Last reviewed: 24 Jan 2021
Last updated: 29 Sep 2020
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 ≥50 years
- bioterrorism
Diagnostic investigations
1st investigations to order
- FBC
- ESR
- 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

School of Pharmacy and Biomedical Science
University of Portsmouth
Portsmouth
UK
Disclosures
AMC declares that he has no competing interests.
Peer reviewers
Consultant Infectious Diseases Physician
The James Cook University Hospital
Middlesbrough
UK
Disclosures
JW declares that he has no competing interests.
Medical Director
Your Excellent Health Service
Honorary Lecturer
UCL
London
UK
Disclosures
CE runs a private travel clinic.
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