What is Tick-Borne Encephalitis (TBE)?

From the Guidelines

Tick-borne encephalitis (TBE) vaccination should be recommended for travellers exposed outdoors in rural endemic areas to a risk of TBE during the period of transmission, as advised by the World Health Organization (WHO) 1. When considering TBE, it is essential to understand that the risk of infection is present in endemic areas, primarily parts of Europe and Asia. The epidemiology of TBE in international travellers to Western/Central Europe has been studied, and the results suggest that the attack rate for an undefined period of time could be roughly extrapolated to be 0.5–1.3 per 100 000 (1 per 77 000–200 000) overall in Western/Central Europe endemic areas for the exposed at-risk population 1. Some key points to consider in the management and prevention of TBE include:

• Vaccination as the most effective prevention method for those living in or traveling to endemic areas
• The standard vaccination schedule and booster doses for continued protection
• Prevention measures such as wearing protective clothing, using tick repellents, checking for ticks, and removing attached ticks promptly
• The potential for serious neurological complications, including meningitis and encephalitis, if infected The study published in the Journal of Travel Medicine in 2016 1 provides valuable insights into the epidemiology of TBE in international travellers and supports the recommendation for vaccination in at-risk individuals. In terms of prevention and management, it is crucial to prioritize measures that minimize the risk of tick bites, such as:
• Wearing long sleeves and pants
• Using tick repellents containing DEET
• Checking for ticks after outdoor activities
• Removing attached ticks promptly with fine-tipped tweezers By taking these precautions and considering vaccination for those at risk, the likelihood of TBE infection can be significantly reduced, thereby minimizing the risk of morbidity, mortality, and impact on quality of life.

From the Research

Definition and Transmission

• Tick-borne encephalitis (TBE) is an infection of the central nervous system (CNS) caused by tick-borne encephalitis virus (TBEV) and transmitted by ticks 2.
• The virus can also be transmitted through the consumption of raw milk 3, 4.

Epidemiology

• The incidence of TBE in Europe is increasing due to an extended season of the infection and the enlargement of endemic areas 2.
• TBE is found in all age groups, including infants, and the severity of the infection and risk of complications increase with age 3.
• Most cases of TBE occur in spring and autumn, which correlates with increased tick activity 3.

Clinical Manifestations

• The clinical spectrum of TBE ranges from mild meningitis to severe meningoencephalitis with or without paralysis 5.
• Rare clinical manifestations include an abortive form of the disease and a chronic progressive form 5.
• A post-encephalitic syndrome, causing long-lasting morbidity that often affects the quality of life, develops in up to 50% of patients after acute TBE 5, 3.

Diagnosis

• A case of TBE is defined by the presence of clinical signs of meningitis, meningoencephalitis or meningoencephalomyelitis with cerebrospinal fluid (CSF) pleocytosis and the presence of specific TBEV serum immunoglobulin M (IgM) and IgG antibodies, CSF IgM antibodies or TBEV IgG seroconversion 2.
• TBEV-specific polymerase chain reaction in blood is diagnostic in the first viremic phase but it is not sensitive in the second phase of TBE with clinical manifestations of CNS inflammation 2.

Treatment and Prevention

• There is no effective antiviral or immunomodulating therapy available for TBE; therefore, the treatment is symptomatic 2.
• Vaccination against TBE is recommended for all age groups above 1 year in highly endemic areas and for individuals at risk in areas with a lower incidence 2, 6.
• Vaccination can effectively prevent the disease and is indicated for persons living in or visiting TBE endemic areas 5, 6.