Encephalitis is a viral infection of the brain and spinal cord. Two forms of this viral brain inflammation are rabies and poliomyelitis. There is no treatment for encephalitis, although many types of it can be prevented by immunization. Viruses that cause encephalitis may be epidemic, such as polio; or they may be sporadic, such as herpes simplex, varicella zoster, and mumps.

Diagnosis of encephalitis can be made by blood tests or by an EEG (electroencephalogram). However, since antiobiotics are not sufficient for curing viral infections, the treatment of encephalitis usually involves management of and relief from the symptoms of the disease. The body's immune system must fight the virus on its own.