Meningococcal disease, also referred to as cerebrospinal meningitis is a contagious bacterial disease caused by the meningococcus (Neisseria meningitidis).
It is spread by person-to-person contact through respiratory droplets of infected people. There are 3 main clinical forms of the disease: the meningeal syndrome, the septic form and pneumonia. The onset of symptoms is sudden and death can follow within hours. In as many as 10-15% of survivors, there are persistent neurological defects, including hearing loss, speech disorders, loss of limbs, mental retardation and paralysis.
N. meningitidis inhabits the mucosal membrane of the nose and throat, where it usually causes no harm. Up to 5-10% of a population may be asymptomatic carriers. These carriers are crucial to the spread of the disease as most cases are acquired through exposure to asymptomatic carriers. Waning immunity among the population against a particular strain favours epidemics, as do overcrowding and climatic conditions such as dry seasons or prolonged drought and dust storms. Smoking, mucosal lesions and concomitant respiratory infections are considered risk factors that may contribute to the development of the disease. The disease mainly affects young children, but is also common in older children and young adults.
The disease occurs sporadically throughout the world with seasonal variations and accounts for a proportion of endemic bacterial meningitis. However, the highest burden of the disease is due to the cyclic epidemics occurring in the African meningitis belt.