Infections of the brain can be caused by viruses, bacteria, fungi, or,
occasionally, protozoa or parasites. Another group of brain disorders, called spongiform encephalopathies, are caused
by abnormal substances called prions.
Infections of the brain often also involve other parts of the central nervous system, including the spinal cord. The
brain and spinal cord are usually protected from infection, but when they become infected, the consequences are often