Tick-borne Encephalitis (TBE)

Tick-borne encephalitis (TBE) is a viral infectious disease caused by the tick-borne encephalitis virus (TBEV), which is transmitted to humans through the bite of an infected tick. The disease is also known as Central European encephalitis, Russian spring-summer encephalitis, or Frühsommer-Meningo-Enzephalitis (FSME) in German-speaking countries.

Causes and Transmission

TBEV is primarily transmitted to humans through the bite of an infected tick, typically the Ixodes ricinus (wood tick) or Ixodes persulcatus (taiga tick). The virus can also be transmitted through unpasteurized milk and dairy products from infected animals, such as goats, sheep, and cows. In rare cases, TBEV can be transmitted through blood transfusions or organ transplants from an infected donor.

Symptoms

The symptoms of TBE typically occur within 7-14 days after the tick bite and can range from mild to severe. The disease often progresses through three stages:

• Initial stage: Flu-like symptoms, such as fever, headache, fatigue, and muscle pain.
• Asymptomatic period: A brief period of improvement, which can last from a few days to several weeks.
• Neurological stage: Severe symptoms, including meningitis (inflammation of the membranes surrounding the brain and spinal cord), encephalitis (inflammation of the brain), and meningoencephalitis (inflammation of both the brain and its surrounding membranes). Symptoms can include high fever, stiff neck, confusion, seizures, and paralysis.

Diagnosis

TBE is typically diagnosed through a combination of clinical evaluation, laboratory tests, and imaging studies. Diagnostic methods may include:

• Serological tests to detect the presence of TBEV antibodies in the blood or cerebrospinal fluid.
• Polymerase chain reaction (PCR) to detect the viral genome in the blood or cerebrospinal fluid.
• Imaging studies, such as computed tomography (CT) or magnetic resonance imaging (MRI), to evaluate brain inflammation and damage.

Treatment and Prevention

There is no specific antiviral treatment for TBE. Treatment typically focuses on relieving symptoms and supporting the patient's recovery. This may include:

• Antipyretics to reduce fever.
• Pain management medications to alleviate headache and muscle pain.
• Supportive care, such as hydration and rest, to help manage symptoms.

Prevention measures include:

• Avoiding tick-infested areas, especially during peak tick season (spring and summer).
• Wearing protective clothing, such as long-sleeved shirts and pants, when outdoors in tick-prone areas.
• Using insect repellents containing DEET or picaridin to deter ticks.
• Conducting regular tick checks on the body after spending time outdoors.
• Vaccination against TBEV, which is available in some countries and recommended for individuals at high risk of exposure.

Epidemiology

TBE is endemic in many parts of Europe and Asia, with the majority of cases reported in Russia, Eastern Europe, and Scandinavia. The disease typically occurs in areas with temperate climates, where ticks are most active during the spring and summer months.

Complications and Prognosis

TBE can lead to severe complications, including:

• Residual neurological damage, such as cognitive impairment, memory loss, or personality changes.
• Seizures and epilepsy.
• Paralysis or weakness of the limbs.

The prognosis for TBE varies depending on the severity of the disease. In general, patients who receive prompt medical attention and supportive care tend to have a better outcome than those who do not seek medical help promptly.