Meningitis is an infection and swelling, called inflammation, of the fluid and membranes around the brain and spinal cord. These membranes are called meninges. The inflammation from meningitis most often triggers symptoms such as headache, fever and a stiff neck. Viral infections are the most common cause of meningitis in the United States. Bacteria, parasites and fungi also can cause it. Sometimes meningitis improves in a few weeks without treatment. But meningitis also can cause death. It often needs quick treatment with antibiotics. Seek medical care right away if you think that you or someone in your family has meningitis. For meningitis caused by bacteria, early treatment can prevent serious complications.