Encephalitis

Encephalitis is an inflammation of the brain. It is usually caused by a virus. It is rare, but can be life-threatening. Encephalitis can lead to permanent brain damage or death.

Encephalitis can start with flu-like symptoms and progress to severe neurological problems.

Flu-like symptoms may include:

• high fever and weakness
• headaches
• nausea and vomiting

Neurological symptoms can appear suddenly, and may include:

• confusion
• sensitivity to light or vision changes
• seizures
• difficulty moving or controlling your body
• neck stiffness
• drowsiness or decreased consciousness

Babies and children with encephalitis may have similar symptoms. Babies may also have a bulging fontanelle (Opens in new tab) (the 'soft spot' of the head starts to swell).

Many of these symptoms can be caused by other conditions. If you experience any of these symptoms, see your doctor so they can diagnose and treat you appropriately.

Encephalitis can be caused by an infection or by your immune system.

Herpes simplex virus (HSV) is the most common infection that causes encephalitis.

Other infections that can cause encephalitis include but is not limited to:

• enteroviruses (Opens in new tab)
• toxoplasmosis
• viruses transmitted by mosquito bites, such as Murray Valley encephalitis and Japanese encephalitis
• chicken pox
• measles
• mumps
• rubella (German measles)

Autoimmune encephalitis happens when your immune system attacks your brain by mistake.

In some cases, the cause of encephalitis cannot be found.

Encephalitis is diagnosed with tests to look for the cause and severity, which may include:

• MRI or CT scan of your brain
• lumbar puncture (LP)
• blood tests
• a swab taken from your nose or throat
• urine tests or stool tests
• an EEG (electroencephalogram)

Rarely, a brain biopsy may be needed, if you are not getting better and no cause has been found.

Encephalitis treatment depends on the cause and severity.

Treatment with medicines may include:

• antiviral or antibiotic medicines
• pain relief medicines
• medicines to prevent seizures
• steroid medicines to reduce inflammation
• medicines to lower your immune system's response

You may also be treated with:

• intravenous fluids — fluids given directly into a vein
• respiratory support — if you have a severe infection, you may need help breathing

While you recover, you may benefit from therapies:

• speech therapy
• occupational therapy
• physiotherapy

These therapies can help you manage any long-lasting symptoms.

Encephalitis can lead to serious problems for both adults and children. Your risk of having complications depends on your age and the severity of your condition. Very young children and older adults are at a higher risk of complications. Encephalitis in some cases can cause death.

Complications in adults may include:

• epilepsy
• difficulty with your memory and concentration
• difficulty with balance and control of your bodily functions
• headaches and fatigue
• changes to your mood and behaviour
• difficulty speaking

Complications in babies and children may include:

• infections
• hearing loss (Opens in new tab)
• epilepsy (Opens in new tab)
• hydrocephalus (fluid build-up in or around the brain)
• developmental delays

Babies may need regular follow-up to check their hearing and development (Opens in new tab).

Some infections that cause encephalitis can be prevented through vaccination. For example, the measles, mumps, rubella and varicella vaccines are all part of the routine childhood vaccines recommended in Australia.

Sometimes viruses that cause encephalitis are transmitted via mosquito bites. Mosquito bite prevention (for example, using mosquito repellent, mosquito nets and wearing long sleeves) can help reduce spread of these viruses.

• Visit the Brain Foundation (Opens in new tab) for information on encephalitis.
• Fight The Bite (Opens in new tab) provides information on how to protect yourself and your family from mosquito bites.
• You can also call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available 24 hours a day, 7 days a week.

Do you prefer to read in languages other than English?

The Royal Children's Hospital provides translated information on fevers in babies (Opens in new tab) in several community languages.

Looking for information for Aboriginal and/or Torres Strait Islander people?

The Australian Government Department of Health, Disability and Ageing has resources about Japanese encephalitis (JEV) (Opens in new tab).