It's one of the deadliest diseases, and also one medical experts have unanswered questions about.
It's believed 15 per cent of us carry the bacteria that causes meningococcal disease without ever getting sick. But for others, for reasons still not completely understood, this bacteria can go on to cause serious illness and death.
It's believed overcrowding is one of the main reasons why Māori and Pacific Island communities experience higher rates than any other ethnicity.
As we head into winter, when meningitis most commonly occurs, Ruwani Perera met with two whānau whose lives have been forever changed by what's known as "The Silent Killer".