Testing for meningitis can include various tests, including a physical exam, blood tests, bacterial cultures, and cerebrospinal fluid tests.

Meningitis happens when the membranes, or meninges, around your spinal cord and brain become swollen from inflammation.

Four types of meningitis are possible:

  • Bacterial: The most severe and life-threatening form of meningitis. This type can be fatal if it’s not treated immediately with antibiotics to prevent the spread of the infection and further complications.
  • Viral (aseptic): The most common cause of a meningitis infection. This type usually isn’t as serious as bacterial meningitis and often goes away without requiring treatment.
  • Fungal: This uncommon type is caused by a fungus that gets into your spinal cord from your bloodstream.
  • Parasitic: This much less common form of meningitis is caused by parasites.

You don’t always need treatment for nonbacterial meningitis. The infection may clear up on its own. Meningitis can be mistaken for the flu, dehydration, or gastroenteritis. It can also be overlooked because symptoms may be mild or not always apparent.

Seek emergency medical attention if you notice any symptoms of meningitis. You should also contact your doctor if someone close to you at home or work has been diagnosed. Watch out for these symptoms:

  • having severe neck stiffness with no apparent cause
  • experiencing a constant, painful headache
  • feeling disoriented
  • feeling sick and throwing up
  • running a high fever (101°F and higher), particularly with the above symptoms

Early treatment, within 2 to 3 days (less than 1 day is recommended), can help prevent long-term or severe complications. Bacterial meningitis can quickly become deadly or cause brain damage in a few days without antibiotics.

Your doctor will conduct a full physical examination as the first step in looking for signs of meningitis.

First, your doctor will ask you about your symptoms, your medical history, and whether you’ve been on any recent trips to regions with a higher rate of certain types of meningitis.

Then, your doctor will check your entire body for any unusual markings, signs, or lumps. A purplish or reddish skin rash that doesn’t get lighter or disappear when you press against it can be a sign of severe infection with one of the types of bacteria that causes meningitis.

Your doctor may also look for two specific signs of a meningitis infection:

  • Brudzinski’s sign: Your doctor will pull your neck forward slowly. Neck stiffness and involuntary bending of the knees and hips can indicate meningitis.
  • Kernig’s sign: Your doctor will flex your leg at the knee and bend the leg forward at the hip. Then, they’ll slowly straighten your leg. Intense pain in your back or thigh can indicate meningitis. Your doctor may repeat this test on both legs.

However, more recent research shows that many people with meningitis doesn’t display these signs. A negative result on either of these tests doesn’t rule out the possibility of meningitis.

To take a bacterial culture, your doctor will collect a blood sample through a needle in a vein in your arm. The blood is transferred to small dishes known as petri dishes. Bacteria or other microorganisms can grow and become more abundant in these nutrient-rich dishes.

After a certain period of time (usually a few days), your doctor can look at the bacteria through a microscope and diagnose the specific bacteria causing an infection in the blood.

Your doctor can also put a sample on a microscope slide and stain it so that the bacteria are easier to see under a microscope. The results of this test may come back earlier than those from a culture.

To do a blood test for signs of meningitis, a technician inserts a needle into a vein in your arm and draws out a sample of your blood to send to a lab for testing.

A complete blood count (CBC) or total protein count check for heightened levels of certain cells and proteins that can suggest a meningitis infection.

A procalcitonin blood test can also help your doctor tell if an infection is more likely caused by either bacteria or a virus.

Blood tests may also be done at the same time as a spinal tap to compare the levels of cells, antibodies, and proteins and confirm the diagnosis.

An imaging test, such as computerized tomography (CT) scan, allows your doctor to take detailed images of your head and chest to look for signs of brain and spine inflammation associated with meningitis and help confirm a diagnosis.

A CT scan, in addition to magnetic resonance imaging (MRI) and X-ray imaging tests, can also help your doctor notice other things that can cause severe symptoms of meningitis, such as:

  • internal bleeding (hemorrhage)
  • fluid buildup in tissue (abscess)
  • swelling of the brain

These conditions may make it dangerous or impossible for your doctor to perform a spinal tap, so imaging tests are typically done before your doctor decides whether to do a spinal tap.

This is the only test that can truly diagnose meningitis. To perform this test, your doctor inserts a needle into your spine in order to collect cerebrospinal fluid (CSF) that’s found around your brain and spinal cord. Then, your doctor sends your CSF to a lab for testing. Meningitis is often confirmed when your CSF fluid has:

  • low levels of sugar (glucose)
  • high levels of white blood cells
  • high levels of blood protein
  • heightened level of antibodies responding to infection

A CSF test can also help your doctor figure out what type of bacteria or virus caused your meningitis.

Your doctor may also request a polymerase chain reaction (PCR) test. This test can analyze your CSF fluid for antibodies that increase in number during viral infections to decide what treatment will work best.

In theory, it’s possible to do the Brudzinski and Kernig tests at home to check for meningitis. However, you should still see your doctor for a diagnosis. These tests need to be performed by a professional — and even then they aren’t reliable as a sole method of diagnosis.

Remember that meningitis can be dangerous. Even if you could diagnose it at home, you wouldn’t be able to determine which type you have, and some types are life-threatening. Get emergency medical help if you have these symptoms:

  • neck stiffness
  • constant, painful headache
  • feelings of disorientation
  • vomiting or nausea
  • high fever (101°F and higher)

Here’s how to do the Brudzinski test at home:

  1. Lie flat on your back.
  2. Gently and slowly push on the back of your neck so that your head moves forward. For better results, have someone do this for you.
  3. Note if your hips and knees flex involuntarily as you raise your head. This is a positive Brudzinski sign, meaning that you may have meningitis.

And the Kernig test:

  1. Lie flat on your back.
  2. Lift your leg up at the hip and bend your knee to a 90-degree angle.
  3. Gently and slowly lift your leg up at the knee.
  4. Note if your back or thigh starts to hurt. This is a positive Kernig sign, meaning that you may have meningitis.

Always see your doctor for a diagnosis.

The different types of meningitis have different causes:

  • Bacterial meningitis happens when bacteria pass through your blood into the CSF. Bacteria can also get into your meninges and infect them directly. Bacteria can be spread through infected blood.
  • Viral (aseptic) meningitis happens when a virus gets into your CSF from your bloodstream. This can be caused by many types of viruses, such as the herpes virus, HIV, West Nile virus, and enteroviruses.
  • Fungal meningitis happens when a fungus, such as Cryptococcus, gets into your meninges or CSF from your bloodstream. It’s most common in people who have weak or compromised immune systems from cancer or HIV.
  • Parasitic meningitis happens when a parasite gets into your meninges or CSF from the bloodstream. It’s often caused by eating or drinking something that’s been contaminated by an infectious parasite that normally only infects animals.

Bacterial meningitis needs to be treated right away or it may result in severe complications, such as brain damage, or become deadly.

Seek emergency medical attention if you think you have a bacterial meningitis infection. Early and effective treatment can save your life and reduce your chance of complications.

Other causes may go away after a few days without treatment. See your doctor as soon as you can if you suspect that you have a meningitis infection caused by a virus or parasite.