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What causes encephalitis?

Dr. Jeanne Morrison, PhD
Family Practitioner

A viral infection in the brain is the most common cause of encephalitis. Sometimes the viral infection starts in another part of the body and then spreads to the brain. Measles and the herpes virus are two common viral infections have been known to cause encephalitis. Encephalitis may also be brought on by a bacterial infection, although this is less common. Lyme disease is one example of a bacterial infection that has been linked to encephalitis.

Infectious encephalitis occurs when viruses, bacteria, fungi or parasites get into the brain. Usually the body's immune system protects the brain by fighting off these germs. But sometimes the germs are too strong and the immune system can’t fight them off. The germs multiply and attack the brain. This makes the brain swell up and stops it from working properly. This is infectious encephalitis.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.