The meninges (say: meh-NIN-jeez) cover and protect the brain and spinal cord. Meningitis happens when the meninges swell or get irritated.
Meningitis usually is caused by germs, especially viruses but sometimes bacteria. Someone with meningitis might get very sick with a bad headache, stiff neck, and fever. Meningitis also can affect the person's ability to think and learn. But many people recover from the infection without lasting problems.