Types of Meningitis
Meningitis is either infectious (contagious) or noninfectious. Infectious meningitis is classified as viral, bacterial, fungal, or parasitic, depending on the type of organism causing the infection.
Viral meningitis, also called aseptic meningitis, is the most common type. It is rarely fatal and usually resolves with treatment. Meningitis develops in fewer than 1 in 1000 people who are infected with one of the viruses associated with the condition.
Bacterial meningitis is often severe and is considered a potential medical emergency. If left untreated, bacterial meningitis may be fatal or cause serious long-term complications. Because bacterial meningitis can progress rapidly, it is important to identify the bacteria and begin antibiotic treatment as soon as possible.
Bacterial infection in the ears, mouth, or sinuses can spread directly to the brain and spinal cord. Some types of bacteria are transmitted from person to person through secretions from the mouth and nose.
Fungal meningitis develops in patients with conditions that compromise the effectiveness of their immune systems (e.g., HIV/AIDS, lupus, diabetes). Fungal meningitis occurs in 10% of patients with AIDS. Crytococcus neoformans and Candida albicans are commonly involved in fungal meningitis.
Parasitic meningitis is more common in underdeveloped countries and usually is caused by parasites found in contaminated water, food, and soil.
Noninfectious meningitis may develop as a complication of another illness (e.g., mumps, tuberculosis, syphilis). A break in the skin and/or bones in the face or skull (caused by birth defect, brain surgery, head injury) can allow bacteria to enter the body.
Rarely, meningitis can be caused by exposure to certain medications, such as the following:
- Immune globulin
- Levamisole (Ergamisole®)
- Metronidazole (Flagyl®)
- Mumps and rubella vaccines
- Nonsteroidal anti-inflammatory drugs (e.g., ibuprofen, diclofenac, naproxen)