Encephalitis: symptoms, causes, tests, treatment and recovery

The NHS says symptoms may be mild to begin with but can become more serious over hours or days, and occasionally develop gradually over several weeks or even months. The first symptoms can be similar to flu: a high temperature, a headache, feeling and being sick, and aching muscles and joints. Some people also have a spotty or blistery rash. These early symptoms do not always appear, and sometimes the first signs are more serious.

More severe symptoms develop when the brain is affected. The NHS lists:

• Confusion or disorientation, and drowsiness.

• Seizures or fits.

• Changes in personality and behaviour, such as feeling very agitated.

• Difficulty speaking.

• Weakness or loss of movement in some parts of the body, or loss of feeling in certain parts of the body.

• Seeing and hearing things that are not there (hallucinations).

• Uncontrollable eye movements, and eyesight problems.

• Loss of consciousness.

• There may also be symptoms of meningitis, such as a severe headache, sensitivity to bright lights, a stiff neck and a spotty rash that does not fade when a glass is pressed against it.

The NHS says to dial 999 immediately to request an ambulance if you or someone else has serious symptoms of encephalitis. It is a medical emergency that needs to be seen in hospital as soon as possible. The earlier treatment is started, the more successful it is likely to be.

Encephalitis International describes encephalitis as an inflammation of the brain, caused either by an infection invading the brain (infectious encephalitis) or by the immune system attacking the brain in error (post-infectious or autoimmune encephalitis). It says anyone at any age can get it.

The NHS says the very young and very old are most at risk. It is uncommon, and many of the infections associated with it are quite common and usually mild, with encephalitis happening only in rare cases.

No. The NHS says you cannot catch encephalitis from someone else. It says you can catch some of the infections that can cause it, such as rare bacterial, fungal or parasitic infections, from someone else, but encephalitis itself is not spread from person to person.

Some types are spread by animals: the NHS lists mosquitoes (Japanese encephalitis), ticks (tick-borne encephalitis) and mammals (rabies).

The NHS says it is not always clear what causes encephalitis, and when a cause is found it is usually an infection or a problem with the immune system.

The NHS says the symptoms of encephalitis can have a number of possible causes, so several tests may be needed.

• Brain scans: a CT scan or MRI scan can show whether you have encephalitis or another problem such as a stroke, brain tumour or brain aneurysm.

• Lumbar puncture: a needle is inserted into the lower spine under local anaesthetic to remove fluid from around the spinal cord, which is checked for signs of infection or an immune system problem.

• Electroencephalogram (EEG): electrodes on the scalp pick up electrical signals from the brain and show abnormal activity.

• Tests of blood, urine or other bodily fluids to check for infection.

The NHS says encephalitis needs to be treated urgently, in hospital, usually in an intensive care unit. Treatment involves tackling the underlying cause, relieving symptoms and supporting bodily functions. How long someone needs to stay in hospital can range from a few days to several weeks or even months.

The NHS says encephalitis is serious: although some people will make a good recovery, it can cause persistent problems and can be fatal. For example, encephalitis due to the herpes simplex virus (the most common type) is fatal in 1 in 5 cases even if treated, and causes persistent problems in around half the people who have it. The chances of successful treatment are much better if it is diagnosed and treated quickly.

Common complications are memory loss, personality and behavioural changes, speech and language problems, swallowing problems, repeated seizures (epilepsy), anxiety, depression and mood swings, problems with attention, concentration, planning and problem solving, problems with balance, co-ordination and movement, and persistent tiredness.

The NHS says recovery can be a long, slow and difficult process, and many people never make a full recovery. Rehabilitation may involve a neuropsychologist, occupational therapist, physiotherapist and speech and language therapist, and an individual care plan is drawn up before leaving hospital.

The NHS says it is not always possible to prevent encephalitis, but some of the infections that cause it can be prevented by vaccination. These include the MMR vaccine, routinely offered to all children in England, and vaccines recommended for travellers to at-risk areas: Japanese encephalitis, tick-borne encephalitis (for certain parts of Europe and Asia, but not the UK) and rabies. Speak to a GP surgery if you are not sure whether your vaccinations are up to date or you are planning to travel abroad.

The NHS says the very young and very old are most at risk. The NHS says serious symptoms need a 999 call. The MMR vaccine, a routine childhood vaccination, helps prevent measles, mumps and rubella, which are among the viral causes.

Suspected encephalitis is assessed through 999 and hospital emergency departments, with treatment in hospital often in intensive care. There is no role for a routine or private appointment in the acute phase.

After hospital, rehabilitation and follow-up are arranged through NHS neurology, neuropsychology and therapy teams. The NHS signposts Encephalitis International, the main support group in the UK, for information and support.