Neisseria meningitidis(N.meningitidis) is an exclusively human pathogen that has been identified in 10%-35% of the adult population and in 5.9% of the child population.Despite the high prevalence of carriers of N.meningitidis,it only occasionally causes meningococcal disease in the context of endemic disease,in certain geographic areas or in isolated epidemic outbreaks.After the N.meningitidis genome is described,progress has been made toward understanding the pathogenic mechanisms of the bacteria,although some aspects concerning its interaction with the environment and the host remain unclear.Some studies have reported that oxidative stress in the environment can modify the surface characteristics of N.meningitidis,increasing its adhesive properties and favouring an asymptomaticcarrier state.The antigenic structure of N.meningitidis can be modified by its importing genetic material from other bacteria in its ecological niche.Some structures of lipopolysaccharides help it to evade the immune response,and these are observed more frequently in N.meningitidis isolated from blood than in healthy nasopharyngeal carriers.There is evidence that pili and capsule are downregulated upon contact with target cells.This paper reviews current knowledge on hostenvironment-bacteria mechanisms and interactions,with the aim of contributing to our understanding of the pathogenic mechanisms of N.meningitidis. Neisseria meningitidis is an exclusively human pathogen that has been identified in 10% -35% of the adult population and in 5.9% of the child population. Ideally the high prevalence of carriers of N. meningitidis, it only occasionally causes meningococcal disease in the context of endemic disease, in certain geographic areas or in isolated epidemic outbreaks. After the N. meningitidis genome is described, progress has been made to understanding the pathogenic mechanisms of the bacteria, or some of the issues concerning its interaction with the environment and the host remain unclear.Some studies have reported that oxidative stress in the environment can modify the surface characteristics of N. meningitidis, increasing its adhesive properties and favoring an asymptomaticcarrier state. The antigenic structure of N. meningitidis can be modified by its Import genetic material from other bacteria in its ecological niche.Some structures of lipopolysaccharides help it to evade the immune response, and these are observed more frequently in N. meningitidis isolated from blood than in healthy nasopharyngeal carriers. There is evidence that pili and capsule are downregulated upon contact with target cells. This paper reviews current knowledge on hostenvironment-bacteria mechanisms and interactions, with the aim of contributing to our understanding of the pathogenic mechanisms of N. meningitidis.