UK Health Security Agency. Tick-borne encephalitis: epidemiology, diagnosis and prevention. GOV.UK website. Updated August 20, 2026. Accessed September 22, 2026. Tick-borne encephalitis: epidemiology, diagnosis and prevention
Until 2019, tick-borne encephalitis virus (TBEV) was not considered to occur in the United Kingdom. This changed when TBEV was detected for the first time in ticks collected in the UK. In the same year, the first probable locally acquired human case of tick-borne encephalitis (TBE) was diagnosed following a tick bite in the New Forest, Hampshire.
Since then, TBEV-infected ticks have been detected in several areas of England, including Thetford Forest, the Hampshire–Dorset border and parts of the North Yorkshire Moors.
Human infections have also continued to emerge. As of August 2026, a total of 10 UK-acquired confirmed or probable TBE or TBE-complex cases had been reported.
Diagnosis and surveillance of TBE in the UK are complicated by the circulation of louping ill virus (LIV), a closely related flavivirus belonging to the TBE virus complex. Serological cross-reactivity between TBEV and LIV can make it difficult to distinguish between infections caused by the two viruses. Where a definitive distinction cannot be made, cases may therefore be classified as TBE-complex rather than specifically as TBE.
Notably, the reported human cases have not been confined to a single geographical focus. Instead, confirmed and probable cases have been associated with geographically dispersed locations across Great Britain, extending from southern England to Scotland.
The current UK Health Security Agency (UKHSA) map shows the probable location of the 10 reported cases:
TBE and TBE-complex cases by probable location of acquisition
One confirmed TBE-complex case was acquired in the North Yorkshire Moors.
One confirmed TBE-complex case was acquired around the Loch Earn area in Scotland.
One probable case was acquired in Dartmoor.
One confirmed TBE case and five probable TBE-complex cases were acquired in Hampshire.
One probable TBE-complex case was associated with possible exposure in either the Peak District, South Yorkshire or Na h-Eileanan Siar (Outer Hebrides); the precise location of acquisition could not be determined.
The geographical distribution of these cases demonstrates that locally acquired TBE and TBE-complex infections in the UK are not restricted to a single location. However, the small number of reported human cases and the geographically dispersed pattern should not be interpreted as evidence of widespread or continuous TBEV transmission across Great Britain.
Surveillance of TBEV in the UK is continuing. The Human Animal Infections and Risk Surveillance (HAIRS) Group assesses emerging evidence on TBEV circulation and the associated risk to human health, while UKHSA continues surveillance of ticks, human cases and other relevant epidemiological indicators.