Meningitis is usually caused by a viral or bacterial infection.

Viral meningitis is the most common and least serious type. Bacterial meningitis is rare, but can be very serious if not treated.

Several different viruses and bacteria can cause meningitis, including:

• meningococcal bacteria – there are several different types, called A, B, C, W, X, Y and Z
• pneumococcal bacteria
• Haemophilus influenzae type b (Hib) bacteria
• enteroviruses – viruses that usually only cause a mild stomach infection
• the mumps virus
• the herpes simplex virus – a virus that usually causes cold sores or genital herpes

A number of meningitis vaccinations provide protection against many of the infections that can cause meningitis.

The viruses and bacteria that cause meningitis can be spread through close contact with a person who has them.

This can include:

• contact with the person's spit, such as kissing them, or sharing drinks or vapes
• being in close contact with the person for a lot of time, such as living in the same home

The infection is usually spread by people who carry these viruses or bacteria in their nose or throat but are not ill themselves.

The infection can also be spread by someone with meningitis, although this is less common.

It's possible to get meningitis more than once.

Anyone can potentially get meningitis, but it's more common in:

• babies and young children
• teenagers and young adults
• older people
• people with a weak immune system – for example, those with HIV and those having chemotherapy

You can reduce the risk of getting meningitis by ensuring all your vaccinations are up to date.

Find out more about meningitis vaccinations