Meningococcal Meningitis with Particular Reference to Epidemiology and Pathogenesis.

In this country cerebrospinal meningitis (fever) is an endemic disease found mainly in children and adolescents; local outbreaks occur, but they are rare and usually involve few individuals. The disease has, however, a marked predilection for war-time conditions; relatively extensive outbreaks occurred during the 1914-18 war, and again to an even greater extent during the 1939-45 war. These outbreaks involved individuals of all ages, including Service personnel, but it is interesting to note that, even though there was a great increase in the total number of cases notified, these tended to occur singly and an epidemic, in the generally accepted sense, did not develop. Although such general factors as the enhanced virulence of the meningococcus and the resistance of the individual are well recognized as playing an important role in the epidemiology of the disease, a precise explanation of the peculiar nature of the outbreaks is still lapking. A popular theory is that outbreaks of cerebrospinal meningitis result from a widespread meningococcal infection of the nasophayhx in the general population (Ministry of Health Memorandum, 1940). Many workers accept the hypothesis developed by Dopter (1921) that meningococcal infection occurs in three progressive stages: (1) catarrhal, (2) septicaemic, and (3) meningitic; in the majority of cases the infection is arrfsted at the catarrhal stage and the occurrence of meningitis is a rare phenomenon (Lundie and others, 1915; Herrick 1918; Murray, 1929; Brinton, 1941). The evidence offered to support this hypothesis is, however, inconclusive and unconvincing. Furthermore this theory does not provide a solution of many problems presented in the various outbreaks, and it seemed desirable that the question should be re-examined in the light of information gained during the 1940-42 outbreak. During the past seven years an opportunity has been available of studying the disease under Service and civilian conditions during both so-called epidemic and interepidemic periods and it was possible to direct attention particularly to the epidemiology and pathogenesis of the disease. The results are discussed below; they do not support the above hypothesis and an alternative is offered.