Signs & Symptoms
The period of incubation of TBE is usually 6-14 days and is asymptomatic. Shorter incubation periods have been reported after milk-borne exposure. Initial symptoms lasting for 2-4 days are of fever, headache, nausea and/or vomiting and common-cold-like cough and sniffles.
After about 8 days of remission, the second phase of the disease occurs when the virus enters the central nervous system. The disease manifests as meningitis (inflammation of the membrane surrounding the brain and spinal cord), encephalitis (inflammation of the brain), or meningoencephalitis (inflammation of both the brain and meninges). Symptoms include a stiff neck, severe headache with photophobia (intolerance to light), hyperacusis (intolerance to noise) delirium, paralysis and coma.
Although TBE is most commonly recognised as a neurological disease, long-lasting or permanent neuropsychiatric sequelae are observed in 10-20% of infected patients.