Holding, Maya 
ORCID: 0000-0001-6666-5855
(2021)
Investigating the presence of tick-borne encephalitis virus in the United Kingdom.
PhD thesis, University of Liverpool.
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Abstract
Louping ill virus (LIV), a member of the tick-borne encephalitis virus (TBEV) serocomplex, had been the only known zoonotic tick-borne flavivirus endemic to the UK. LIV is closely related to and serologically reacts with TBEV, which is much more pathogenic to humans; causing around 3,000 cases in the European region annually. TBEV is endemic across much of Europe, where it is increasing in range, but was thought to be absent from the UK. It is important to understand the potential for TBEV to be emerging in the UK undetected. A large-scale sentinel deer serosurveillance study was conducted to identify regions of exposure to TBEV-serocomplex pathogens. Serum samples were tested for specific antibodies to TBEV as a measure to indicate exposure. In addition, submitted tick samples removed from deer, close to an ELISA positive sample, were tested for TBEV and LIV RNA by RT-PCR. Overall, 4% of samples were ELISA-positive for the TBEV serocomplex. The Thetford Forest area in England had both the highest proportion (47.7%) of seropositive samples, and importantly no previous reports of LIV infection in livestock which could cross-react with the TBEV serology assays. Of 2,041 tested ticks from areas near seropositive deer, five were positive by TBEV/LIV RT-PCR, all within the Thetford Forest area. From 1 tick, a full-length genomic sequence of TBEV-Eu was identified. A two-year extensive ecological study collecting questing ticks was conducted in sites associated with high rates of exposure to TBEV-serocomplex virus. A total of 7,085 questing ticks were collected in Thetford Forest, with TBEV being detected in 6 sites out of 24 sites surveyed over 2018 and 2019. In addition, 3,205 questing ticks were collected and tested from 7 sites in the New Forest and bordering areas, resulting in the detection of TBEV in one site on the Hampshire/Dorset border. These results demonstrate that TBEV has been detected in the UK for the first time - in two geographically distinct locations 200 miles apart. High seropositivity and presence in questing ticks suggests it is being maintained in enzootic cycles in these areas. This finding is of public health significance and requires rapid dissemination of findings to health professionals in the UK.
| Item Type: | Thesis (PhD) |
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| Divisions: | Faculty of Health and Life Sciences |
| Depositing User: | Symplectic Admin |
| Date Deposited: | 06 Sep 2022 07:45 |
| Last Modified: | 01 Aug 2023 01:30 |
| DOI: | 10.17638/03149344 |
| Supervisors: |
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| URI: | https://livrepository.liverpool.ac.uk/id/eprint/3149344 |
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