What Is Meningitis?

Medically reviewed by Brigid Dwyer, MD

Meningitis causes inflammation and swelling of the meninges, which are protective linings around the brain and spinal cord. Most cases of meningitis are caused by a viral or bacterial infection that makes its way into the cerebrospinal fluid (CSF) and triggers meningeal inflammation. However, other microorganisms and noninfectious causes can also result in meningitis.

Viral meningitis is caused by viruses like non-polio enteroviruses, herpes simplex virus, West Nile virus, or influenza (the flu). Bacterial meningitis is caused by bacteria such as Neisseria meningitidis (mengococcus), Streptococcus pneumoniae (pneumococcus), and Group B streptococcus (Group B strep).

Bacterial meningitis can be treated with antibiotics; viral meningitis won't benefit from antibiotic treatments but usually clears itself. A healthcare provider is needed to diagnose the type of meningitis and appropriate treatment.

Although bacterial meningitis is less common than the viral form, it's usually significantly more serious and more likely to be deadly.

This article will explore the different types of meningitis, its symptoms, how you get it, when it's contagious, vaccine options, how meningitis is treated, and when it's most likely to be fatal.

Types of Meningitis

Meningitis is grouped into these types:

• Viral meningitis: The most common viral cause in the United States is non-polio enteroviruses (such as echoviruses). Other viruses that cause meningitis include herpesviruses (Epstein-Barr virus, herpes simplex viruses, and the varicella-zoster virus that causes chickenpox and shingles), influenza virus, West Nile virus, mumps virus, and measles virus.

• Bacterial meningitis: The bacteria most often responsible for bacterial meningitis in the United States are Streptococcus pneumoniae, Group B Streptococcus, Neisseria meningitidis, Haemophilus influenza, Listeria monocytogenes, and Escherichia coli (E. coli).
  

• Fungal meningitis: This can develop from infection by Cryptococcus, Histoplasma, Blastomyces, Coccidioides, and Candida. People with a weakened immune system are at higher risk.

• Parasitic meningitis: Parasites from raw or undercooked food or the environment are a less common form of meningitis.

• Amebic meningitis (primary amebic meningoencephalitis): This is very rare in the United States, caused by infection by the single-celled organism Naegleria fowleri.

• Noninfectious meningitis (inflammation of the meninges not caused by infectious agents): Causes include cancer, systemic lupus erythematosus, medications, chemicals, head injury, and brain surgery.

Infants: Signs and Symptoms of Meningitis in Babies

Babies are at high risk of bacterial meningitis and often have symptoms that mimic other illnesses. Parents should be on the lookout for meningitis symptoms such as high fever, stiff neck, rigid extremities, vomiting, diarrhea, or a skin rash with lots of pinpoint-sized dots (petechiae) that are associated with invasive meningococcal disease.

How Do You Get Meningitis?

There are many different causes of inflammation of the meninges. You can get meningitis from viruses or bacteria, but sometimes inflammation of the meninges is caused by noninfectious factors like autoimmune diseases, medications, or neurosurgical procedures.

People more at risk of meningitis include babies, children, older adults, and people with compromised immune systems.

Is Meningitis Contagious?

Although inflammation of the meninges isn't contagious, specific microorganisms that cause different types of viral or bacterial meningitis can spread easily. Contagiousness depends on the type of meningitis.

For example, acute meningococcal disease caused by Neisseria meningitidis bacteria is highly contagious. The presence of this bacteria is monitored closely on college campuses and other communities where people live close together because it can cause outbreaks in clusters.

Notably, people can be asymptomatic carriers of meningitis-causing bacteria without ever developing meningitis. They don't get sick but can transmit the bacteria that causes meningococcal disease to others.

Amebic meningitis doesn't spread via person-to-person contact and isn't contagious. A warm-water-loving amoeba enters the body through the nose when someone is swimming or using infected water to clean their nasal passages.

How Is Meningitis Spread?

Viral and bacterial meningitis can spread via close contact with saliva, nasal secretions, respiratory droplets, and feces. For example, the bacterium that causes meningococcal meningitis is not as contagious as the common cold, but people in the same household are at elevated risk of getting sick.

Meningitis Symptoms

The most common meningitis symptoms include:

• Stiff neck

• Pounding headache

• High temperature

• Severe stomach ache

• Nausea

• Vomiting

• Sensitivity to light (photophobia)

• Dizziness

• Back pain

• Confusion

• Seizures or loss of consciousness

Less common symptoms include:

• Skin rash
  

• Fatigue

• Trouble waking from sleep
  

• Loss of appetite

• Difficulty concentrating
  

When to Seek Medical Attention for Meningitis

Anyone with meningitis symptoms should speak to a healthcare provider and seek medical attention immediately. Time is of the essence when it comes to meningitis. The faster people with bacterial meningitis start receiving appropriate treatment, the less likely they are to die.

