If you need to define a word in your paper, the definition usually comes from a glossary in the back of a book. To properly attribute this definition you will need to cite it according to the American Psychological Association (APA) style guidelines.
Encephalitis is inflammation of the brain tissue. It's most often caused by viral infections. In some cases, bacterial infections can also cause encephalitis.
Infectious agents that can cause encephalitis include bacteria, viruses, fungi, protozoans, and other parasites. Encephalitis can be caused by viruses like herpes viruses, enteroviruses, mumps, measles, and varicella viruses. Other organisms can also cause nonarboviral encephalitis.