What does encephalitis describe?

Encephalitis specifically refers to the inflammation of the brain, often due to an infectious agent, autoimmune response, or reaction to a toxin. The term derives from "encephalo," meaning brain, and "itis," which denotes inflammation. This condition can cause a variety of symptoms including fever, headache, confusion, seizures, and, in severe cases, neurological deficits or coma.

The other options pertain to entirely different medical conditions: infection of the lungs refers to pneumonia, swelling of the abdomen may indicate conditions such as ascites or organ enlargement, and infection of the heart can describe infective endocarditis. Each of these terms has its own specific definition and implications in the medical field, making it clear that encephalitis is distinct in its focus on brain inflammation.