Most important source of infection for meningococci:
During periods of endemic disease, about 10% of the general population harbour Neisseria meningitidis in the nasopharynx. 
Since N. meningitidis is a strict human pathogen and most patients have not been in contact with other cases, asymptomatic carriers are presumably the major source of the pathogenic strains.
Case
Subclinical infection
Carriers
Latent case