Definition: Strains of Neisseria meningitidis responsible for most outbreaks of meningococcal disease in Western Europe and the United States in the first half of the 20th century. They continue to be a major cause of disease in Asia and Africa, and especially localized epidemics in Sub-Sahara Africa.
infection: coord IM with MENINGITIS, MENINGOCOCCAL (IM) or, if not meningitis, MENINGOCOCCAL INFECTIONS (IM)
Other names Meningococci, Serogroup A; Meningococcus, Serogroup A
