[Occurrence of meningococcal meningitis in a Southern region of Brazil, from 1974 to 1980, using the point event model].

Descriptive statistical techniques and point event model methods were used to investigate the temporal series of cases of meningococcal meningitis which occurred in 100 municipalities in the Rio Grande do Sul State, Brazil, during the period 1974-1980. The data were grouped by epidemiological state (epidemic or endemic), and separated into 5 groups according to the municipal population. The number of cases of the disease notified weekly was analysed by means of incidence coefficients, with the purpose of studying the epidemic threshold for the state. The time interval between events was analysed in the light of their probability density functions and expected density functions, with the objective of studying the relationship and dependences among events. The analysis of the epidemic threshold suggests that there should not be only one threshold value for detection of outbreak of the disease throughout the state. Analysis of the expected density function extracted from inter-event intervals of the epidemic state showed a correlational structure indicating dependence between events occurring up to 14 weeks apart. No significant correlation for the endemic state, taking as reference model the shuffled version of the original intervals, was observed.