What is encephalitis?

Encephalitis is an inflammation of the brain, usually caused by a viral infection. Although rare, it is potentially life-threatening, and may lead to permanent brain damage or death.

Many different viruses can cause encephalitis, including the herpes simplex virus (HSV – which also causes cold sores) and enteroviruses. In some cases infections are caused by mosquito bites (e.g. Murray Valley encephalitis, also known as Australian encephalitis; equine encephalitis). A milder form of encephalitis can also accompany some of the common childhood diseases such as chicken pox, measles, mumps, and rubella (German measles).

Symptoms of encephalitis

Infectious encephalitis usually begins with a ‘flu-like illness’ or headache followed by more serious symptoms hours to days, or sometimes weeks later. The most serious finding is an alteration in the level of consciousness. This can range from mild confusion or drowsiness, to loss of consciousness and coma. Other symptoms include a high temperature, seizures (fits), aversion to bright lights, inability to speak or control movement, sensory changes, neck stiffness or uncharacteristic behaviour. Autoimmune encephalitis often has a longer onset. Symptoms will vary depending on the type of encephalitis related antibody but may include: confusion, altered personality or behaviour, psychosis, movement disorders, seizures, hallucinations, memory loss, or sleep disturbances.

The after-effects of encephalitis
Nerve cells (neurons) may be damaged or destroyed and this damage is termed acquired brain injury (ABI). No two people affected will have the same outcome. Effects of encephalitis can be long-term. In children, injury to the parts of the brain that are not developed at the time of the illness can manifest later in life, well after the illness with encephalitis. Tiredness, recurring headaches, difficulties with memory, concentration, balance, mood swings, aggression, clumsiness, epilepsy, physical problems (weakness down one side of the body, loss of sensations and of control of bodily functions and movement), speech and language problems, reduced speed of thought and reaction, changes in personality and in the ability to function day-to-day, problems with senses and hormones are reported. The potential impact on social and family relationships should not be underestimated. Returning to work and school can be difficult.