However in relation to the OP’s question about asymptomatic carriers of the disease:
All types of the disease can be transmitted by direct contact between individuals through saliva and nasal secretions. Incidence is highest in the winter months, due to the greater frequency of upper respiratory tract infections, closer personal contacts, and lack of indoor ventilation. 5 The literature reports that between five and twenty percent of the general population carry the meningococcal bacteria in the nose and throat in a relatively harmless state.5,10,14 This means 500 million out of six billion people of the world are “carriers”. The rate is highest in adolescents and young adults.17 These carriers may harbor the bacteria for days or months, yet may never develop the disease. Carriage can aid in immunity in some individuals. In certain instances, however, the bacteria break through the body’s immune defenses and travel to the fluid around the brain, the blood stream, or both. They enter the bloodstream and travel to the meninges, inflaming them and causing meningitis or multiply uncontrollably in the bloodstream, releasing toxins causing blood poisoning or septicaemia. The fatality rate in this form of the disease is two to four percent, while it reaches twenty percent with septicaemia.5 The speed of the progression of blood poisoning can be frightening, which explains the higher fatality rate. During epidemics of bacterial meningitis, the carrier rate may reach 95%, yet less than 1% may ever develop the disease.
Roughly 5%-10% of the population carries the meningococcal bacteria in the back of their nose and throat. The bacteria can be dormant in the carrier, but they can pass it to someone else. Bacterial meningitis is spread through the exchange of respiratory and throat secretions (kissing, coughing, sneezing, and sharing a cup, utensil, lip gloss, or cigarette). The transfer of saliva must be direct because the bacteria can’t live outside of the mouth. People with weaker immune systems are at a greater risk of contracting bacterial meningitis.