(CNN)Here's a look at meningitis outbreaks in the United States.
Meningitis is caused by the inflammation of the protective membranes (known as meninges) covering the brain and spinal cord. The inflammation is typically caused by an infection of the fluid surrounding these areas.
Bacterial meningitis is contagious and comes in a number of different strains.
Viral meningitis is less severe and occurs more frequently than bacterial meningitis.
Fungal, viral, parasitic and non-infectious meningitis are not contagious, and do not spread from person to person.
Fungal and parasitic meningitis are rare.
The most common causes of meningitis are viral infections, when a virus travels to the brain after entering the system through the nose or the mouth.
Bacterial meningitis starts with an infection similar to a cold and spreads via respiratory and throat secretions, like saliva and phlegm.
People contract fungal meningitis by inhaling affected spores.
Contamination of food, water and soil can lead to parasitic meningitis.
Non-infectious meningitis can be caused by physical injury, cancer, systemic lupus and certain drugs.