I.

Introduction

Meningitis, inflammation of the meninges, the membranes that surround the brain and spinal cord. Meningitis may be caused by a physical injury, a reaction to certain drugs, or more commonly, infection by certain viruses, bacteria, fungi, or parasites. This article focuses on meningitis caused by viral or bacterial infection. In the United States viral meningitis is the most common form of the disease, while bacterial meningitis, which affects an estimated 17,500 people each year, is the most serious form of the disease. Most cases of both viral and bacterial meningitis occur in the first five years of life.