Serogroup Y meningococcal disease--Illinois, Connecticut, and selected areas, United States, 1989-1996.

Neisseria meningitidis is a leading cause of bacterial meningitis and sepsis in the United States. N. meningitidis is classified into serogroups based on the antigenic characteristics of its capsular polysaccharide. During 1989-1991 in the United States, serogroups B and C accounted for most (91%) of invasive meningococcal disease while serogroup Y caused < 5%; however, during 1992-1995, serogroup Y accounted for an increasing proportion of meningococcal disease. This report describes the epidemiology of serogroup Y meningococcal disease (SYMD) during 1991-1996 in Illinois and Connecticut, which conducted enhanced surveillance through active reviews of clinical records and in areas participating in active laboratory-based surveillance during 1989-1995. The findings indicate a substantial increase in the proportion of meningococcal disease caused by N. meningitidis serogroup Y since 1989.