The meningitis bacterium lives harmlessly in the noses and throats of one in 10 people but,  for reasons that are not fully understood, can erupt into a  life-threatening illness  that causes inflammation of the membrane  around the brain – the “meninges” – and can lead to death within hours.

The bacterium can also enter the bloodstream, causing  meningococcal septicaemia, a devastating infection which leads quickly to organ failure and death and is marked by a distinctive purple rash on the skin.

Classic symptoms of meningitis include a headache, stiff neck and dislike of bright lights. Symptoms of septicaemia (blood poisoning) include leg pain, cold hands and feet, as well as a rash.

In the past 20 years, vaccines have been developed against haemophilus B meningitis, meningitis C and pneumococcal meningitis.

The meningitis B vaccine will dramatically increase protection but will still not cover against all forms.

Parents and individuals are advised to stay alert for signs and symptoms and seek medical help immediately if they suspect something is wrong.