Meningitis is an inflammation of the membranes that surround the brain and spinal cord. For the most part, this swelling and inflammation is caused by an infection. The majority of the time, meningitis is caused by a viral infection. However, bacterial and fungal infections can also lead to meningitis, as well as other non-infectious causes. Depending upon the cause, meningitis may resolve spontaneously or can become a life-threatening emergency.
Viruses
According to the Centers for Disease Control and Prevention, viral meningitis is usually less severe and will resolve without any specific treatment. Most cases are diagnosed during the summer months and are caused by enteroviruses. When individuals have other infections caused by viruses, they can also lead to meningitis Some of those infections include the mumps, Epstein-Barr, varicella-zoster, measles, influenza and, in rare cases, lymphocytic choriomeningitis virus. Both adults and children who suffer from enteroviral meningitis describe it as the worst headache they have ever experienced.
Fungal
According to physicians from MayoClinic.com, meningitis resulting from a fungal infection is relatively uncommon. Cryptococcal meningitis is a fungal form that more often affects individuals who have an immune-suppressing disease, such as AIDS. Fungal meningitis is life-threatening and must be treated as an emergency situation. Other fungi which may cause meningitis include candida, histoplasma and coccidioides.
Streptococcus Pneumoniae
For many years, Streptococcus pneumoniae was the primary bacterial cause of meningitis, but it is becoming less common now as individuals are routinely vaccinated against it. According to Merck Manuals Online Medical Library, Streptococcus pneumoniae is normally present in the external environment and reside in the nose and upper respiratory system of some people without ever causing harm. Occasionally, without an identifiable reason, these organisms can infect the brain and cause spinal meningitis. Individuals who suffer from certain chronic disorders that affect the heart, lungs, liver, kidneys or joints will have a higher risk of becoming infected. Use of corticosteroids or immunosuppressants, as well as a splenectomy, chronic infections of your nose or sinuses and sickle cell disease, will also place individuals at higher risk for developing meningitis from Streptococcus pneumoniae.
Neisseria Meningitidis
The Neisseria meningitidisis bacteria is another leading cause of bacterial meningitis, report the physicians at MayoClinic.com. Often called "meningococcal meningitis" because of the bacterial name, the infection is highly contagious and can cause local epidemics within populations of individuals who live in close quarters. These situations include college dormitories, boarding schools, child care centers and military bases. Meningococcal meningitis occurs when the bacteria from an upper respiratory infection enters the bloodstream and crosses the blood-brain barrier.
Listeria Monocytogenes
According to Merck Manuals Online Medical Library, this bacteria is a common cause of meningitis in newborns, pregnant women and individuals over the age of 50. People who have kidney or liver failure or who are taking corticosteroids and immunosuppressants will be at an increased risk of developing meningitis from this bacteria.
Other
Because meningitis is an inflammation of the meninges that surround the brain and spinal cord, that inflammation and swelling may also have a noninfectious cause. The Centers for Disease Control and Prevention reports that noninfectious meningitis can be the result of cancer, lupus, certain drugs, head injury and brain surgery. Treatment of meningitis in these cases originates with the treatment of the underlying cause.
