Meningococcal disease is an important cause of morbidity and mortality worldwide. It is a contagious disease caused by the Gram-negative diplococcus Neisseria meningitidis that is divided in at least 12 serogroups. Transmission occurs by direct contact or droplets from the nose or throat (sneezing or coughing) of infected persons. It is the only form of bacterial meningitis that causes epidemics. Even in countries with well organized health care systems 5-10% of patients die of meningococcal disease and about 20% of survivors will suffer severe neurological dysfunctions, including deafness, palsies, seizures, and mental disorders.