Meningitis is the inflammation of the meninges (the membrane lining the brain and spinal cord). It usually refers to infections caused by viruses, bacteria, fungi, and other microorganisms such as parasites.

The most common form of meningitis is bacterial meningitis. It is life threatening and can cause death within hours, if not properly treated.

Some of the bacteria that cause meningitis can also cause septicaemia. This is an infection of the blood. The toxins released by the bacteria into the blood can cause damage to blood vessels and organs throughout the body. 

Some people develop meningitis or septicaemia. Other people develop both meningitis and septicaemia at the same time.

There are many types of meningitis including pneumococcal meningitis and meningococcal meningitis. Whilst the symptoms are similar for each, the causes, treatments and outcomes do vary.

Bacterial meningitis

The most common types of bacterial meningitis seen today are

• Pneumococcal meningitis
• Meningococcal disease (meningococcal meningitis and/or meningococcal septicaemia)

There are various strains of meningococcal meningitis, including strains A, B, C, W, and Y. The most common in New Zealand is meningococcal B. The second most common is meningococcal W.

Babies, young children, teenagers and young adults are at the greatest risk of infection. 

Some forms of bacterial meningitis affect new-born babies. The most common are E coli, group B streptococcus and Listeria. These types are rare outside of the neonate period (the first 28 days following birth).

The germs that cause bacterial meningitis are very common and live naturally in the back of the nose and throat of about 15% of the population. They can be spread between people by coughing, sneezing, kissing and sharing drinking bottles but they cannot live for more than a few seconds outside the body. Therefore they cannot be picked up from water supplies, swimming pools, or public places.

Other types of Meningitis

VIRAL MENINGITIS
Viral meningitis is an uncommon complication of some viral illnesses (e.g. herpes). Most cases are mild but more severe illnesses sometimes do occur. It is rarely fatal. No antibiotic treatment or vaccine is available for most viral meningitis.

AMOEBIC MENINGITIS 
Amoebic meningitis is a very rare infection. It is caught from stagnant water in waterholes and in poorly chlorinated swimming pools, especially when the water temperature rises above 30°C. Children can become infected when contaminated water is forced up the nose. The organism then reaches the base of the brain directly. Children should not be allowed to swim in poorly chlorinated swimming pools or stagnant waterholes, particularly on very hot days.

FUNGAL MENINGITIS
Some fungi can occasionally cause meningitis, but the disease is rare and usually occurs only in patients whose immune system has been severely depressed by disease, (e.g. AIDS, leukaemia, or as a result of drug therapy). Fungal meningitis may be slow and difficult to diagnose and treat.