Types of Meningitis

Meningitis is a disease that develops from infection with an external pathogen. Less common is the non-infectious form. Let's see what their types are and how they are treated.

Meningitis is a disease that causes inflammation of the meninges and that manifests in different ways. The meninges are protective membranes that line the brain and spinal cord. Millions of cases are reported annually worldwide, with an estimated 318,000 deaths. Knowing about the different types of meningitis is important as a prevention protocol, and so we’ll show you all the different ways it can manifest itself.

How many types of meningitis are there?

The disease is classified according to the pathogen that triggered it. Most cases are mild and treatable, although if the diagnosis is postponed or medical assistance isn’t sought, complications that put the patient’s life at risk can occur. The United States Centers for Disease Control and Prevention (CDC) distinguish the following types of meningitis.

Viral meningitis

As Johns Hopkins Medicine reminds us, viral meningitis is the most common manifestation. It’s also the mildest form, and there aren’t many complications during its evolution.

According to the researchers, between 85% and 95% of the cases of this variant are due to enteroviruses. Other pathogens identified by the evidence include the following:

• Human parechovirus
• Human herpes 1 and 2
• Varicella-zoster virus
• Epstein-Barr virus
• Influenza
• Arboviruses (especially West Nile virus, Eastern equine encephalitis virus, and La Crosse virus)

Those who are infected by these viral particles can develop meningitis, although most of the time they don’t cause any complications. These are more common in certain population groups, such as children under 5 years old, people over 65 years old, and those with compromised immune systems.

There’s no standard treatment for this variant, so, most of the time, specialists choose to monitor the course of its evolution. In some settings, when complications arise, the patient may be hospitalized.

Bacterial meningitis

Bacterial is the second most common type of meningitis, although, compared to the previous one, it’s considered rare. It’s linked to greater complications and, if it isn’t treated properly, it can be fatal.

The World Health Organization (WHO) identifies the following bacteria among its most common catalysts:

• Streptococcus pneumoniae
• Haemophilus influenzae
• Neisseria meningitidis

N. meningitidis is the culprit in meningococcal meningitis, which is associated with potential epidemics. Of the 12 identified serogroups of the bacteria, 6 of these can generate outbreaks. It’s most common in infants, school-age children, and young people.

Other bacteria, such as Escherichia coli, Enterobacter, Klebsiella, Pseudomonas aeruginosa and Listeria monocytogenes can also cause it, according to the researchers. In this case, there’s a standard treatment: the use of antibiotics.

Fungal meningitis

Cases of fungal meningitis are considered rare, although a couple of thousand are reported each year worldwide. Evidence indicates that they develop as a result of infections in other parts of the body, such as the lungs.

The CDC highlights the following microorganisms:

• Histoplasma
• Cryptococcus
• Coccidioides
• Blastomyces
• Candida

Some of these can live inside the human body or on the skin without any major problems, although they do cause complications in patients with compromised immune systems. They’re treated with antifungal drugs, administered intravenously, or orally.

Parasitic meningitis

Parasitic meningitis usually develops when people consume infected animals. The most common parasites are Angiostrongylus cantonensis, Baylisascaris procyonis, and Gnathostoma spinigerum.

Most cases are reported in Southeast Asia, although infection is also possible in western countries. This variant is treated with antimicrobials and, in some settings, it’s possible to proceed surgically to remove the parasites.

Amoebic meningitis

Amoebic meningitis is a very rare manifestation that often causes life-threatening complications. Also called primary amoebic meningoencephalitis, it’s caused by Naegleria fowleri.

According to studies, this amoeba is more common in soils or fresh water in places with an average temperature of 30 degrees Celsius. So. the infections are restricted to some specific areas of the planet.

Only a couple of cases are reported a year and there’s no standard treatment to deal with it. The CDC indicates that in the United States, between 2009 and 2019, 34 patients were diagnosed, of which there were only 3 survivors. Its diagnostic process is also complex, in part due to the lack of knowledge of its evolution and development.

Non-infectious meningitis

Finally, we find non-infectious meningitis. Although most episodes can be explained based on the above types of meningitis, in some cases the inflammation occurs without any external infectious catalyst. That is, it’s a symptom of an underlying condition.

According to Boston Clinical Trials, the main culprits are head injuries, lupus, and cancer. Rheumatoid arthritis and sarcoidosis can also cause it.

How to prevent types of meningitis

Although not all types of meningitis can be prevented, there are vaccines that protect against most of the pathogens listed. The Meningitis Research Foundation recommends starting immunization cycles from 2 months of age, especially in areas where epidemics are more likely.

Part of its prevention also consists of cooking food well, washing hands, sanitizing objects that are frequently touched, avoiding drinking water that hasn’t been treated and limiting interaction with animals. Exercising, eating a balanced diet, and keeping diagnosed illnesses under control are also helpful.

In turn, you should go to a medical center as soon as you notice the symptoms. The prognoses are in your favor if you start treatment during the early stages.