Stage 1: Epidemiological and clinical history
The first step in the diagnostic search is a thorough collection of information. Special attention is paid to the epidemiological history. The physician must find out whether the patient visited endemic foci during the spring-autumn period and whether a tick attachment occurred. The incubation period ranges from 1 to 30 days.
It is important to assess the patient's premorbid background:
- Status of routine vaccination and emergency passive immunization;
- Past acute and chronic diseases, including tick-borne encephalitis itself;
- Presence of factors predisposing to a severe course (traumatic brain injuries, neurosurgical interventions, immunodeficiency states);
- Long-term use of immunosuppressive therapy (cytostatics, hormonal drugs, chemotherapy).
The onset of the disease is always acute. Patients complain of fever, severe chills, headache, dizziness, nausea, vomiting, and general weakness. Severe myalgia with an emphasis on pain in the muscles of the upper extremities and shoulder girdle is characteristic.
Stage 2: Physical examination and complications
During the physical examination, the physician evaluates the dynamics of symptom development. A key sign is the emergence of neurological symptoms against the background of an already developed intoxication syndrome. There is a progression of meningeal and encephalitic manifestations.
Specific complications develop a few days (usually 3–4 days) after the manifestation of the disease:
- Distal flaccid paralysis of the upper extremities develops;
- In severe cases, the muscles of the face and oropharynx are involved in the pathological process;
- Damage to the respiratory muscles leads to progressive respiratory failure (specific laboratory diagnostics for this specific condition are absent).
Stage 3: Specific laboratory diagnostics
Definitive confirmation of the diagnosis of tick-borne encephalitis is impossible without specific analyses. Two main methods are used:
- Serological studies (ELISA): aimed at detecting antibodies to the virus in blood serum. A 4-fold increase in antibody titer upon dynamic evaluation is considered an absolutely diagnostically significant criterion.
- Molecular genetic studies (PCR): allow obtaining a positive result for the presence of the virus RNA itself (for example, in the cerebrospinal fluid).
Stage 4: Differential diagnosis
The disease must be strictly differentiated from a number of pathologies with a similar clinical course. The differential diagnosis algorithm includes:
- Polyneuropathies of various genesis;
- Congenital hereditary pathologies of the nervous system;
- Primary or secondary encephalitides. These include lesions developing after bites of other insects or acting as complications of other infections: measles, rubella, mumps, varicella, leptospirosis, herpes, West Nile fever, syphilis.
Stage 5: Formulation of a detailed diagnosis
The final clinical diagnosis must be as detailed as possible. It must indicate:
- Clinical form (febrile, meningeal, meningoencephalitic, etc.);
- Severity degree, which is assessed by the severity of intoxication, meningeal and encephalitic syndromes, focal symptoms, respiratory function, and hemodynamic status;
- Results of laboratory tests (serology, PCR) and the presence of complications.
Example of correct formulation: "Tick-borne encephalitis, meningoencephalitic form, severe course. Complication: cerebral edema-swelling (IgM antibody titers 1:200 dated 23.08.2018; increase to 1:2560 dated 05.09.2018)."
Management tactics after diagnosis
After confirming the diagnosis, further tactics are determined. The patient is subject to mandatory hospitalization in an infectious disease or neurological hospital (transportation exclusively on a stretcher). Strict bed rest is prescribed until intoxication disappears — a direct connection has been proven between the patient's activity during the fever and the severity of subsequent focal lesions.
The basis of etiotropic treatment is the intramuscular administration of specific immunoglobulin (0.1–0.15 ml/kg body weight). Discharge of the convalescent is allowed no earlier than 2–3 weeks after temperature normalization and with the complete absence of meningeal signs.
Briefly: answers to topical questions
What clinical forms of tick-borne encephalitis are distinguished in the classification?
The clinical classification distinguishes forms according to the course of the process, severity, and leading syndromes.
According to the form of the infectious process course:
- Acute
- Chronic
- Subclinical (latent form)
Clinical forms of acute TBE according to leading syndromes:
- Febrile
- Meningeal
- Meningoencephalitic
- Poliomyelitic
- Polyradiculoneuritic
According to the number of temperature waves in acute TBE, single-wave and two-wave forms are distinguished. Clinical forms of chronic TBE: primary progressive, secondary progressive, and subacute.
What changes in the cerebrospinal fluid are characteristic of the meningeal form of tick-borne encephalitis?
The meningeal form is characterized by a picture of serous meningitis. The appearance of the cerebrospinal fluid is transparent, slightly opalescent. Pressure is elevated (200-350 mm H2O). Moderate lymphocytic pleocytosis is detected (100-300 cells/µl, rarely more). Neutrophils may predominate in the first days, but they completely disappear by the end of the 1st week. The protein level does not exceed 1-2 g/l. Changes in the cerebrospinal fluid persist for a long time, and its sanitation lags behind clinical improvement.
What classes of antibodies (Ig) and at what timeframes are investigated by ELISA to confirm tick-borne encephalitis?
Antibodies to the tick-borne encephalitis virus of classes IgM and IgG are determined in the blood using serological diagnostics.
- Antibodies of the IgM class are investigated starting from the 3rd–4th day of the disease.
- Antibodies of the IgG class are investigated after the 5th–7th day from the onset of the disease.
If the IgG result is negative, the analysis is recommended to be repeated dynamically 10–14 days after the first study to assess seroconversion.
To assess severity, remember the rule "I-M-E-S" (Intoxication, Meningeal syndrome, Encephalitic syndrome, Focal symptoms).
Class and exam questions
Which laboratory methods confirm tick-borne encephalitis?
The diagnosis is confirmed by ELISA methods (detection of antibodies and their 4-fold dynamic increase) and PCR (detection of virus RNA).
Which neurological complications are most typical?
The development of distal flaccid paralysis of the upper extremities is characteristic. In severe cases, the muscles of the face, oropharynx, and respiratory muscles are affected, leading to respiratory failure.
With which infections should tick-borne encephalitis be differentiated?
With encephalitides against the background of measles, rubella, mumps, varicella, leptospirosis, herpes, West Nile fever, and syphilis.
What else to study on this topic
- Aetiotropic therapy with specific immunoglobulin: dosages and regimens
- Pathogenetic and symptomatic treatment of severe forms
- Specific and non-specific prophylaxis of tick-borne encephalitis
- Rules for emergency prophylaxis after a tick bite
- Rehabilitation, discharge criteria, and follow-up dispensary observation
Master the complete topic in the «Infectious Diseases» course
This is a summary. The course covers everything tested in classes and exams.
- Complete guideline on "Diagnosis of Tick-Borne Encephalitis" and another 3,312 pages of the subject
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Other topics in the "Vector-borne infections" section
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.