Trends in Meningococcal Disease in the United States Military, 1971–2010

Michael P. Broderick

, Dennis J. Faix, Christian J. Hansen, and Patrick J. Blair

Author affiliations: Naval Health Research Center, San Diego, California, USA

Abstract

Meningococci have historically caused extensive illness among members of the United States military. Three successive meningococcal vaccine types were used from 1971 through 2010; overall disease incidence dropped by >90% during this period. During 2006–2010, disease incidence of 0.38 (cases per 100,000 person-years) among members of the US military was not significantly different from the incidence of 0.26 among the age-matched US general population. Of the 26 cases in the US military, 5 were fatal, 15 were vaccine failures (e.g., illness in a person who had been vaccinated), and 9 were caused by Neisseria meningitidis serogroup Y. Incidences among 17- to 19-year-old basic trainees and among US Marines were significantly higher than among comparison military populations (p<0 .05=".05" 2007.="2007." after="after" apparent="apparent" change="change" conjugate="conjugate" data="data" demonstrate="demonstrate" disease="disease" effective.="effective." epidemiology="epidemiology" in="in" is="is" meningococcal="meningococcal" no="no" observed="observed" of="of" p="p" polysaccharide="polysaccharide" quadrivalent="quadrivalent" replacement="replacement" that="that" the="the" vaccination="vaccination" vaccine="vaccine" was="was" with="with">

Cases of meningococcal disease have long plagued the United States military, with incidences (defined as cases per 100,000 person-years) as high as 150 during World War I (1) and 80 during World War II (2). Corresponding incidences among the US general population were 9 and 16 during World War I and World War II, respectively (2). In 1969, the incidence among US Army basic trainees was 81 (2). Such elevated incidences relative to the non–age-matched US population were attributed to crowding and unhygienic conditions in unique environments. In particular, these factors imposed higher incidences of disease at military basic training centers. Contributing factors likely included the convergence of people from a wide geographic area and the extreme physical demands of basic military training.

Figure 1

Thumbnail of Timeline showing 100 years of meningococcal disease incidence in the US population compared with members of the US Army (A) and effects of introduction of meningococcal vaccines (B; years in which the vaccine types were introduced into the military indicated by arrows). Rates are unadjusted for age matching. Data for the US Army and the general population for 1910–1946 from Brundage and Zollinger (2). General population data for 1967–1977 from Brundage and Zollinger (2) and for 1978

Figure 1. . . . Timeline showing 100 years of meningococcal disease incidence in the US population compared with members of the US Army (A) and effects of introduction of meningococcal vaccines (B;...

During the past century, US military incidence of meningococcal disease has markedly decreased to converge with that of the (non–age-adjusted) US general population (Figure 1). Since the 1970s, the military has maintained a policy of universal meningococcal vaccination for all persons entering all branches of service. After the US Army’s early 1970s introduction to all incoming personnel of a vaccine targeting N. meningitidis serogroup C, disease rates dropped by >90% (1,4,5). However, during 1971–1989, the Army’s mean annual incidence remained significantly higher than that among the non–age-matched general population (3.6 vs. 1.02; p<0 .0001=".0001" data="data" em="em" from="from" general="general" population="population">3
]). In 1982, a quadrivalent polysaccharide vaccine (MPSV-4; Menomune, Sanofi Pasteur, Bridgewater, NJ, USA) was introduced; this vaccine targets serogroups A, C, W-135, and Y. No broad-coverage vaccine against serogroup B exists (6). During 1982–1989, meningococcal disease incidence among members of the military was 2.1 (1); for 1990–2009, rates among both the Army and the US general population dropped significantly, with Army rates not significantly different from those observed in the general population (0.5 vs. 0.7; p = 0.19; general population data from [5]).
Despite declining incidence during the past 4 decades, the elevated susceptibility to meningococcal disease among members of the US military makes this population of interest regarding the performance of current vaccines. Of particular interest is the performance of the newer conjugate vaccine, MCV-4 (Menactra; Sanofi Pasteur, Swiftwater, PA, USA), which gradually replaced MPSV-4 in the military during 2006–2008. During 2009–2010, virtually all vaccinations were with MCV-4.
We report the epidemiology of 26 cases of meningococcal disease that occurred in members of the US military during 2006–2010. Demographics, geographic location, clinical syndrome, vaccination, and death rates are reviewed. Historical and current trends in the military are evaluated and compared with those of the US general population.