What Are Meningitis Vaccines?

Vaccinations can help prevent both viral and bacterial meningitis.

Meningococcal vaccines (under the trade names Menactra, Menveo, MenQuadfi, Penbraya, Bexsero, and Trumenba) protect against bacterial meningitis caused by different strains of Neisseria meningitidis bacteria. Pneumococcal vaccines and Haemophilus influenzae b vaccine reduce the risks of meningitis caused by those bacteria.

Routine viral vaccines and immunizations can lower the risk of developing viral meningitis. These include vaccines for mumps, measles, and influenza.

In 2020, the Centers for Disease Control and Prevention (CDC) reported an increasing number of antibiotic-resistant cases of meningococcal disease in the United States. Vaccines are the best defense against multidrug-resistant organisms (MDROs) that are increasingly associated with fatal cases of bacterial meningitis.

Meningitis Tests

When someone has meningitis symptoms, a lumbar puncture (spinal tap) is often performed to extract CSF and test it to determine what's causing inflammation of the meninges.

Other tests used to determine what's causing someone's meningitis symptoms include:

• Cerebrospinal fluid (CSF) analysis, including white blood cell counts, protein, and glucose values

• Acid-fast bacilli (AFB) smear and culture

• Polymerase chain reaction (PCR)

• Cryptococcal antigen detection

• Nucleic acid amplification tests (NAATs)
  

Treatment for Meningitis

Different types of meningitis require different treatments. For example, oral antibiotics or intravenous antimicrobial agents (IV antibiotics) administered at a hospital are the first-line treatment for bacterial meningitis. Corticosteroids may be given to reduce inflammation, and anticonvulsants may be given to prevent seizures.

However, antibiotics don't work for people with viral meningitis. Fortunately, mild viral meningitis usually resolves itself in seven to 10 days without treatment in people who aren't immunocompromised. Antiviral medications may be used to treat viral meningitis caused by influenza or herpesvirus.

Intravenous antifungal agents may be used for fungal meningitis, such as cryptococcal meningitis. After IV treatment, a course of oral antifungal medications is given. For people with weak immune systems, treatment may be longer. One or more lumbar punctures may be done to check that the fungal culture is negative.

Always speak to a healthcare provider and seek medical attention at the first sign of meningitis symptoms. The sooner they determine if you have meningitis and, if so, what type, the faster you can start appropriate treatment.

Recovering From Meningitis

Most people make a full recovery from mild cases of meningitis. However, more severe cases can cause long-term disabilities or subsequent medical problems. It is important to continue any antibiotic, antiviral, or antifungal treatment for as long as recommended.

Complications of Meningitis

About 1 in 5 people with bacterial meningitis experience complications, including:

• Septicemia (bloodstream infection, which can also be the cause of meningitis)

• Language and communication issues

• Difficulty speaking

• Vision and hearing difficulties

• Seizures

• Amputation if clots form in small blood vessels in the skin and lead to tissue death (necrosis)

Outlook for Meningitis

Some types of meningitis are more serious than others and have a worse prognosis. For example, the outlook for someone with viral meningitis will be better than the outlook for someone diagnosed with bacterial meningitis. Viral meningitis tends to be milder and less fatal than meningitis caused by a life-threatening bacterium like Neisseria meningitidis.

Even with antibiotic treatment, 5% to 15% of people diagnosed with invasive meningococcal disease caused by N. meningitidis will die, and up to 20% of survivors experience long-term disabilities.

Vaccination to prevent viral and bacterial infections that can lead to meningitis has significantly reduced the incidence of some types of meningitis.

Summary

Meningitis is characterized by inflammation of the membrane that protects the brain and spinal cord. Anything that causes these membranes to swell is classified as meningitis.

Viral and bacterial meningitis are the two most common types. Viral meningitis is usually less severe than the bacterial form, but all meningitis infections should be treated as medical emergencies. Bacterial meningitis caused by Neisseria meningitidis progresses very rapidly and is especially dangerous; it leads to death in about 1 in 10 cases and can be fatal in just a few hours.

Antibiotics don’t work against viruses and can’t help people with viral meningitis. Luckily, most people with robust immune systems recover from viral meningitis without treatment. Antibiotics are used to treat bacterial meningitis.

Meningococcal vaccines and other vaccines against viruses and bacteria are everybody’s best defense against contracting meningitis.

Read the original article on Verywell Health.