Microbe of the Week is written by undergraduate researcher Maria Bergquist

 

Microbe of the Week: Tick-Borne Encephalitis

Welcome to microbe of the week, where we break down the different disease-causing microbes that lurk inside our tick vectors!  This week’s microbe is 

Tick-Borne Encephalitis virus, which causes Tick-Borne Encephalitis (TBE).

What is the TBE virus?

Tick-borne encephalitis is a viral infection that specifically targets the central nervous system. TBE virus is from the genus flavivirus, the same genus that houses diseases like West Nile virus and Zika virus. This virus is primarily found along the southern border of Russia into eastern Europe but has also been found throughout other parts of Europe and Asia. A similar virus under the same genus, Powassan virus, has been reported in the United States.

The current known reservoir host for TBE virus is primarily small rodents like voles and mice. TBE virus is transmitted to humans and other animals by Ixodes ricinus in Europe and Ixodes persulcatus in Russia. TBE virus may also be contracted by consuming unpasteurized dairy products from infected animals.

Symptoms

The CDC reports symptoms of TBE as fever, achiness, loss of appetite, headache, nausea, and vomiting. They note that swelling of the brain and/or spinal cord, confusion, and sensory disturbances occur in 20-30% of cases. Symptoms occur on average after seven days but have been reported taking up to 28 days post tick bite.

Treatment

There is no known cure for TBE or Powassan Virus Disease. Medical intervention primarily involves symptom management, which is required in cases of encephalitis. Vaccines for TBE are available in some endemic areas.

A Condensed History

• 1936 — TBE described as epidemic encephalitis along the border of Russia and Japan. 
• 1937 — First isolation of TBE virus lead by Russian Virologist Lev Zilber. 
• 1941 — First vaccine for TBE developed. 
• 1970 — First case of Powassan virus discovered in the US. 
• 2019 — Reported cases of TBE range from 5,000 to 13,000 per year.