Tick-borne encephalitis (TBE), or spring-summer meningoencephalitis, is an acute viral disease of the central nervous system, caused by an arbovirus belonging to the genusFlavivirus,which is very similar to the viruses responsible for yellow fever anddengue.Tick-borne encephalitis was first identified in Italy in 1994 in the province of Belluno. From an epidemiological perspective, TBE is now present in endemic outbreaks in many countries of Central and Northern Europe, including Italy. In particular, in our country, 35 cases of the disease were identified in the province of Belluno from 1994 to 1999.
Ticks, and in particularIxodes ricinusandIxodes persulcatus, act both as vectors and reservoirs. Ticks of the genusDermacentor(dog tick) andHaemaphysaliscan also transmit the infection.
The virus transmitted by ticks infects various animals, both wild and domestic, including rodents, roe deer, sheep, and goats, which contribute to maintaining the cycle of transmission of the infection. Birds likely contribute to the passive transport of infected ticks over considerable distances during their migrations.
After an infected tick bite in humans, in about 70% of cases, an infection manifests with either no symptoms or mild symptoms, which can go unnoticed. In the remaining 30% of cases, after 3-28 days from the tick bite, there is an initial phase with flu-like symptoms such as high fever, significant headache, sore throat, fatigue, and muscle and joint pain lasting 2-4 days. Then the temperature drops and generally there are no further consequences. In 10-20 percent of these cases, after an interval without symptoms of 8-20 days, a second phase begins characterised by central nervous system disorders (encephalitis, flaccid paralysis with a fatal outcome in 1% of cases).
In children and younger individuals, TBE generally shows a milder course, with a progressive increase in severity as age advances.
Source:Higher Institute of Health