1.Occurrence
Meningococcal disease occurs worldwide in both endemic and epidemic form.
2.Reservoir
Humans are the only natural reservoir of meningococcus. As many as 10% of adolescents and adults are asymptomatic transient carriers of N. meningitidis, most strains of which are not pathogenic (i.e., strains that are not groupable).
3.Transmission
Primary mode is by respiratory droplet spread or by direct contact.
4.Temporal Pattern
Meningococcal disease occurs throughout the year, however, the incidence is highest in the late winter and early spring.
5.Communicability
The communicability of N. meningitidis is generally limited. In studies of households in which a case of meningococcal disease has occurred, only 3%-4% of households had secondary cases. Most households had only one secondary case. Estimates of the risk of secondary transmission are generally 2-4 cases per 1,000 household members at risk. However, this risk is 500-800 times that in the general population.