Mode of Transmisson
Meningococcal bacteria are transmitted from person to person by respiratory droplets (sneezing and coughing) or by direct contact with secretions from mouth and nose (e.g., kissing or sharing a glass).
Nasopharyngeal colonization occurs first, resulting in a carrier state, and is followed by penetration of the bacteria through the mucosa. Carriage may be facilitated by crowded living conditions, smoking and passive smoke inhalation, or concurrent viral infections. Increased meningococcal disease has been reported in the past following epidemics of influenza A.
As a result of attaching to the host's cells, antibodies are slowly induced so that adults can become protected even when exposed to a person suffering from an acute infection. For unknown reasons, only a small fraction of carriers develop meningitis. People with underlying immune deficiencies appear to be at an increased risk of recurrent meningococcal disease.
Neisseria meningitidis is a fragile organism, susceptible to cold and drying. It cannot survive more than a few seconds outside the body. Under normal circumstances, it is not transmitted in water supplies, swimming pools, or by routine contact in classrooms, dining rooms, rest-rooms, etc., where an infected individual has been. However, after intimate or direct exposure (sharing eating utensils, being touched or kissed, or droplet contamination from nose, throat, or any other body secretion or excretion) to a meningococcal meningitis patient within seven days after he or she was infected, the risk for contracting the disease is high. In this case prophylactic treatment with antibiotics should be initiated.
The question of why one individual develops invasive disease after a contact with N. meningitidis, whereas hundreds of others acquiring the same strain do not, still remains unsolved.
Before the use of serum therapy and the discovery of sulfonamides and other antibiotics, meningococcal disease was fatal in about 70% of cases. Today, despite an increased understanding of its pathogenesis and appropriate treatment, the mortality rate still ranges between 7 and 20% and for septicemia, between 18 and 53%, particularly if untreated or diagnosed too late.
Due to increasing resistance to modern antibiotics, the high rate of complications, the frequently rapid course, as well as the high mortality rate despite adequate treatment, prevention by vaccination has become a topic for health professionals all over the world. Vaccines against meningococcal serotypes A and C are available globally and their continued use saves lives around the world.