When viewing this topic in a different language, you may notice some differences in the way the content is structured, but it still reflects the latest evidence-based guidance.

Last reviewed: 19 Sep 2025
Last updated: 29 Apr 2025

Summary

Definition

History and exam

Key diagnostic factors

  • presence of risk factors
  • fever
  • fatigue
  • general malaise
  • headache
  • body pains
  • nausea
  • mild meningitis
  • severe encephalitis
  • altered mental state

Other diagnostic factors

  • cranial and spinal nerve palsies
  • vestibular/hearing defects
  • seizures
  • paresis
  • arms, shoulders, and head muscles paralysis

Risk factors

  • history of recent tick bite
  • summer months
  • occupational exposure
  • outdoors activities
  • recent consumption of raw (unpasteurised) milk or dairy products
  • age ≥45 years
  • bioterrorism

Diagnostic investigations

1st investigations to order

  • FBC
  • erythrocyte sedimentation rate
  • CRP
  • LFTs
  • CT brain
  • cerebrospinal fluid analysis
  • cerebrospinal fluid/serum serology

Investigations to consider

  • cerebrospinal fluid/serum reverse-transcription polymerase chain reaction
  • MRI head
  • EEG

Treatment algorithm

Contributors

Authors

Ashley M. Croft, MA, MBBS, MSc, DTM&H, FFPHM
Ashley M. Croft

School of Pharmacy and Biomedical Science

University of Portsmouth

Portsmouth

UK

Disclosures

AMC declares that he has no competing interests.

Peer reviewers

John Williams, MRCP, DTM&H, DipHIVMed

Consultant Infectious Diseases Physician

The James Cook University Hospital

Middlesbrough

UK

Disclosures

JW declares that he has no competing interests.

Charlie Easmon, MBBS, MRCP, MSc Public Health, DTM&H, DOccMed

Medical Director

Your Excellent Health Service

Honorary Lecturer

UCL

London

UK

Disclosures

CE runs a private travel clinic.

Peer reviewer acknowledgements

BMJ Best Practice topics are updated on a rolling basis in line with developments in evidence and guidance. The peer reviewers listed here have reviewed the content at least once during the history of the topic.

Disclosures

Peer reviewer affiliations and disclosures pertain to the time of the review.

References

Our in-house evidence and editorial teams collaborate with international expert contributors and peer reviewers to ensure that we provide access to the most clinically relevant information possible.

Key articles

Taba P, Schmutzhard E, Forsberg P, et al. EAN consensus review on prevention, diagnosis and management of tick-borne encephalitis. Eur J Neurol. 2017 Oct;24(10):1214-e61. Abstract

UK Health Security Agency. Tick-borne encephalitis: epidemiology, diagnosis and prevention. Apr 2023 [internet publication].Full text

World Health Organization. Tick-borne encephalitis. 2025 [internet publication].Full text

Centers for Disease Control and Prevention. Tickborne diseases of the United States. May 2024 [internet publication].Full text

Reference articles

A full list of sources referenced in this topic is available here.

Use of this content is subject to our disclaimer