About Tick-Borne Encephalitis
Tick-borne encephalitis virus is a flavivirus, a close relative of the Powassan virus found in North America. It was first described in the Soviet Union in 1937 and has 3 subtypes. The European subtype kills about 1% to 2% of people with symptomatic illness, the Siberian subtype about 6% to 8%, and the Far Eastern subtype about 20%. It is carried by hard ticks of the Ixodes family and, less often, passed through raw dairy products. The virus is not found in US ticks, so every American case comes from travel or residence abroad; most military cases have been in families stationed in Germany.
Many infections are silent. When illness occurs it often comes in 2 phases: a flu-like week, a short recovery, and then encephalitis or meningitis with confusion, poor coordination, speech difficulty, limb weakness or seizures. Between 10% and 50% of people with severe disease have lasting neurological problems. Diagnosis in the United States is done at the CDC, using antibody tests on blood or spinal fluid; because TBE antibodies cross-react with Powassan virus, a specific neutralizing antibody test confirms it. There is no antiviral treatment, and care is supportive.
The vaccine is the main defense. Ticovac, made by Pfizer, was approved by the FDA in August 2021 for people 1 year and older after more than 20 years of use in Europe. It is a 3-dose series: adults 16 and older get the first 2 doses 14 days to 3 months apart and the third 5 to 12 months after the second, with a booster after 3 years if exposure continues. The CDC's advisory committee recommends it for people moving or traveling to an affected area who will have extensive tick exposure from their planned outdoor activities, says it may be considered for others who will be outdoors in tick habitat there, and recommends it for lab workers who handle the virus. The series should be finished at least a week before travel, and it is ordered through a doctor or travel clinic, not bought directly.
Common Symptoms of Tick-Borne Encephalitis
Recognizing the signs of Tick-Borne Encephalitis early can lead to faster diagnosis and better outcomes. Symptoms may vary in severity from person to person. If you or a loved one are experiencing any of the following, consider speaking with a specialist.
- No symptoms at all in many infected people
- Fever, headache, vomiting and weakness about 7 to 14 days after a bite
- A few days of feeling better, then a second phase as the virus reaches the brain
- Confusion, loss of coordination and trouble speaking
- Weakness of the arms or legs and seizures
- Lasting problems with memory, balance or movement in 10% to 50% of severe cases
Who Tick-Borne Encephalitis Affects
People who spend time outdoors in forests and fields in affected parts of Europe and Asia from April through November, including hikers, campers, forestry workers, farmers, field researchers and military families. The highest-risk areas include the Baltic states, Czechia, Slovenia, Austria, southern Germany, Switzerland, Sweden, Russia and northeastern China. Older adults have the most severe disease. The virus can also spread through unpasteurized milk or cheese from infected goats, sheep or cows.
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FDA-Approved Treatments for Tick-Borne Encephalitis
There is currently 1 FDA-approved medication for Tick-Borne Encephalitis. These therapies represent the current standard of care and may be used alongside or compared against investigational treatments in active clinical trials.
Source: openFDA drug labeling data. This list may not include all treatments. Always consult your doctor.
Side Effect Explorer
Real-world side effect reports from the FDA Adverse Event Reporting System (FAERS). Includes both FDA-approved drugs and investigational therapies from active clinical trials. Click any drug to see what patients reported.
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Diagnosis and Testing
Tick-borne viral infection acquired abroad, diagnosed by antibody tests at the CDC; not genetic.
Trusted Tick-Borne Encephalitis Resources
Reputable organizations and medical references for learning more about Tick-Borne Encephalitis, including disease registries, foundation resources, and clinical guidelines.