pathogen. The second way is alimentary. In this case, infection occurs when eating raw milk obtained from a goat infected with a tick bite. When infected with a transmissible pathway, two-wave viral meningoencephalitis occurs as a separate case of the disease and has a longer incubation period (from 12 to 20 days). With alimentary infection, two-wave viral meningoencephalitis affects several people at once and proceeds with an incubation period of 4 to 7 days.
Symptoms
The clinical picture of two-wave viral meningoencephalitis consists of clearly expressed two acute periods accompanied by a significant rise in body temperature. Usually, two-wave viral meningoencephalitis begins suddenly without any prodromal symptoms. Characterized by high (up to 39 ° C) body temperature, chills, malaise, arthralgia, myalgia, headache, sleep disorders, dizziness, nausea and vomiting. Mild meningeal symptoms may be observed. The duration of the first period of two-wave viral meningoencephalitis is no more than a week. Then the body temperature drops and remains normal, less often — subfebrile, for 5-7 days. During this period, almost all the initial symptoms of the disease disappear.
After a short remission, body temperature rises again and general well-being worsens. In the second period of exacerbation, two-wave viral meningoencephalitis is characterized by a more severe clinical picture associated with organic brain damage typical of encephalitis. In this period, focal symptoms may be observed: central paresis of the extremities, a decrease in superficial and deep sensitivity, vestibular ataxia, cerebellar syndrome; mental disorders and epileptic seizures are possible. Unlike tick-borne encephalitis, with two-wave viral meningoencephalitis, these symptoms are usually poorly expressed, and such severe disorders as bulbar syndrome are extremely rare. Usually peripheral nerve lesions come to the fore: neuritis and sciatica.
Diagnostics
It is very difficult to diagnose two-wave viral meningoencephalitis in the first period of the disease, when its clinical picture is mainly represented by general infectious manifestations characteristic of other acute infectious diseases (ARVI, influenza, brucellosis, measles, scarlet fever, yersiniosis, leptospirosis, etc.), as well as fever of unknown genesis. Epidemiological data (tick bite, consumption of raw goat’s milk) and the second wave of clinical manifestations characterizing two-wave viral meningoencephalitis allow to make a more accurate diagnosis.
For diagnostic purposes, a patient with two-wave viral meningoencephalitis should be examined by a therapist, a neurologist and an infectious disease specialist. Lumbar puncture is indicated for subsequent physico-chemical, microscopic and virological examination of cerebrospinal fluid. Typical for two-wave viral meningoencephalitis is a moderate increase in the number of cellular elements of the cerebrospinal fluid mainly due to lymphocytes (lymphocytic pleocytosis). Such a picture of the cerebrospinal fluid makes it possible to exclude purulent meningitis and testifies in favor of the viral etiology of the disease.
Two-wave viral meningoencephalitis must be differentiated from encephalitis and meningitis of a different etiology, from a brain abscess, suppuration of a cyst or intracerebral hematoma. To do this, the list of instrumental examinations of the patient includes an MRI of the brain, and if there are contraindications to its conduct, a CT scan of the brain.
Treatment
During the period of fever and pronounced clinical manifestations with two-wave viral meningoencephalitis, it is necessary to observe bed rest, adhere to a gentle and fortified diet. To combat the general intoxication of the body in the initial period of the disease, detoxification therapy is carried out. From the first days of two-wave viral meningoencephalitis, etiotropic antiviral treatment is prescribed. It is similar to the treatment used in the case of tick-borne encephalitis, and includes specific donor gamma globulin, interferon and ribonuclease preparations.
With symptoms of hydrocephalus and increased intracranial pressure, the patient is undergoing dehydration therapy. Nootropics (gamma-aminobutyric acid, glycine, ginkgo biloba preparations, piracetam), B vitamins and vascular preparations (pentoxifylline, vinpocetine) are actively used to eliminate neurological disorders as soon as possible.
Forecast
Usually, two-wave viral meningoencephalitis has a favorable course and ends with a complete recovery of patients. Fatal outcomes of the disease or its transition to a chronic form have not been observed in medical practice. Usually, 100% regression of neurological symptoms occurs against the background of treatment. Asthenic syndrome may persist for some time.
Prevention
Preventive measures to disease are in many ways similar to those in spring-summer tick-borne encephalitis. Non-specific preventive measures in areas with an increased risk of infection include: the destruction of ticks, the use of protective clothing and repellents when in the forest, the refusal to use unboiled milk. While staying in an endemic focus during the period of tick activity, it is necessary to carefully inspect clothing and skin. If a tick is detected, it should be carefully and completely removed, and the bite site should be treated with iodine. The removed tick must be burned.
Specific prevention is carried out with a vaccine against tick-borne encephalitis. Immunity is formed 2 weeks after the double administration of the vaccine. The interval between vaccinations is 1 month. Therefore, when planning a trip to an area with an increased risk of infection, it is necessary to think about vaccination no later than 1.5 months before the trip. The third revaccination is carried out a year after the second, it gives persistent immunity against two-wave viral meningoencephalitis, which persists for 3 years.