How does meningococcal disease occur?
Approximately 10% of the general population carry meningococcal bacteria in the nose and throat in a harmless state. This carrier state may last for days or months before spontaneously disappearing, and it seems to give persons who harbor the bacteria in their upper respiratory tracts some protection from developing meningococcal disease. During meningococcal disease outbreaks, the percentage of people carrying the bacterium may approach 95%, yet the percentage of people who develop the meningococcal disease is less than 1%. This low occurrence of disease following exposure suggests that a person’s own immune system, in addition to bacterial factors, plays a key role. Meningococcal bacteria cannot usually live for more than a few minutes outside the body. As a result, they are not easily transmitted in water supplies, swimming pools, or by routine contact with an infected person in a classroom, dining room, bar, rest room, etc. Roommates, friends, spouses, and children who have had int
