Understanding meningitis - the basics

What is meningitis?

Meningitis is a relatively rare condition that affects the delicate membranes - called meninges - that cover the brain and spinal cord. Bacterial meningitis can be contagious among people in close contact with each other, such as in classrooms and university halls of residence.

Viral meningitis tends to be less severe and most people recover completely. Fungal meningitis is a rare form and generally occurs only in people with weakened immune systems.

What causes meningitis?

Meningitis is almost always caused by a bacterial or viral infection that began elsewhere in the body, such as in the ears, sinuses or upper respiratory tract. Less common causes of meningitis include fungal infection, immune system disorders and medications.

Bacterial meningitis

The bacterial form of meningitis is an extremely serious illness that requires immediate medical attention. If not treated quickly, it can lead to death within hours or to permanent brain damage.

Bacterial meningitis is caused by any one of several bacteria. Neisseria meningitidis, or “meningococcus”,  is common in young adults, and Streptococcus pneumoniae or “pneumococcus” is the most common form in adults. Haemophilus influenza  type b (Hib) was a common form in infants until the Hib vaccine was introduced for infants. Meningococcus and pneumococcus account for most of the bacterial meningitis cases in the UK.

Meningitis C vaccination reduces your risk of developing one of the forms of bacterial meningitis. It was introduced in November 1999 for everybody up to the age of 18 years, and to all first year university students. This has since been extended to include everybody under 25 years of age as well as anyone at increased risk of infection.

The bacteria can spread from person to person through coughing and sneezing.  If you are around someone who has bacterial meningitis, seek medical advice to ask if you need to take steps so you don’t become infected. In many instances, bacterial meningitis develops when bacteria get into the bloodstream from the sinuses, ears or other part of the upper respiratory tract. The bacteria then travel through the bloodstream to the brain.

Viral meningitis

Viral meningitis is more common than the bacterial form and generally, but not always, less serious. It can be triggered by a number of viruses, including several that can cause diarrhoea. People with viral meningitis are much less likely to have permanent brain damage after the infection resolves. Most will recover completely.

Fungal meningitis

Fungal meningitis is much less common than the other two infectious forms. Fungus-related meningitis is rare in healthy people. However, somebody who has an impaired immune system, such as a person with AIDS, is more likely to become infected with this form of meningitis.