What Are the Different Types of Meningitis?

Meningitis is inflammation or infection of the meninges and cerebrospinal fluid (CSF). Meninges are three layers of protective tissue surrounding the brain and spinal cord. CSF is a special fluid between the layers of the meninges that nourishes the brain. 

According to the World Health Organization (WHO), the worldwide incidence of meningitis is approximately 82 million cases per year. The Centers for Disease Control and Prevention (CDC) estimates that over 1.2 million cases of bacterial meningitis (a dangerous type of meningitis) occur worldwide each year.

Meningitis Symptoms 

Meningitis usually causes nonspecific symptoms, but sometimes it can cause focal neurological symptoms (those that affect a specific function or part of the body). 

Common symptoms of meningitis include:

• Fever
• Headaches
• Stiff neck
• Fatigue and lethargy
• Photophobia (a sense of discomfort when looking at light)
• Nausea and vomiting
• Dizziness 
• Back pain 
• Confusion
• Sleepiness or trouble waking up from sleep

A petechial rash that looks like clusters of tiny purplish dots on the skin can occur with bacterial meningitis, especially meningococcal meningitis.

Less commonly, meningitis can cause symptoms suggestive of brain involvement, including:

• Face, arm, or leg weakness or sensory changes on one side of the body 
• Vision changes 
• Hearing loss
• Seizures

Generally, viral meningitis and noninfectious meningitis cause mild to moderate generalized symptoms but can progress to severe symptoms and complications.

Bacterial meningitis may cause rapidly worsening generalized or focal symptoms, with a high risk of complications. Fungal, parasitic, and amebic meningitis are not common and may cause focal symptoms and/or seizures. 

Complications 

If meningitis is not adequately treated, it can lead to severe acute illness that requires intensive treatment. And sometimes meningitis leads to long-term problems, such as permanent hearing loss or cognitive deficits.

Types of Meningitis 

There are several types of infectious and noninfectious meningitis. They have different risk factors, anticipated outcomes, treatments, and complications. 

Meningitis can be diagnosed based on symptoms and physical examination, and brain imaging studies can show signs of inflammation of the meninges. The specific type of meningitis and infectious organism can be identified with a lumbar puncture (LP), which is an invasive test.

Viral Meningitis 

Viral meningitis is the most common type of meningitis. It can be caused by viruses that are commonly contagious in the community, including enterovirus, mumps virus, herpes simplex virus, varicella zoster virus (which normally causes chickenpox), Epstein-Barr virus, and West Nile virus.

You can develop viral meningitis as a complication of an infection with any of these viruses, although most people who contract them do not. Anyone can develop viral meningitis, but it is more common among children. Sometimes it is diagnosed clinically, without an LP.

People who have a healthy immune system usually recover quickly from viral meningitis, but it can cause complications, especially among people who have immune problems. People who have meningitis caused by a virus can transmit the virus to others, but those people are not likely to get meningitis as a result.

Bacterial Meningitis 

Bacterial meningitis is the second most common type of infectious meningitis, and it can be dangerous. The most common causes are Streptococcus pneumonia, Neisseria meningitidis, Haemophilus influenzae, Listeria monocytogenes, and group B Streptococcus. These organisms are prevalent in the environment and are contagious.

Meningococcal meningitis caused by N. meningitidis is especially associated with outbreaks among clusters of people who live in close quarters, such as in dorms or bunk rooms.

The symptoms can progress rapidly, and treatment should be targeted to the infectious organism. Generally, the bacteria is identified with an LP. Anyone can develop bacterial meningitis, but it is more common among people who have an impaired immune system or who have had brain surgery or head trauma.

Fungal Meningitis 

Fungal meningitis is not a common condition, and a weak immune system is a leading risk factor. Fungal meningitis can be caused by Candida (which is normally present on the skin), Cryptococcus, Histoplasma, Blastomyces, and Coccidiodes.

The organisms that can cause fungal meningitis are prevalent in the community. It is common to come into contact with them, but they normally do not cause infections in healthy people.

Parasitic Meningitis 

Parasites can invade the body, with exposure due to contamination from food that isn't fully cooked or from the environment. According to the CDC, the most common parasites that cause meningitis are Angiostrongylus cantonensis, Baylisascaris procyonis, and Gnathostoma spinigerum.

