[Current situation of the epidemiology of meningococcal disease].

Neisseria meningitidis, the etiological agent of all forms of meningococcal disease, is still a cause for concern among society in general and especially among health workers. Several of its antigens have been used in strain characterization, and some have served as the basis for the development of vaccines. In this sense, the best known are the capsular polysaccharide, which defines the serogroups, the outer membrane protein of class 2/3, used for serotype classification, and the class 1 porins, defining the serosubtype. During the last 30 years, most cases of meningococcal disease in Spain have been due to serogroup B strains, with the exception of 1996 and 1997, when serogroup C cases became the most frequent. The capsular polysaccharide has been successfully used in the development of conjugate vaccines highly effective against A, Y and W135 serogroups and particularly against serogroup C isolates. The development of a vaccine against serogroup B strains for routine immunization is still uncertain. However, the use of specific vaccines based on antigenic formulations of class 1 protein, to be applied in epidemic situations, is closer to becoming a reality. Because of the current absence of a universal vaccine against N. meningitidis, specific surveillance programs are required to evaluate the importance of recombination processes affecting capsular expression. This type of event could produce new strain variants able to avoid the immunological response generated after vaccination.