A type of meningitis caused by the bacterium Neisseria meningitidis. Bacteria are transmitted by coughing and sneezing: outbreaks occur most commonly in overcrowded conditions and children are more susceptible than adults. After an incubation period of 3-5 days, symptoms appear suddenly, including severe headache, fever, stiffness of the neck muscles, and a rash of small red spots on the trunk. Occasionally the disease enters a chronic state in which deafness, blindness, and serious mental deterioration may occur. Without treatment death can occur within a week, but administration of penicillin or sulfonamide drugs is usually effective.