First Case of Tick-Borne Encephalitis Diagnosed in United Kingdom

The first confirmed domestically-acquired case of tick-borne encephalitis virus (TBEV) was reported in the UK. TBEV was identified in a man who had been bitten by ticks in Yorkshire, and another probable case was detected in the Loch Earn area of Scotland in 2022. The investigators noted that it was not possible to determine conclusively if this second case was TBEV or Louping III virus infection, which are very closely related conditions but with different patterns of infection.

“This study confirms the tick-borne encephalitis virus is present in parts of the UK where there are relevant tick and wildlife populations and may occasionally cause disease in humans,” explains study author Dr Helen Callaby. “Physicians should consider the possibility of tick-borne encephalitis virus when patients present with unexplained encephalitis and a history of tick exposure, even if they have not travelled outside the UK, as the clinicians did in these cases.”

The cases are being presented at next week’s European Congress of Clinical Microbiology & Infectious Diseases conference.

“Although the risk to the general public is very low, it is important for people to take precautions to protect themselves from tick bites, such as covering their ankles and legs, applying insect repellent and checking clothes and your body for ticks, particularly when visiting areas with long grass such as woods, moorlands and parks,” Callaby said.

Before 2019, human TBEV had not been domestically acquired in the UK. In 2019 and 2020, two probable cases were reported, with compatible clinical syndromes, positive serology and lack of exposure abroad. However, for these cases there was no molecular isolation of the virus so they could not be officially confirmed.

In Europe and the United States, more reports are appearing about vector-borne disease and infections.

TBEV cases are on the rise in Europe with some 3,800 reported in 2020, according to the European Centre for Disease Prevention and Control.