Causes and Spread to Others

Couple hugging

Causes

Bacteria called Neisseria meningitidis cause meningococcal disease. About 1 in 10 people have these bacteria in the back of their nose and throat without being ill. This is called being ‘a carrier’. Sometimes the bacteria invade the body and cause certain illnesses, which are known as meningococcal disease.

There are six serogroups (types) of Neisseria meningitidis — A, B, C, W, X, 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.

Spread to Others

People spread meningococcal bacteria to other people by sharing respiratory and throat secretions (saliva or spit). Generally, it takes close (for example, coughing or kissing) or lengthy contact to spread these bacteria. Fortunately, they are not as contagious as germs that cause the common cold or the flu. People do not catch the bacteria through casual contact or by breathing air where someone with meningococcal disease has been.

Sometimes the bacteria spread to people who have had close or lengthy contact with a patient with meningococcal disease. Those at increased risk of getting sick include:

  • People in the same household
  • Roommates
  • Anyone with direct contact with the patient’s oral secretions, such as a boyfriend or girlfriend

Close contacts of someone with meningococcal disease should receive antibiotics to help prevent them from getting the disease. Experts call this prophylaxis (pro-fuh-lak-sis). This does not mean that the contacts have the disease; it is to prevent it. Health departments investigate each case of meningococcal disease to identify all close contacts and make sure they receive prophylaxis. People who are not a close contact of a patient with meningococcal disease do not need prophylaxis.

Page last reviewed: May 31, 2019