It shares symptoms with bacterial meningitis, the more serious type.
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"Meningitis" is a broad term that refers to the swelling or inflammation of the membranes that cushion the brain and spinal cord. It happens when an infection spreads to the fluid within those membranes, or "meninges" as they're called. Meningitis can be caused by many things, including bacteria, fungi, and parasites, but the most common type—viral meningitis—can be blamed on (you guessed it!) a virus, per the CDC.

"You get more cases of viral [meningitis] than you would bacterial," Claire Wright, evidence and policy manager for the Meningitis Research Foundation in the UK, tells Health. "But bacterial is the one that's really serious and severe because it carries the risk of fatality, which viral tends not to."

People with a mild case of viral meningitis can recover on their own at home in seven to 10 days, according to the CDC. With that said, it can cause the same symptoms as bacterial meningitis, which can be deadly, so it's important to see a doctor ASAP if you develop signs of this disease.

Here's what you need to know about viral meningitis, including causes, diagnosis, and treatment.

What causes viral meningitis?

According to the National Institute of Neurological Disorders and Stroke (NINDS), viral meningitis is most frequently caused by enteroviruses, a group of viruses that can enter the body through the mouth and make their way to the brain and surrounding tissues, where they multiply.

Enteroviruses are extremely common, causing about 10 to 15 million infections every year, per the CDC. Most of the time, enteroviruses cause no symptoms whatsoever, or only a mild illness (like the common cold). Enteroviruses can lead to viral meningitis, though.

"It's really quite rare, if you look at it in comparison to the common cold," says Wright. She adds that doctors aren't quite sure why a small minority of people will develop viral meningitis from an enterovirus, while the majority suffer from only cold symptoms.

Enteroviruses aren't the only cause of viral meningitis, though. According to the CDC, other viruses that can lead to meningitis include:

  • Mumps virus
  • Measles virus
  • Influenza virus
  • Arboviruses (viruses that spread from insects to humans), including the West Nile virus
  • Herpesviruses (including herpes simplex, Epstein-Barr, and varicella-zoster, the virus responsible for chickenpox and shingles).
  • Lymphocytic choriomeningitis

Anyone exposed to one of these viruses can contract viral meningitis. However, it tends to be more common among kids under the age of 5 and people with compromised immune systems, per the CDC.

What are the symptoms of viral meningitis?

According to the CDC, viral meningitis can cause symptoms like:

  • Fever
  • Low energy levels (lethargy)
  • Headache
  • Stiff neck
  • Light sensitivity (photophobia)
  • Sleepiness and difficulty waking up
  • Nausea and/or vomiting
  • Irritability
  • Low appetite

Though the symptoms of viral meningitis can sometimes look and feel like other illnesses, Dhanashri Miskin, MD, a neuroimmunologist with Jefferson Health in Philadelphia, explains how to help tell the difference.

"With meningitis, it's a severe headache; the headache is the overarching issue, rather than when you're sick with something else," Dr. Miskin tells Health. She warns that a headache that wakes you up from sleep, or worsens when you're lying flat, can be an alarming sign that there's too much pressure in the brain caused by the swollen meninges.

That pressure is also why viral meningitis can make your eyes sensitive to light and your neck so stiff that it's hard to move, adds Dr. Miskin.

Pounding head pain, combined with other viral meningitis symptoms, is a sign that you should see a doctor right away.

"Someone who normally doesn't get a headache, then suddenly has the worst headache of their life, and they're taking medication, and it maybe calms it down, but as soon as it wears off, it's back to what it was, and they can't keep anything down—at that point I would think that person needs to be evaluated in an emergency setting," says Dr. Miskin.

How is viral meningitis diagnosed?

To diagnose viral meningitis, doctors often use a lumbar puncture, or spinal tap, in which a needle is inserted into the lower spine and a small amount of cerebrospinal fluid is drawn for testing. 

"The spinal fluid is our main diagnostic test for being able to discern between bacterial and viral meningitis," says Marie Grill, MD, specialist in neuroinfectious diseases at the Mayo Clinic.

According to Dr. Grill, that fluid can allow a doctor to check for signs of a meningitis infection, including white blood cell count, glucose levels, and the presence of bacteria or viruses known to cause the disease.

"We can also do a special antibody testing for things like West Nile virus and other viruses that are carried by mosquitoes that really allows us to be able to confirm the diagnosis," Dr. Grill tells Health.

How do doctors treat viral meningitis?

Meningitis treatment depends on which type of the disease a person has (hence why it's important to get a diagnosis from a doctor). Even though viral meningitis generally isn't life-threatening, bacterial meningitis can lead to death or long-term disabilities like brain damage and deafness. Both types cause similar symptoms.

Because of that, Dr. Grill says that patients presenting with symptoms are treated for both viral and bacterial meningitis until their lab results come in. "We start antibiotics that would cover for different bacteria, and then we also start an antiviral while we're waiting for the results of the fluid to come back," she says.

When a case is confirmed, viral meningitis treatment typically involves drinking plenty of fluids, taking over-the-counter medications to reduce fever and aches, and resting, according to the Mayo Clinic.

"The majority of viral meningitis cases are self-limited, so that means we address them with supportive treatments," says Dr. Grill.

If a case of viral meningitis was caused by certain herpes viruses, a doctor may also prescribe antiviral medication, she adds.

The exception, she says, is certain herpes viruses, which can be treated with antivirals.

According to Penn Medicine, viral meningitis symptoms usually disappear within a couple of weeks and cause no long-term complications.

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