The incubation period of the disease starts the moment the virus enters the body, and it can last anywhere from 7-14 days but can last as long as a month. In the first stages of tick-borne encephalitis patients usually present flu-like symptoms (fever, headache, etc.). The second phase, however, starts to involve the central nervous system, and manifests itself as meningitis, in more serious cases encephalitis, in the most severe cases as encephalomyelitis, and rarely as radiculitis (i.e. the inflammation of the spinal nerve roots).