Parasitic infection can cause brain inflammation, and it may also appear like a mass or a growth in the brain. Parasites can reproduce after invading the body, or they may die and remain in the body, continuing to produce a mass effect in the brain. It is treated with antimicrobials, and the organism may be removed surgically.

Amebic Meningitis 

Amebic meningitis is very rare. Amoeba is a type of single-celled organism that usually lives in freshwater, lakes, rivers, soil, or contaminated sewer water. Organisms that can cause amebic meningitis include Naegleria fowleri and Acanthamoeba species.

Because the condition is rare, it may not be easily recognized, and brain imaging studies may identify a pattern of inflammation.

Amebic meningitis is often described as meningoencephalitis because the infection and inflammation affect the brain in addition to the meninges. Symptoms may progress, and complications can occur if the condition worsens.

Treatment may include a combination of antimicrobials that are usually used to treat fungal infections, as well as surgical treatment for fluid pressure in and around the brain.

Noninfectious Meningitis 

Inflammation of the meninges and CSF can occur without an infection. Sometimes referred to as aseptic meningitis, this can occur due to autoimmune diseases like lupus, sarcoidosis, or rheumatoid arthritis.

Not everyone who has these autoimmune conditions will develop associated meningitis. When it does occur, meningitis due to autoimmune disease will typically be infrequent and may cause fatigue, trouble concentrating, or confusion. 

Noninfectious meningitis can also occur as a result of medications or radiation to the brain, which is used to treat cancer. 

Cancer is a more serious cause of noninfectious meningitis. It can lead to leptomeningeal carcinomatosis, which is the spread of cancer cells throughout the meninges surrounding the brain and spinal cord. This complication of cancer may be treated with intrathecal chemotherapy, which is injected into the CSF.

Risk Factors 

Meningitis can affect anyone, but certain risk factors may make it more likely. Noninfectious meningitis is more common among people who have underlying associated conditions, such as sarcoidosis.

Having a weak immune system, such as due to HIV infection or immunosuppressive therapy, is a major risk factor for infectious meningitis.

Immunosuppressive therapies, such as steroids and more targeted drugs, are often prescribed to prevent organ rejection in people who have had an organ transplant, or they may be prescribed to manage chronic inflammatory or autoimmune disease. Chemotherapeutic medications used to treat cancer also cause immunosuppression.

Complications of meningitis are more likely if the condition is not treated. Additionally, having an impaired immune system can predispose someone to worsening meningitis, with an increased risk of long-term effects.

Prevention 

There are several ways to prevent meningitis, and the most well-established preventive strategy is vaccination. The condition is more common in areas of the world where vaccination rates are low.

Vaccines that can prevent meningitis include ones that protect against:

• Pneumococcus
• Chickenpox
• Haemophilus influenzae
• Measles
• Mumps
• Neisseria meningitidis

These vaccines are routinely recommended on a standard vaccination schedule in the U.S. Of these, the vaccines for N. meningitidis specifically aim to prevent meningitis:

• The MenACWY meningococcal conjugate vaccine (Menactra or Menveo) is recommended for all at age 11 to 12 years, with a booster at age 16, and for any children or adults who have a greater risk of meningococcal disease. This vaccine protects against four serogroups of the bacteria.
• The MenB serogroup B meningococcal vaccine (Bexsero or Trumenba) is recommended for teens and young adults (especially at age 16 through 18), or anyone age 10 or older who has a greater risk of meningococcal disease. It is given in addition to the MenACWY vaccine to add protection to serogroup B.

Even if you are vaccinated against organisms that cause meningitis, it is possible to develop the condition. Avoiding infection is important for your overall health and can reduce your chances of meningitis.

Strategies for preventing meningitis include:

• Handwashing, especially before eating and after using the toilet
• Avoiding contact with people who have an infection (even if the infection isn't meningitis)
• Keeping your immune system healthy by getting enough sleep, eating fresh food, and staying active
• Talking to your healthcare provider about extra precautions you need to take if you are immunosuppressed

And, if you develop symptoms of meningitis, seek medical attention right away. Prompt treatment can help you avoid complications.

A Word From Verywell

Being diagnosed with meningitis can be scary. Most of the time, meningitis resolves with supportive medical treatment, such as fever control, pain control, hydration, and anti-inflammatory medication.

Some types of meningitis require anti-microbial treatment and more extensive interventions, including ventricular shunt placement. With timely treatment, you can experience a good recovery after meningitis.