What are the symptoms?
Symptoms usually appear over hours or a few days, often beginning with:
- Fever
- Headache
- Neck stiffness
- Sometimes a rash that does not fade under pressure
This is followed by:
- Confusion
- Drowsiness
- Changes in behaviour or personality
- Seizures
- Weakness in one side of the body
- Difficulty speaking
How is it diagnosed?
A lumbar puncture (LP) is used to take a sample of cerebrospinal fluid (CSF), which is then examined for inflammatory cells and tested for bacteria using culture and PCR.
Blood tests, brain scans (CT or MRI) and an EEG may also be used.
How is it treated?
- Antibiotics are given intravenously as soon as bacterial encephalitis is suspected, before test results are available.
- Antiviral treatments are often given alongside until a viral cause is excluded.
- Steroids may also be used to reduce inflammation.
- Some people may require intensive care or anti-seizure medications.
- Tuberculosis as a result of bacterial encephalitis requires months of treatment.
What are the outcomes?
If treatment starts early, many people recover well.
Some people are left with lasting difficulties. This includes:
- Fatigue
- Problems with memory and concentration
- Epilepsy
- Hearing loss
- Weakness
Can it be prevented?
Yes. Vaccines protect against several causes including meningococcal and pneumococcal bacteria.
Avoiding tick bites reduces the risk of Lyme disease. If walking in affected wooded or rural areas, it is recommended to wear long trousers/sleeves to cover exposed skin, use an insect repellent that is effective against ticks, and inspect your skin for ticks regularly.
By Prav Prathapan, Encephalitis International (awaiting peer review)
FS089V1 Bacterial encephalitis
Date created: September 2026 / Last updated: September 2026 / Review date: September 2029
Disclaimer: We try to ensure that the information is easy to understand, accurate and up-to-date as possible. If you would like more information on the source material and references the author used to write this document please contact Encephalitis International. None of the authors of the above document has declared any conflict of interest, which may arise from being named as an author of this document.
