A meningitis test can diagnose meningitis, and help determine the cause of it. Tests may include a physical examination, blood tests and cultures, and imaging tests.

Meningitis occurs when the meninges, the protective coating around the brain and spinal cord, becomes inflamed. Because meningitis can be a life-threatening emergency, a person who thinks they may have meningitis should seek immediate medical care.

A cerebrospinal fluid (CSF) analysis can definitively diagnose meningitis. However, a doctor may recommend additional tests to rule out other causes.

If a doctor suspects bacterial meningitis, they may begin antibiotic treatment before meningitis test results come back.

Meningitis causes swelling and inflammation of the meninges. The meninges are three membranes that protect the brain and spinal cord.

Meningitis usually happens when an infection – often a virus or bacteria – travels to the meninges.

Less commonly, a fungus or parasite can cause meningitis. Bacterial meningitis can kill a person within a few hours without treatment, while viral meningitis often goes away on its own.

Very rarely, an amoeba called Naegleria fowlerican travel through water, up the nose, and into the brain. This type of meningitis is almost always fatal.

Meningitis can also occur without an infection, as a result of cancer or other diseases. Meningitis tests can tell a doctor which type of meningitis a person has, and guide treatment decisions.

This article explores the importance of seeking immediate medical attention to test for meningitis, types of tests and how doctors diagnose meningitis, meningitis causes, and the outlook for a person diagnosed with various types of the disease.

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Meningitis can be a life-threatening emergency, especially if a person has bacterial meningitis. Bacterial meningitis can kill a person in a few hours.

Outcomes for viral meningitis are usually better, and a person may recover on their own without treatment.

However, it is impossible to know which type of meningitis a person has without medical testing.

Though meningitis is very serious, prompt care can save lives.

Go to the emergency room or call a doctor immediately if a person has:

  • a stiff neck
  • a very intense headache
  • a high fever, especially following an illness such as the flu
  • sensitivity to light
  • an unexplained rash
  • seizures
  • vomiting
  • confusion

There are a number of different tests a doctor can perform to diagnose meningitis, depending on which type of meningitis they think a person may have. They include:

Physical examination

Meningitis testing usually begins with a physical exam, during which a doctor assesses how likely it is that a person has meningitis. A doctor may ask about any recent illnesses, all symptoms, and when any symptoms appeared.

A doctor may also perform physical tests to assess for inflammation of the meninges. Two specific tests are often used to help diagnose meningitis.

One test looks for what is known as the Brudzinski sign. During this test, a person lies on their back while a doctor flexes their neck upward and toward the chest. If this causes the person to flex their knees or hips, this suggests inflammation of the meninges, and may mean a person has meningitis.

The other test looks for what is called the Kernig sign. During this test, a person lies on their back. A doctor bends the knee toward the chest, then attempts to straighten the leg upward. If this is very painful or impossible, a person may have swelling in the meninges, suggesting meningitis.

Blood tests and culture

Meningitis testing also generally includes blood work, which can rule out some other potential causes of meningitis, such as sepsis.

Some blood test results, such as a very high white blood cell count, may help with diagnosing a severe infection, including meningitis.

A doctor may also order bloodwork to test for other issues, such as poisoning or dangerous changes in blood glucose.

High levels of the chemical procalcitonin can also help a doctor determine whether an infection is more likely to be viral or bacterial. High procalcitonin suggests a bacterial infection.

A blood culture, which tests the blood for certain organisms, may be able to detect some types of meningitis in the blood, including some forms of bacterial and fungal meningitis. This can help guide treatment, especially when a doctor needs to know which type of antibiotic to use for bacterial meningitis.

However, a blood culture cannot definitively diagnose or rule out meningitis. According to a 2017 American Family Physician article, just 62–66% of adults under 60 with bacterial meningitis had a positive culture. Among adults over 65, the figure was slightly higher, at 73%.

Cerebrospinal fluid test

The most reliable way to diagnose meningitis is with a lumbar puncture. During a lumbar puncture, a doctor inserts a long, thin needle in between two vertebrae in the lower back. This allows them to withdraw some cerebrospinal fluid (CSF), which is the fluid that cushions the brain and spinal cord.

