Sporadic meningococcal disease in adults: results of a 5-year population-based study.

Objective: To define the incidence, demographics, clinical features, and risk factors for sporadic meningococcal disease in adults (> or = 18 years) residing in metropolitan Atlanta.
Design: Prospective, population-based surveillance, with retrospective review of clinical and laboratory records.
Setting: Eight-county metropolitan Atlanta area.
Patients: All adult patients in whom Neisseria meningitidis was isolated from normally sterile sites (blood, cerebrospinal fluid) during the period 1 December 1988 to 30 November 1993.
Measurements: Incidence, relative risk, clinical and laboratory parameters, and serogroup of meningococcal isolates.
Results: For the 5-year period, 44 (33%) of 132 cases of meningococcal disease in Atlanta occurred in adults (annual incidence, 0.50/100,000 adults per year). Twenty-three (52%) of the 44 adults presented without rash or meningitis, the two most obvious signs of meningococcal disease. Pneumonia, sinusitis, or purulent tracheobronchitis, but without rash, were the likely sources of meningococcal bacteremia in 15 (34%) of the 44 adults. Twelve of the 15 patients with meningococcal respiratory infection were older than 50 years of age or were immunocompromised (or both), and three fourths of the 15 patients had disease caused by serogroups B, Y, and W-135. Overall, two thirds of adults older than 24 years of age with meningococcal 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). Meningococcemia 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 meningococcal disease occurred in adults. Over half of the adults presented without rash or meningitis. Pneumonia, sinusitis, and tracheobronchitis are important sources of bacteremic meningococcal disease, especially in immunocompromised patients and elderly persons.