N. meningitidis is a common inhabitant of the mucosal membranes of the nose and throat, where it usually causes no harm. A small minority of the persons who contract the disease will develop an acute inflammation of the meninges, the membranes covering the brain and the spinal cord. The disease is mainly affecting young children, but is also common in older children and young adults. There are two clinical forms of meningococcal disease. Meningococcal meningitis is the more common entity, especially during epidemics, and the less common entity is meningococcal septicaemia.
Meningococcal meningitis is the only form of bacterial meningitis which causes epidemics.
The data presented in this report refer to both clinical forms of meningococcal disease. Meningococcal disease occurs as both an endemic and epidemic disease, and both forms cause substantial illness, and death, as well as persistent neurological defects, particularly deafness. Other consequences of the disease are loss of limbs, mental retardation and paralysis. Because of the severe consequences of meningococcal disease, access to treatment with antimicrobials as early as possible is very important. In the case of epidemics, mass vaccination campaigns are used to control epidemics.