Bacterial meningitis is aggressive, develops quickly and can lead to permanent disability or death in a matter of hours.
It is fatal in approximately 50% of cases and accounts for around 170,000 deaths around the world each year.
There are different types of meningococcus (called serogroups ), of which serogroups A, B, C, Y and W135 are responsible for over 95% of meningitis and septicaemia cases.
Septicaemia (blood poisoning) is a potentially life-threatening infection that occurs when the bacteria that cause meningitis get into the bloodstream. The infection may be seen alone or in addition to meningitis.
It is believed that 10-20% of the population carries the meningitis bacteria at any one time, but it will only develop into the disease in susceptible people.
The infection spreads from person to person through respiratory droplets (kissing, coughing, sneezing, sharing food or utensils). Children who attend day-care or preschool are at greater risk of contracting bacterial meningitis.
Viral meningitis is the most common but least severe type. Almost all patients recover without any permanent damage, although full recovery can take many weeks.
It is most often spread through respiratory droplets (kissing, coughing, sneezing, sharing food or utensils) or faecal contamination. Elderly people and those with conditions that affect their immune system are more at risk.
There are no vaccines available for viral meningitis, but washing hands thoroughly and keeping surfaces clean can help prevent the disease.
Fungal meningitis causes severe infections but occurs much less frequently. It is not contagious and spreads by inhaling fungal spores from the environment.
It is also possible to contract meningitis from parasites or through non-infectious means like cancers, lupus, certain drugs, head injuries, brain surgery, or an existing condition of the skull or spine.