Encephalitis comes from the Greek enkephalos meaning brain and itis meaning inflammation. The effects of Encephalitis can range in severity from having little or no long term results to being life-threatening. Children and adults of both sexes and all ethnic groups can be affected at any age. It is thought that the annual incidence in the UK and Republic of Ireland is 4 in 100,000 or two thousand five hundred people per year.

Encephalitis is usually caused by a viral infection. Exposure to viruses can occur through insect bites, food or drink contamination, inhalation of respiratory droplets from an infected person, or skin contact. Common illnesses such as measles and mumps can lead to Encephalitis. The virus reaches the brain causing an infection. Infected nerves may become damaged or destroyed. Although viruses infecting the brain are a major cause of encephalitis, the body's reaction to a virus itself can lead to encephalitis. This occurs when the immune system tries to fight off the virus and by mistake, attacks the nerves in the brain at the same time. This condition is called Post Infectious or autoimmune Encephalitis.

Symptoms of Encephalitis include:

• Fever or flu-like illness;
• Headache;
• Vomiting;
• Light-sensitivity of the eyes;
• Stiff neck and back (occasionally);
• Confusion, disorientation;
• Behaviour that is out of character;
• Drowsiness;
• Clumsiness, unsteady gait.

More serious acute symptoms that require immediate investigation include:

• Loss of consciousness, poor responsiveness, stupor, coma;
• Seizures;
• Muscle weakness or paralysis.

A diagnosis of Encephalitis is made following a range of tests which can include:

• Lumbar puncture in which the cerebrospinal fluid is tested for viral particles, especially herpes simplex virus. These tests can also exclude bacterial meningitis;
• Brain scans (CT or MRI) - to exclude brain tumours, aneurysms and strokes and show the extent of any inflammation;
• An electroencephalogram (EEG) will help confirm a diagnosis of encephalitis by recording any unusual patterns of electrical activity in the brain.

It should be noted that it is not unusual for the results of some tests to be "normal". It is important to initially exclude some more common and treatable diseases.

An antiviral medication, Acyclovir, will be prescribed. Acyclovir has significantly improved the outlook in cases of herpes simplex encephalitis but is not as effective against other viruses. Steroids may be prescribed for Post Infectious encephalitis. Other treatment for Encephalitis is symptomatic.

Provision of nutrition, fluids and rest will allow the body to fight the infection. Emotional support of agitated or confused persons is helpful.

After the acute phase of Encephalitis, which may last from one to two weeks, physiotherapy and speech therapy may be necessary and an assessment by a neuropsychologist is advised.

A proportion of people will be left with highly variable and often permanent consequences of the illness (acquired brain injury). These difficulties may include cognitive, physical, emotional or behavioural consequences. Specialist clinical support and rehabilitation are needed to help the person adjust to, and cope with, such difficulties.

Specific forms of Encephalitis include Acute Disseminated Encephalomyelitis, Rasmussen's Encephalitis, Hashimoto's Encephalitis, Subacute-Sclerosing Panencephalitis, West Nile Encephalitis, Japanese encephalitis and Tick-borne encephalitis.

Inheritance patterns
None.

Prenatal diagnosis
None.

Medical text written November 2005 by the Encephalitis Society and Contact a Family. Approved November 2005 by Professor Hawkins, Professor of Clinical Neurology, Keele University and Consultant Neurologist to the Regional Neuroscience Centre, Stoke-on-Trent, UK.

Further Online Resources
Medical texts in The Contact a Family Directory are designed to give a short, clear description of specific conditions and rare disorders. More extensive information on this condition can be found on a range of reliable, validated web sites and links to them are included in the CD-ROM version of this Directory. Further information on these resources can be found in our Medical Information on the Internet article.

ENCEPHALITIS SOCIETY

Encephalitis Society
Encephalitis Resource Centre
7b Saville Street
Malton
YO17 7LL
Tel: 01653 699599    
Fax: 01653 604369
e-mail: mail@encephalitis.info
Web: http://www.encephalitis.info

The Society is a National Registered Charity No. 1087843, established in 1991. It offers support and contact by telephone, e-mail, letter and linking with other families where possible. The Society publishes a newsletter three times a year and two books specifically for families with children affected by encephalitis: 'Encephalitis - a parents handbook' and 'Gilley the Giraffe ...who changed', a storybook for children. It also produces a comic strip for teenagers. The Society has around 800 members. Each year the children's home page receives over 40,000 web hits and the society responds to approximately 100 child related enquiries.

Group details last confirmed August 2007.