What Is the Infectious Agent of Meningitis?

According the the Meningitis Foundation of America, meningitis is an infection of the cerebrospinal fluid (CSF) of a person's spinal cord and the fluid that surrounds the brain. The infectious causes of meningitis include bacteria, viruses, fungi and parasites.

Bacterial Causes

• The most common causes of bacterial or purulent meningitis include Beta strep group B, particularly in the newborn; Neisseria meningitidis in teens and young adults; and Streptococcus pneumoniae in adults. Bacterial meningitis is more serious than viral meningitis and can have serious after-effects such as brain damage and hearing loss. Untreated bacterial meningitis can be fatal.

Viral Causes

• Viral or aseptic meningitis is typically a self-limiting infection and resolves without treatment. The enteroviruses are the viruses most commonly implicated. Less frequently seen are the mumps virus, herpes simplex virus and influenza viruses, among others.

Fungal Causes

• The rare but potentially fatal type of infectious meningitis caused by fungi is usually seen in patients with a compromised immune system because of AIDS or on immunosuppressive drugs. The yeast Cryptococcus neoformans and the mold Histoplasma capsulatum are two of the more common causes.

Parasitic Causes

• The nearly always fatal amoeba, Naegleria fowleri, is the cause of primary amoebic meningoencephalitis. You can get infected by swimming, jumping or playing in freshwater and get the water up your nose. The parasite travels to the brain and spinal cord and necrotizes or basically eats brain tissue.

Treatment

• Antibiotics are available and effective for treating bacterial causes of meningitis; however, it is critical to start it quickly. Long courses of anti-fungal medication can be used to treat fungal infections. There is not a specific drug treatment for aseptic meningitis, and the infection resolves on its own in about a week.

Prevention/Solution

• Many causes of bacterial meningitis can be prevented by vaccination. Since the introduction of the Haemophilus influenzae B vaccine, what was once a common cause of meningitis is now rare. Meningitis is often spread through respiratory droplets so avoiding close contact can decrease your risk. Hand washing is the key to preventing just about every contagious disease, including meningitis.