Meningococcal disease describes infections caused by the bacterium Neisseria meningitidis. Since the early 1990s, outbreaks of meningococcal disease have occurred with increasing frequency in the United States.
Neisseria meningitidis has become a leading cause of bacterial meningitis in the United States. In fact, Streptococcus pneumoniae and Neisseria meningitidis are today the leading causes of bacterial meningitis. It carries a high mortality rate if untreated.