The doctor then sends the CSF to the lab to analyze it for signs of infection. A CSF culture can usually detect the specific organisms causing meningitis.

When a person has viral or noninfectious meningitis, there are not usually organisms in the CSF. Instead, a doctor will look for slightly elevated protein levels and elevated white blood cell counts.

Imaging tests

For some people, a lumbar puncture may not be safe. This may include those with high pressure inside the skull, certain brain diseases, a history of stroke, and those with weak immune systems because of HIV or certain drugs.

A CT scan uses x-rays to take pictures of the brain and skull. This can help with detecting whether there is any increased pressure in the head that may make a lumbar puncture unsafe. A doctor may recommend proceeding to a lumbar puncture if the CT scan indicates it would be safe.

A CT scan, however, is not a fully reliable measure of pressure in the head. A doctor may recommend foregoing both the CT scan and the lumbar puncture and beginning treatment if there are other signs of meningitis.

At-home tests

No home tests can conclusively prove that a person does or does not have meningitis. Instead, anyone with symptoms of meningitis should seek immediate medical care. Some warning signs include:

  • a stiff neck
  • a very intense headache
  • a high fever, especially following an illness such as the flu
  • sensitivity to light
  • an unexplained rash
  • seizures
  • vomiting
  • confusion

Looking for Kernig or Brudzinski signs may provide evidence that a person has meningitis. However, it is easy to perform these tests incorrectly, especially without medical training.

Many different infections and diseases can cause meningitis. They include:

  • Viral meningitis: Viral meningitis happens when a virus, such as measles, mumps, or the flu, spreads to the meninges. Symptoms usually are less serious than other types of meningitis. Viruses that cause viral meningitis spread from one person to another.
  • Bacterial meningitis: Bacterial meningitis happens when a bacterial infection spreads to the meninges. Many organisms can cause this infection, but some common culprits include group B streptococcus and Haemophilus influenzae. A person can spread group B strep to a newborn when giving birth vaginally. The infections that cause bacterial meningitis can spread from one person to another.
  • Fungal meningitis: Fungal meningitis happens when a person contracts a fungal infection, often by inhaling spores from the environment. The infection can then spread to the meninges. Candida, a common fungal infection on the skin that can cause yeast infections or thrush, may also spread to the meninges, but this is rare.
  • Parasitic meningitis: Parasitic meningitis happens when a parasite gets into the meninges. This is uncommon but can happen when a person eats raw or contaminated food, or has contact with raccoon feces from soil.
  • Amebic meningitis: This rare and highly lethal type of meningitis happens when a bacteria that lives in the water travels up the nose to the meninges.
  • Non-infectious meningitis: This means that the meninges become swollen without an infection. This can happen when a person has a serious disease like lupus erythematosus, a head injury, a recent brain surgery, or cancer.

The outlook depends on the type of meningitis a person has.

Bacterial meningitis has a much higher fatality rate than viral meningitis. In 2010, overall, 14.3% of people with bacterial meningitis died. Factors such as age – being either very young or very old – and having a weak immune system can increase the risk of death.

Amebic meningitis has a death rate that is much higher. Of 34 infections reported to Centers for Disease Control and Prevention (CDC) between 2009 and 2019, just 3 people survived.

Among people who do survive meningitis, complications are common, especially when meningitis damages the neurological system.

A 2010 meta-analysis of children diagnosed with meningitis found the following complication rates after hospital discharge:

  • hearing loss: 6%
  • behavioral issues: 2.6%
  • cognitive challenges: 2.2%
  • motor skill problems: 2.3%
  • seizures: 1.6%
  • vision impairments: 0.9%

Early testing and prompt treatment for meningitis is critical to survival.

A person who thinks they might have meningitis should not delay care, and should be clear and specific at the emergency room about what symptoms they are experiencing.

A person should tell a doctor about any recent potential meningitis exposures, and request testing for meningitis immediately.