Related articles: Tick-borne encephalitis (TBE)
Definition
Tick-borne encephalitis (or TBE, which stands for Tick-Borne Encephalitis) is an acute viral disease that affects the central nervous system. The infection is caused by an arbovirus belonging to the genus Flavivirus (similar to the viral agent that causes yellow fever and dengue).
TBE is mainly transmitted by the tick bite (in particular: Ixodes ricinus and Ixodes persulcatus ), a parasite that acts both as a vector and as a reservoir of the infection. This arthropod is infected by feeding on the blood of animals carrying pathogens (rodents, roe deer, sheep, goats, etc.) and, through subsequent meals, it is able to convey them to new guests, including humans.
The transmission of the infection can also occur through the ingestion of contaminated milk, but this modality is very rare considering that the virus is rapidly inactivated by heat (72 ° C for 10 seconds).
From an epidemiological point of view, TBE is present in endemic outbreaks in many Central-Eastern and Northern European countries; in Italy, it is widespread especially in Trentino Alto Adige, Veneto and Friuli Venezia Giulia. In our territory, the vector Ixodes ricinus prefers damp and shaded wooded areas and attacks mainly in the spring-summer period. Tick-borne encephalitis therefore shows a typical seasonal pattern, which corresponds to periods of maximum activity of ticks.
Most common symptoms and signs *
- Aphasia
- Agnosia
- Apraxia
- Asthenia
- Chills
- cacosmia
- dizziness
- Convulsions
- Difficulty concentrating
- Neck pain
- Articolar pains
- Muscle pains
- Brain edema
- Temperature
- Sore throat
- Headache
- Meningitis
- Nausea
- Paresthesia
- Loss of coordination of movements
- Stiffness in the muscles of the back and neck
- Drowsiness
- Confusional state
- Fainting
Further indications
After an incubation period of 2-28 days after the bite, tick-borne encephalitis occurs in two phases.
At first (viremic phase), the disease can easily be confused with a trivial flu, as it causes fever associated with non-specific symptoms, such as headache, sore throat, sense of tiredness, nausea, muscle and joint pains for 2-4 days. A period of 8-20 days follows, in which the hyperpyrexia disappears and, usually, no further consequences occur.
The second phase is observed only in about 30% of cases: the fever is considerably higher than that of TBE in its classical form and symptoms similar to those of meningitis occur. Furthermore, the involvement of the central nervous system (encephalitis and flaccid paralysis), sometimes with a lethal outcome, is characteristic. Often, tick-borne encephalitis requires hospitalization.
The manifestations of the advanced phase of the disease tend to regress within 2-3 weeks and are followed by a prolonged period of convalescence.
The diagnosis is obtained through serological tests and amplification tests of the viral genetic material (PCR and RT-PCR). Currently, there is no cure for tick-borne encephalitis, so therapeutic measures are supportive. In risk areas, a vaccine is available; furthermore, it is of the utmost importance to adopt protection measures against tick bites.
