SPORADIC MENINGOCOCCAL DISEASE IN ADULTS - RESULTS OF A 5-YEAR POPULATION-BASED STUDY

Objective: To define the incidence, demographics, clinical features, a nd risk factors for sporadic meningococcal disease in adults (greater than or equal to 18 years) residing in metropolitan Atlanta. Design: P rospective, population-based surveillance, with retrospective review o f clinical and laboratory records. Setting: Eight-county metropolitan Atlanta area. Patients: All adult patients in whom Neisseria meningiti dis was isolated from normally sterile sites (blood, cerebrospinal flu id) during the period 1 December 1988 to 30 November 1993. Measurement s: Incidence, relative risk, clinical and laboratory parameters, and s erogroup of meningococcal isolates. Results: For the 5-year period, 44 (33%) of 132 cases of meningococcal disease in Atlanta occurred in ad ults (annual incidence, 0.50/100 000 adults per year). Twenty-three (5 2%) of the 44 adults presented without rash or meningitis, the two mos t obvious signs of meningococcal disease. Pneumonia, sinusitis, or pur ulent tracheobronchitis, but without rash, were the likely sources of meningococcal bacteremia in 15 (34%) of the 44 adults. Twelve of the 1 5 patients with meningococcal respiratory infection were older than 50 years of age or were immunocompromised (or both), and three fourths o f the 15 patients had disease caused by serogroups B, Y, and W-135. Ov erall, two thirds of adults older than 24 years of age with meningococ cal disease had one or more immunocompromising conditions (for example , low complement 50 level [CH50], corticosteroid use, congestive heart failure, multiple myeloma, human immunodeficiency virus infection). M eningococcemia or meningococcal meningitis, often caused by serogroup C, were the presentations in 14 of 15 adults 18 to 24 years old; only 2 had an identified underlying condition. Conclusions: In this 5-year population-based study, one third of all cases of sporadic meningococc al disease occurred in adults. Over half of the adults presented witho ut rash or meningitis. Pneumonia, sinusitis, and tracheobronchitis are important sources of bacteremic meningococcal disease, especially in immunocompromised patients and elderly persons.