TICK-BORNE ENCEPHALITIS

Tick-borne encephalitis (TBE) is the cause of viral infections of the central nervous system in eastern, central, northern, and increasingly western European countries, and in north China, Mongolia, and the Russian Federation. 

 

Approximately 10 000–12 000 clinical cases of tick-borne encephalitis are reported yearly.

Most virus infections result from infected ticks, which often remain firmly attached to the skin for days. The infection can result from consuming unpasteurized milk from infect goats, sheep, or cows on rare occasions. People come in contact with the ticks during outdoor activities in forested areas up to an altitude of about 1.2 miles. There is no direct person-to-person transmission.

Image by Victor Grabarczyk

Most infected people show no symptoms at all. In those that do have symptoms (2-30%), they typically appear about one-two week after the bite. Of those with initial symptoms, one-third will develop neurological symptoms.

 

For those who develop symptoms, fever, headache, fatigue, and malaise tend to occur and last for about five days. Following a short period of symptom-free time, more severe manifestations may develop, including meningitis, encephalitis, myelitis, and cranial neuritis. 

 

There is currently no cure for TBE, so treatment includes helping relieve symptoms and make a person feel as comfortable as possible until the infection has passed.

On August 13, 2021, the Food and Drug Administration approved a tick-borne encephalitis (TBE) vaccine, TICOVAC™, manufactured by Pfizer. The vaccine is an inactivated vaccine licensed and used in Europe for approximately 20 years. The vaccine has both pediatric and adult formulations and is the only one currently licensed in the United States.

 

The vaccine is not part of the routine childhood vaccination schedule.

 

An Advisory Committee on Immunization Practices (ACIP) Work Group was formed in 2020 to discuss the use of the TBE vaccine in children and adults traveling to or residing in areas at risk and laboratory workers. The Work Group is currently reviewing the epidemiology of TBE and data on the safety and effectiveness of the TBE vaccine. The Work Group is developing evidence-based recommendations for consideration by ACIP, which will likely be approved in 2022.