MENINGOCOCCAL INFECTIONS. FORT ORD AND CALIFORNIA.

Area of Science:

• Epidemiology
• Infectious Diseases
• Microbiology

Background:

• Outbreaks of meningococcal meningitis occurred at Fort Ord, California, between 1962 and 1964.
• The incidence of the disease was highest among basic trainees within the first eight weeks of training.

Purpose of the Study:

• To investigate the characteristics of a meningococcal meningitis outbreak at Fort Ord.
• To determine the serotype and drug resistance of isolated meningococci.
• To assess carrier rates and their correlation with disease occurrence.

Main Methods:

• Retrospective analysis of case data.
• Isolation and serotyping of Neisseria meningitidis.
• Assessment of carrier rates among military personnel and civilians.

Main Results:

• All isolated meningococci were serotype B.
• Approximately 50% of military patients had sulfadiazine-resistant strains.
• Carrier rates were high (20% in civilians, up to 90% in barracks after 8 weeks), but no correlation was found between carrier rates and case occurrence between barracks.

Conclusions:

• The high prevalence of sulfadiazine-resistant serotype B meningococci and high carrier rates among military trainees were key features of the outbreak.
• The widespread dissemination of meningococci makes pinpointing infection sources difficult.
• Military groups did not appear to pose an extraordinary hazard to the local civilian population, despite higher case numbers in military personnel.
• An increasing rate of meningococcal meningitis in California suggests a cyclical upswing in disease occurrence.