Suspected Meningococcal Meningitis on an Aircraft Carrier

Military Medicine, Sep 2004 by Farr, R Wesley, Gonzalez, Michele J, Garbauskas, Heather, Zinderman, Craig E, LaMar, James E II

Discussion

Meningococcal meningitis occurs among 0.6 people per 100,000 population per year in the United States and is the leading cause of bacterial meningitis in the 2- to 18-year age group.1 The mortality rate for meningococcal meningitis is 3% but increases to 17% if bacteremia is present.1 People at higher risk for developing meningococcal meningitis include people with immunodeficiency states, such as complement deficiency, asplenia, and human immunodeficiency virus infection, and people living in close crowded conditions, such as military recruits, college students in dormitories, and people of low socioeconomic status.2'3 Meningococcal meningitis is uncommon but not unprecedented in the shipboard environment. During the 10-year period from 1990 to 1999, 18 cases among active duty sailors were reported, with an annual range of O to 4 cases.4 Bohnker5 reported that a suspected case of meningococcal meningitis was one of the 10 most clinically challenging cases treated in the carrier's hospital ward.

N. meningitidis bacteria are carried in the human nasopharynx, and transmission occurs through aerosol or secretions. Asymptomatic carriage occurs in approximately 10% of the general population, but rates may be as high as 40 to 80% in military populations.6'7 Cigarette smoking and other conditions that impair the ability of the mucociliary barrier to prevent systemic invasion of microorganisms are thought to increase the risk of infection.8 The patient described was at increased risk because of the close living quarters on the ship and a coexistent upper respiratory infection. Although he had received the meningococcal vaccine 3 years before presentation, this would not have prevented disease attributable to N. meningiiidis serotype B infection or other pathogens.9

A definitive diagnosis of meningococcal meningitis was not obtained in this case. The epidemiological features, petechial rash, profound CSF pleocytosis, and rapid response to antibiotics make bacterial meningitis secondary to meningococcus the most likely cause. Barriers to diagnosis included the administration of one dose of antibiotics before lumbar puncture and the limited laboratory capabilities onboard the ship. However, the potentially devastating consequences associated with bacterial meningitis necessitate quick aggressive treatment, which was initiated before lumbar puncture was performed. The ship's medical officers relied on clinical acumen and judgment to manage the case effectively. Broad empiric antibiotic coverage was initially chosen, and treatment was then tailored to the patient's clinical response. Shipboard practitioners, without the luxury of sophisticated laboratory technology at their disposal, must often use their clinical skills alone to treat patients such as this.

Prompt initiation of recommended public health measures by the ship's medical department led to successful containment of the spread of disease. Respiratory droplet isolation was implemented immediately once the diagnosis of bacterial meningitis was entertained. Isolation was continued for the first 24 hours of antibiotic therapy, consistent with current recommendations by the American Public Health Association.10 The ship's medical department also identified the patient's close contacts and initiated prophylactic therapy for those contacts.