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Causes & Transmission

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Causes

Meningococcal disease is caused by the bacterium Neisseria meningitidis. About 1 out of 10 people have this type of bacteria in the back of their nose and throat with no signs or symptoms of disease; this is called being 'a carrier'. But sometimes Neisseria meningitidis bacteria can invade the body causing certain illnesses, which are known as meningococcal disease.

There are five serogroups (“strains”) of Neisseria meningitidis: A, B, C, W, and Y that cause most disease worldwide. Three of these serogroups (B, C, and Y) cause most of the illness seen in the United States.

Transmission

Meningococcal disease is spread from person to person. The bacteria are spread by exchanging respiratory and throat secretions (saliva or spit) during close (for example, coughing or kissing) or lengthy contact, especially if living in the same household. Fortunately, these bacteria are not as contagious as germs that cause the common cold or the flu. The bacteria are not spread by casual contact or by simply breathing the air where a person with meningococcal disease has been.

Sometimes Neisseria meningitidis bacteria spread to people who have had close or lengthy contact with a patient with meningococcal disease. People in the same household, roommates, or anyone with direct contact with a patient's oral secretions, such as a boyfriend or girlfriend, would be considered at increased risk of getting the infection.

People who qualify as close contacts of a person with meningococcal disease should receive antibiotics to prevent them from getting the disease. This is known as prophylaxis (pro-fuh-lak-sis). The health department investigates each case of meningococcal disease to make sure all close contacts are identified and receive prophylaxis. This does not mean that the contacts have the disease; it is to prevent it. People who are not a close contact of a patient with meningococcal disease do not require prophylaxis.

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