During February 2018–January 2019, we conducted large-scale surveillance for the presence and prevalence of tick-borne encephalitis virus (TBEV) and louping ill virus (LIV) in sentinel animals and ticks in the United Kingdom. Serum was collected from 1,309 deer culled across England and Scotland. Overall, 4% of samples were ELISA-positive for the TBEV serocomplex. A focus in the Thetford Forest area had the highest proportion (47.7%) of seropositive samples. Ticks collected from culled deer within seropositive regions were tested for viral RNA; 5 of 2,041 ticks tested positive by LIV/TBEV real-time reverse transcription PCR, all from within the Thetford Forest area. From 1 tick, we identified a full-length genomic sequence of TBEV. Thus, using deer as sentinels revealed a potential TBEV focus in the United Kingdom. This detection of TBEV genomic sequence in UK ticks has important public health implications, especially for undiagnosed encephalitis.

The presence of tick-borne encephalitis virus (TBEV) was detected in a questing tick pool in southern England in September 2019. Hitherto, TBEV had only been detected in a limited area in eastern England. This southern English viral genome sequence is distinct from TBEV-UK, being most similar to TBEV-NL. The new location of TBEV presence highlights that the diagnosis of tick-borne encephalitis should be considered in encephalitic patients in areas of the United Kingdom outside eastern England.

Following findings in Northern America of SARS‐CoV‐2 infections in white‐tailed deer, there is concern of similar infections in European deer and their potential as reservoirs of SARS‐CoV‐2 including opportunities for the emergence of new variants. UK deer sera were collected in 2020–2021 from 6 species and a hybrid with 1748 tested using anti‐spike and anti‐nucleocapsid serology assays. No samples were positive on both assays nor by surrogate neutralization testing. There is no evidence that spill‐over infections of SARS‐CoV‐2 occurred from the human population to UK deer or that SARS‐CoV‐2 has been circulating in UK deer (over the study period). Although it cannot be ruled out, study results indicate that spill‐over infections followed by circulation of SARS‐CoV‐2 to the most common European deer species is small.