Prevention of tick-borne encephalitis
Specific protection against the tick-borne encephalitis virus is based on two main approaches:
- Routine prophylaxis: a tissue-inactivated vaccine is used to induce durable immunity before the start of the epidemic season.
- Emergency prophylaxis: in the event of a tick bite in an unvaccinated individual, anti-tick gamma globulin is administered. The product is derived from the plasma of immunized donors and contains preformed antibodies against the virus.
Lyme disease (tick-borne borreliosis)
This is another vector-borne disease transmitted by the bite of ixodid ticks. The causative agent is a spirochete (Borrelia). The disease is endemic to Europe and North America.
Clinical presentation develops in stages:
- Skin manifestations: chronic migrating (annular) erythema forms at the site of the bite. The lesion gradually enlarges, and additional spots may occasionally appear. This may be the sole symptom of the disease.
- Systemic complications: weeks or months later, approximately 66% of patients develop arthritis. Cardiac involvement is less common.
- Neurological manifestations: occur in 10–15% of cases. They include meningoencephalitis (headache, nausea, nuchal rigidity), cranial nerve involvement (most commonly facial nerve neuritis), and peripheral nervous system involvement (radiculoneuritis).
Poliomyelitis (infantile paralysis)
An acute viral disease characterized by damage to the anterior horn motor neurons of the spinal cord and motor nuclei of the brainstem. Children aged 6 months to 10 years are at the highest risk.
Etiology and transmission The primary pathogen is poliovirus. The infection is transmitted mainly via the alimentary route, and less frequently via airborne droplets.
Stages of the disease (incubation period 3–35 days, averaging 17):
- Preparalytic stage: malaise, fever, gastrointestinal disturbances. Aseptic meningitis (headache, meningeal signs) develops later. In the majority of patients, the disease ends here.
- Paralytic stage: develops in only 1–2% of patients after 2–5 days. Peripheral paresis occurs (ranging up to tetraplegia), with the lower extremities most commonly affected. Muscle hypotonia and areflexia are observed.
- Recovery: begins by the end of the first week. Many patients retain persistent paresis, muscle atrophy, and stunted bone growth in the affected limbs.
Prevention and treatment Treatment in the acute phase is symptomatic. Orthopedic surgical correction may be performed 2 years after rehabilitation is complete. The mainstay of combating poliomyelitis is vaccination with attenuated live viruses (two doses in newborns, revaccination at 1 and 4 years of age). The risk of vaccine-associated paralytic poliomyelitis is negligibly small (0.02–0.04 per 1 million cases).
Transverse myelitis
Focal viral inflammation of the spinal cord developing a few days or weeks after an infection.
Symptomatology:
- Neck or back pain.
- Lower central paraparesis (rarely tetraparesis), weakness, and numbness in the legs.
- Tract-type sensory disturbance on the trunk.
- Bladder and bowel dysfunction.
Diagnostics:
- Cerebrospinal fluid: lymphocytic pleocytosis (10–100 cells/mm³), mild protein elevation, normal glucose.
- MRI: signal change (T2-weighted) spanning 2–3 segments, faint contrast enhancement (gadolinium) on T1-weighted imaging.
Treatment: First-line agents are corticosteroid pulse therapy (methylprednisolone 500–1000 mg/day IV for 3–5 days). Plasmapheresis or intravenous human immunoglobulin G is used as an alternative.
Briefly: answers to topical questions
What are the clinical forms of tick-borne encephalitis classified by symptomatology?
Depending on the clinical symptoms, sources identify the following forms of tick-borne encephalitis:
- Febrile form.
- Meningeal form — the most frequent, accounting for 50–60% of TBE cases; leading syndromes: intoxication, meningeal, hypertension, inflammatory CSF changes.
- Meningoencephalitic form.
- Poliomyelitic form — described in diagnosis examples with flaccid paresis, such as upper monoparesis and neck muscle paresis.
- Polioencephalomyelitic form — very severe course, high mortality; leading syndrome: cranial nerve involvement.
- Meningoencephalopoliomyelitic form — described in diagnosis examples with bulbar syndrome, extraocular nerve palsy, neck muscle paralysis, tetraplegia.
- Progressive form — listed as a form of tick-borne encephalitis classified as a slow virus infection.
Which cranial nerves may be affected during the neurological stage of Lyme disease?
During the neurological stage of Lyme disease (neuroborreliosis), monoparesis of various cranial nerves may develop.
- Facial nerve — most frequently affected; its neuritis is part of the pathognomonic Bannwarth syndrome (along with lymphocytic meningitis and radiculoneuritis).
- Abducens nerve (n. abducens) — also among the cranial nerves most frequently involved in the pathological process.
Involvement of these nerves is identified during a neurological examination to determine the extent of central and peripheral nervous system involvement.
Which antibacterial drugs are used for the etiotropic treatment of Lyme disease?
For the etiotropic treatment of Lyme disease, sources list the following antibacterial agents:
- Penicillin — for tick bites with erythema migrans; for neurological disorders — intravenously at a high dose of 20 million IU/day.
- Ceftriaxone — for neurological disorders: 2 g/day IV for 2 weeks; also specified in the infectious diseases clinical case as ceftriaxone 2 g once daily intramuscularly for a 14–28 day course.
- Tetracycline — for tick bites and the development of erythema migrans to prevent cardiac, articular, and neurological complications.
- Erythromycin — for tick bites and the development of erythema migrans to prevent cardiac, articular, and neurological complications.
To remember the pathogens causing a poliomyelitis-like syndrome, use the acronym "PEM": Parotitis, ECHO, Coxsackie.
Class and exam questions
What is the difference between routine and emergency prophylaxis for tick-borne encephalitis?
Routine prophylaxis is carried out in advance using a tissue-inactivated vaccine. Emergency prophylaxis is used after a tick bite and consists of administering preformed antibodies — tick-borne immunoglobulin.
What neurological complications are typical for Lyme disease?
In 10–15% of cases, meningoencephalitis, peripheral neuritis, radiculoneuritis, and cranial nerve involvement (especially the facial nerve) develop.
How to differentiate transverse myelitis based on lumbar puncture results?
Cerebrospinal fluid reveals lymphocytic pleocytosis (10–100 cells/mm³), a slight increase in protein level with normal glucose concentration.
What else to study on this topic
- Pathogenesis of tick-borne encephalitis virus crossing the blood-brain barrier.
- Differential diagnosis of peripheral and central paresis in poliomyelitis and myelitis.
- Orthopedic surgical correction of poliomyelitis sequelae.
- Antibiotic treatment regimens for Lyme disease (borreliosis).
Master the entire topic in the "Neurology" course
This is a summary. The course covers everything tested in classes and exams.
- Complete study guide on "Tick-borne encephalitis" and 907 more pages on the subject
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 32 video lessons for the subject
Other topics in "Chapter 23. Infectious Diseases of the Nervous System"
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.