What are the differences between encephalitis vs encephalopathies?

Fever. Encephalitis is a state of altered mental status associated with fever as well as certain findings on brain imaging and lumbar puncture. Encephalitis is often caused by an infection (bacterial, viral, parasitic) but can be due to autoimmune diseases. Encephalopathy is an altered mental status without fever that can be due to many different causes including drug effects, lack of oxygen and toxins.