Surveillance of notifiable diseases is carried out by all physicians and laboratory scientists in both the hospital and private sectors. The system is overseen by the Departmental Directorates of Health and Social Affairs (DDASS) and coordinated by the Institute for Public Health Surveillance (InVS). The purpose of the DO is to prevent the risk of epidemics and to analyze trends in these diseases over time in order to adapt public health policies to the needs of the population. This document presents a detailed analysis of the situation regarding invasive meningococcal infections in the Midi-Pyrénées region based on DO data, along with a comparison to data from metropolitan France in 2006. (R.A.)