Meningococcal infections are not common, but people die from it during most outbreaks. In 2002, a massive outbreak occurred in central Africa that sickened 13,000 people and killed 1,500. There have been sporadic outbreaks in the United States, especially in college dormitories. Over 3,000 cases of meningococcal infection were reported annually in the United States, most of which came from ten to fifteen outbreaks in various parts of the country. Ten to 15 percent of the infected people end up dying from the infection, despite prompt and appropriate treatment with antibiotics and other medications.

Meningitis caused by meningococcus used to make up only a small percentage of bacterial meningitis, but since the Hib and pneumococcal conjugate vaccines are working so well to prevent these other causes of meningitis in children, meningococcal meningitis is fast becoming the most common cause of meningitis in children.

Meningitis is most common in the winter season, and young infants are most commonly affected. The meningococcus bacterium is unique because it is the only type of bacterium that is capable of causing outbreaks of meningitis. Other bacterial meningitis usually does not involve outbreaks.