The meningococcus has occupied a special position among bacteria causing disease in humans. Epidemiologic data in this country, available since 1920 and reported by the Center for Disease Control (CDC), show that three major epidemics have occurred, with peaks in 1929, 1936, and 1943. At those times the case rate per 100,000 population was 8.6, 5.7, and 13.6, respectively.1 The most recent sizable epidemic occurred in the early 1950s, with a peak incidence of 3.2 cases per 100,000 population in 1953. In the ten-year period beginning in 1968, disease rates compiled by the CDC have ranged from a low of 0.64 per 100,000 population (1,323 cases in 1972) to 1.46 cases per 100,000 (2,951 cases in 1969). Both the reported total number of cases and rate have increased slightly since 1974.2
Like the revolving of an outer wheel, epidemics of meningococcal disease have come in waves or cycles.