Mode of Transmission Transmission can occur through direct contact including airborne droplets from nose and throat of infected persons. Transmission by fomites is insignicant. It is commonly three to four days, but can vary from two to 10 days. It is communicable until the organisms are no longer present in discharges from the nose and mouth. Susceptibility and Resistance Susceptibility to clinical disease is low as evidenced by the usual high ratio of carriers to cases.
Susceptibility decreases with age.
However, a secondary peak of meningococcal meningitis occurs in adolescents and young adults in the age group of 15 to 24 years. Patients decient in certain complement components in the blood are prone to recurrent meningococcal infections. There is an increased and prolonged risk of secondary infections in close contacts. In one series, the incidence of such infection was 0.5 per cent with a median interval of seven weeks between the index and secondary cases. Secondary cases have been reported up to ve months later.