The nationwide prospective questionnaire study of cases and controls was implemented during the period from October 1996 till May 1998. Thirty-nine districts participated (=54.2% of district hygiene stations) and 107 invasive meningococcal diseases were included in the study (=76.9% of diseases recorded during the given period in the Czech Republic by active surveillance). A total of 390 subjects were included in the study – 107 with invasive meningococcal diseases, 211 healthy controls and 72 healthy carriers of Neisseria meningitidis. This is the first study in the Czech Republic which analyzes comprehensively socioeconomic, health and stress factors in relation to the genesis and development of invasive meningococcal disease or carriership of N. meningitidis. The relationship between these factors and meningococcal disease or carriership was evaluated by the chi square test: odds ratio (OR) and statistical significance (p for chi square – Yates correction or Fischer’s exact test). For the development of invasive meningococcal disease in particular, risk factors are significant (p < 0.05) which at the time weaken the overall resistance of the organism: febrile diseases, respiratory diseases, other diseases, exertion, exposure to cold, mental stress, other stress, injury, staying in places outside the home on brigades, training courses, stay in crowded premises. As to long-term factors the development of the disease is influenced by a contaminated environment, passive smoking and lower education of the mother which indicates a different lifestyle. Conversely, factors negatively correlated with the development of the disease are active participation in sports and favourable economic conditions. For death: significant risk factors (p < 0.05) are also factors which weaken the resistance of the organism: exertion, mental stress, other stress (= alcohol consumption), staying outside the home on brigades, training courses etc. For carriership risk factors are significant (p < 0.05) when the mucosal membranes of the upper airways are impaired (staying in a dusty environment, in smoke-filled rooms, contaminated atmosphere, active smoking, passive smoking) and factors where contact with other people is frequent (overcrowded rooms, multi-generation housing, use of public transport, staying outside the home on brigades, training courses etc.). A risk factor is also lower education of parents which indicates a different lifestyle. Conversely, factors negatively correlated with carriership are favourable economic conditions, frequent outdoor stay and active participation in sports. By comparison of factors significantly associated with the development of invasive meningococcal disease or carriership data are assem- bled for the implementation of effective preventive measures.

        Key words: invasive meningococcal disease – carriership of Neisseria meningitidis – risk factors.