Different viruses, bacteria and fungi can all cause meningitis.
Viral meningitis, also called aseptic meningitis, is most common. It is usually less serious and is rarely life threatening. Viral meningitis infections occur most often in the summer and fall when the primary causes are most prevalent. There are no preventions for viral meningitis at this time, but people who are infected usually recover completely within 5 to 10 days.
Bacterial meningitis is a serious disease, which progresses very quickly. From a mild, flu-like beginning, it can be fatal within 48 hours or less. Suspected cases of bacterial meningitis require immediate medical attention. See Symptoms. Survivors can suffer severe consequences associated with brain damage: blindness, deafness, paralysis and mental retardation. Bacterial meningitis occurs most often - but not always - in winter. Safe and effective vaccines are available for the main causes.
Fungal meningitis is rare but can be serious. It occurs most often in people whose immune system is weakened by AIDS, cancer, diabetes, immune suppressing drugs following organ or bone marrow transplant, and other disorders. It may also occur in premature babies with very low birth weight. Fungal meningitis is treatable with anti-fungal drugs.