tick-borne encephalitis virus

Classification

• European or Western tick-borne encephalitis virus
• Siberian tick-borne encephalitis virus
• Far eastern Tick-borne encephalitis virus (formerly Russian Spring Summer encephalitis virus)

Epidemiology

• transmitted by Ixodedes ticks
• Europe, former Soviet Union, Asia
• may also bemilk-borne exposure

Clinical manifestations

• incubation period of 7-14 days (asymptomatic)
• initial phase of 2-4 days corresponds to viremic phase
  • fever, malaise, anorexia, myalgia, headache, nausea/vomiting
• followed by 8 days of remission
• second phase of the disease occurs in 20-30% of patients
  • meningitis
  • encephalitis
• symptoms may be limited to mild febrile illness
• disease more severe in adults than in children

Laboratory

• complete blood count
  • leukopenia
  • thrombocytopenia
• liver function tests
  • serum transaminases may be mildly elevated
• CSF analysis
  • lymphocytosis
• virus can be isolated from the blood during the first phase
• European tick borne encephalitis virus serology
  • specific IgM in either blood or CSF, during the second phase of the disease
• - European tick borne encephalitis virus RNA

Complications

• mortality 1-2%m generally 5-7 days after onset of neurological symptoms
• chronic or permanent neuropsychiatric sequelae are observed in 10-20% of infected patients

Management

• treatment is supportive
• endotracheal intubation & mechanical ventilation may be needed
• a vaccine is available in some disease endemic areas
  • not currently available in the United States
  • adverse vaccine-reactions in children limit its use

More general terms

• flaviviridae
• encephalitis virus

Additional terms

• tick borne infection