Aseptic meningitis is an illness characterized by headache, fever, and inflammation of the lining of the brain (meninges). Although it looks like bacterial meningitis, bacteria do not grow in cultures of the cerebrospinal fluid (fluid around the brain and spinal cord).

With aseptic meningitis a person has signs and symptoms of meningitis, but bacteria do not grow in culture. Many different things can cause aseptic meningitis including viruses, fungi, tuberculosis, some medications, and infections near the brain or spinal cord, such as epidural abscesses.

Coxsackie virus and echovirus, two members of a family of viruses called enteroviruses, account for about half the cases of aseptic meningitis. Other enteroviruses, herpes viruses, and mumps are additional causes. The rate of these enteroviral infections increases in the summer and early fall.

West Nile virus is a cause of aseptic meningitis that has recently spread across the United States. Usually, West Nile virus causes a self-limited (gets better on its own, without treatment) meningitis. Infrequently, it causes a more severe illness, which may include encephalitis (inflammation in the actual brain tissue) or paralysis similar to that seen in polio. These severe forms usually occur in elderly people or people with lowered immunity.

Enteroviruses are spread by hand-to-mouth contact and coughing. To a lesser extent, they also spread by contact with fecal matter. Mumps is spread by coughing or contact with secretions from the mouth and throat, with increased incidence in the spring.

Herpesvirus, both type 1 (herpes simplex or herpes labialis) and type 2 (genital herpes) can cause meningitis in children, especially infants. Chicken pox can also cause aseptic meningitis. Rabies virus causes inflammation of both the brain and meninges (meningoencephalitis). HIV can cause aseptic meningitis, especially soon after exposure (acute HIV syndrome).

Some fungi and mycobacteria can cause aseptic meningitis, although this is much less common. Certain medications can also cause aseptic meningitis, including antibiotics and some over-the-counter anti-inflammatory medications.

Risk factors for aseptic meningitis include exposure to someone with a recent viral infection, exposure to children in a day care setting, being a health care worker, or having a suppressed immune system .

• Headache
• Fever
• Stiff neck
• General discomfort, uneasiness, or ill feeling (malaise)
• Sore throat
• Nausea and vomiting
• Drowsiness
• Abdominal pain
• Chills
• Rash
• Muscle pain
• Confusion
• Abnormal sensitivity to light (photophobia)

For any patient with meningitis, it is important to perform a lumbar puncture (spinal tap), where a sample of spinal fluid (known as cerebrospinal fluid, or CSF) is obtained and sent to the lab for testing.

Tests may reveal the following:

• High or low white blood cell count in the blood
• High white blood cell count in spinal fluid (usually lymphocytes, a type of white blood cells)

Bacterial cultures of spinal fluid do not grow any bacteria. Other cultures or other special tests of spinal fluid may detect viruses, or other forms of infection.

Treatment is needed for fungal or mycobacterial causes of aseptic meningitis. Herpesvirus/varicella (chicken pox) virus can be treated with anti-viral medicines. Supportive treatment for non-infectious causes consists of pain medications and management of complications, if they occur.

No specific treatment is available for enteroviral aseptic meningitis.

Aseptic meningitis is usually a harmless disease, and people usually have full recovery in 5 to 14 days after symptoms start.

Fatigue and lightheadedness may persist longer in some people.

Encephalitis (infection of brain itself) may develop, though this is rare. Infection may last much longer in a person with a depressed immune system.

Call your health care provider if symptoms of aseptic meningitis occur.

Good hand washing, immunization (against mumps or chicken pox, for example), and other general good health measures may reduce the risk of developing an infection that can progress to meningitis.