The brain is surrounded and protected by the bones of the skull, cranial meninges, and cerebrospinal fluid.
Meningitis is the infection of the meninges, the membrane that surrounds the brain and spinal cord. The warm, dark environment of the meninges is an ideal breeding ground for a number of bacteria and viruses.
There are many different types of meningitis. Meningitis can be caused by fungi, chemical irritation or drug allergies, and tumors. Meningitis caused by viral infections usually resolves without treatment. However, bacterial infection of the meninges is an extremely serious illness that can result in death or brain damage even if treated appropriately.
One form of bacterial meningitis involves the bacteria that exist naturally in the upper respiratory tract of some people. Meningitis occurs when these bacteria leave the respiratory tract and travel through the bloodstream to the meninges.
Common symptoms of bacterial meningitis include vomiting and high fever; the more classic symptoms of meningitis are severe headache, neck stiffness, change in mental status and sensitivity to light.
It is possible for the bacteria that cause meningitis to multiply while in the bloodstream. The result is blood poisoning, called septicemia, which can cause a purple rash to develop on the body. Both bacterial meningitis and septicemia are considered medical emergencies and require immediate medical attention.
In the US, children routinely receive vaccinations to help prevent certain types of meningitis. College students who live in dormitories are particularly at risk and should consult their physician.