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how many strains of meningitis are there

There isn’t one single fixed number, because “meningitis” is a syndrome that can be caused by many different germs and conditions, but we can group the main types and then the key strains people usually mean when they ask this.

Core answer: how many “strains”?

When people say “how many strains of meningitis are there?”, they’re usually talking about the major infectious causes doctors focus on, especially bacterial meningitis.

1. Big “types” of meningitis

First, by cause, there are six widely recognised types:

  • Viral meningitis
  • Bacterial meningitis
  • Fungal meningitis
  • Parasitic meningitis
  • Amebic meningitis
  • Non‑infectious meningitis (e.g., due to drugs, cancer, autoimmune disease)

Each of these types can be caused by multiple organisms (and therefore many “strains”), so the true count runs into dozens or more if you list every microbe one by one.

2. Main bacterial strains people usually mean

For everyday and vaccine discussions, most doctors focus on a smaller set of high‑impact bacterial causes and their main strains:

  • Meningococcus (Neisseria meningitidis) – major serogroups/“strains”:
    • A, B, C, W, Y (and in some regions also X)
  • Pneumococcus (Streptococcus pneumoniae) – more than 90 serotypes exist, but vaccines cover a selected subset (e.g., 10, 13, 15, 20, or more depending on vaccine).
  • Haemophilus influenzae type b (Hib) – the classic strain that used to be a leading cause in children before Hib vaccination.
  • Group B Streptococcus (Streptococcus agalactiae) – particularly important in newborn and young‑infant meningitis.
  • Other neonatal bacteria, such as E. coli and Listeria monocytogenes, are also important but not usually counted as “meningococcal strains.”

So if you’re thinking specifically of “meningococcal strains” (meningitis caused by Neisseria meningitidis), there are five main disease‑causing serogroups worldwide: A, B, C, W and Y , with X also recognised in some regions.

If instead you mean “how many types of meningitis overall?”, there are six broad types by cause , and within those, many individual organisms and strain variants.

Mini sections

Why this feels confusing

  • “Meningitis” describes inflammation of the membranes around the brain and spinal cord, not a single germ.
  • Each germ has multiple serogroups/serotypes/strains, so scientists count far more categories than patients usually hear about.

A bit like “flu”: there are many flu strains, but most people only hear about a few main ones each season.

What matters practically

For most people, the most important “strain” information is:

  1. Which meningococcal serogroups (A, B, C, W, Y ± X) circulate where you live.
  2. Which vaccines you have (e.g., MenACWY, MenB, pneumococcal, Hib, sometimes others).
  3. Age and risk factors (babies, teenagers, people in crowded housing, some immune problems).

If you tell me your country/region and age group, I can outline which meningitis strains and vaccines are most relevant for you. Information gathered from public forums or data available on the internet and portrayed here.