Meningococcal disease in New York City, 1973 to 1978. Recognition of groups y and W-135 as frequent pathogens.

In the period 1973 through 1978, the New York City Department of Health serogrouped 648 isolates of Neisseria meningitidis and investigated 259 cases if meningococcal meningitis and meningococcemia. Although meningitis and septicemia were mainly due to groups B and C, groups Y and W-135 caused nearly one third of the cases. There was no difference in mortalities when disease caused by the classic groups A, B, and C was compared with disease caused by the new serogroups X, Y, Z, W-135, and Z'. Most isolates from the respiratory tract were from the new serogroups, especially Z and Z' (some from patients with pneumonia), as were most of those from the genitourinary tract, anal canal, and miscellaneous sites. Group X was infrequently seen. Although most of the isolations of these groups of N meningitidis are apparently from asymptomatic carriers, Y and W-135 do cause a substantial number of acute symptomatic infections, in particular, septicemia.