Various infections and conditions can lead to inflammation of the protective layers around the brain and spinal cord.

The central nervous system (CNS), made up of the brain and spinal cord, manages almost all bodily functions. It's surrounded by a protective fluid called cerebrospinal fluid and layers of membranes called meninges. When these membranes become inflamed or swollen, the condition is called meningitis.

Symptoms can include a severe headache, neck stiffness, fever, and sensitivity to light. Meningitis can result from infections, injuries, or even certain medications. Understanding the different types is important for identifying causes and receiving proper treatment.

1. Viral Meningitis

This is the most common and often the least severe form. It’s usually caused by enteroviruses—viruses that typically cause mild illnesses. Other viruses linked to viral meningitis include:

  • Herpes simplex virus (especially type 2)
  • HIV
  • Influenza virus
  • Mumps virus
  • Varicella zoster virus (which causes chickenpox and shingles)

Viral meningitis is often spread through contact with infected individuals or contaminated surfaces. It typically resolves on its own, with treatment focused on rest, fluids, and pain relief.

2. Bacterial Meningitis

This type is more dangerous and can become life-threatening if not treated promptly. It can lead to serious complications such as hearing loss, seizures, or brain damage.

One of the most severe forms is pneumococcal meningitis, caused by the Streptococcus pneumoniae bacteria—the same bacteria responsible for pneumonia. Immediate medical attention is essential, and treatment generally involves strong intravenous antibiotics and sometimes corticosteroids.

3. Fungal Meningitis

Fungal meningitis is rare and typically affects individuals with weakened immune systems. It occurs when a fungal infection elsewhere in the body spreads to the CNS.

The most common fungus involved is Cryptococcus neoformans, found in the environment. While it's generally harmless for healthy people, it can be serious for those with conditions like cancer or HIV.

4. Parasitic Meningitis

This type is caused by parasites and is uncommon in most parts of the world, especially in the U.S. One specific form, eosinophilic meningitis, may result from parasites such as Angiostrongylus cantonensis.

Contaminated food—like undercooked snails, freshwater fish, or frogs—can be sources of infection. Though rare, parasitic meningitis can be serious and requires targeted treatment.

5. Amebic Meningitis

A very rare but deadly form, this is caused by free-living amoebas such as Naegleria fowleri. Infection can happen when contaminated water enters the nose—often during swimming or diving in warm freshwater lakes or poorly maintained pools.

This type of meningitis progresses quickly and is often fatal if not diagnosed and treated right away.

6. Non-Infectious Meningitis

Unlike the types above, non-infectious meningitis doesn’t result from an infection and isn’t contagious. Instead, it's caused by factors such as:

  • Certain cancers (e.g., leukemia, lymphoma)
  • Autoimmune diseases like lupus or Sjogren’s syndrome
  • Reactions to medications, including some antibiotics and NSAIDs
  • Head injuries or brain surgery

Although symptoms can be similar to infectious meningitis, treatment depends on addressing the underlying cause.

Summary

Meningitis refers to inflammation of the protective membranes around the brain and spinal cord. Causes range from viruses and bacteria to fungi, parasites, and non-infectious factors like medications or autoimmune conditions. Proper diagnosis is crucial since treatments vary widely depending on the type. If you experience signs of meningitis, seek medical attention promptly.