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Of the unexplained characteristics of the 1918-19 influenza pandemic, the extreme mortality rate among young adults (W-shaped mortality curve) is the foremost. Lack of a coherent explanation of this and other epidemiologic and clinical manifestations of the pandemic contributes to uncertainty in preparing for future pandemics. Contemporaneous records suggest that immunopathologic responses were a critical determinant of the high mortality rate among young adults and other high-risk subgroups. Historical records and findings from laboratory animal studies suggest that persons who were exposed to influenza once before 1918 (e.g., A/H3Nx 1890 pandemic strain) were likely to have dysregulated, pathologic cellular immune responses to infections with the A/H1N1 1918 pandemic strain. The immunopathologic effects transiently increased susceptibility to ultimately lethal secondary bacterial pneumonia. The extreme mortality rate associated with the 1918-19 pandemic is unlikely to recur naturally. However, T-cell-mediated immunopathologic effects should be carefully monitored in developing and using universal influenza vaccines. [ABSTRACT FROM AUTHOR]

Deaths during the 1918-19 influenza pandemic have been attributed to a hypervirulent influenza strain. Hence, preparations for the next pandemic focus almost exclusively on vaccine prevention and antiviral treatment for infections with a novel influenza strain. However, we hypothesize that infections with the pandemic strain generally caused self-limited (rarely fatal) illnesses that enabled colonizing strains of bacteria to produce highly lethal pneumonias. This sequential-infection hypothesis is consistent with characteristics of the 1918-19 pandemic, contemporaneous expert opinion, and current knowledge regarding the pathophysiologic effects of influenza viruses and their interactions with respiratory bacteria. This hypothesis suggests opportunities for prevention and treatment during the next pandemic (e.g., with bacterial vaccines and antimicrobial drugs), particularly if a pandemic strain-specific vaccine is unavailable or inaccessible to isolated, crowded, or medically underserved populations. [ABSTRACT FROM AUTHOR]

Prevention activities are designed and resourced based on perceptions of the relative population health impacts of various conditions. We examined the nature and variability of rankings of "conditions" based on how they are defined and how their population health impacts are measured. The first listed diagnosis from all hospitalizations and ambulatory visits of U.S. service members during 2002 was used to rank conditions (as defined by two standard classification systems) using five different measures of population health impacts. Less than 10% of all conditions accounted for more than one-half of total population health impact, regardless of how conditions were defined or impacts measured. However, specific conditions with the largest impacts varied depending on the classification system and impact measure. Four groups of related conditions--acute musculoskeletal injuries, pregnancy-related conditions, respiratory infections, and mental disorders (including substance abuse)--accounted for disproportionately large impacts regardless of the measure. The identification of conditions with the largest population health impacts depends on the nature and degree of aggregation in defining conditions and the measure of impact. The findings are relevant to prevention planning and resourcing. [ABSTRACT FROM AUTHOR]

Objective: To examine the risk of suicide among individuals positive for the human immunodeficiency virus (HIV) following screening for evidence of HIV infection. Prior studies have reported a 7- to 36-fold increased risk of suicide for persons with the acquired immunodeficiency syndrome.Design: Prospective cohort study.Setting: Military service applicants from throughout the United States.Main Outcome Measure: Death from suicide.Methods: The National Death Index was searched for mortality among 4147 HIV-positive military service applicants and 12437 HIV-negative applicants disqualified from military service due to other medical conditions (matched 1:3 on age, race, sex, and screening date and location) identified by the US Department of Defense between October 1985 and December 1993. Death certificates were obtained from individual states. Identifiers and HIV status of living applicants were known only by the Department of Defense.Results: The HIV-positive applicants were 92% male, 37% white, and 56% black. Median age was 24 years (range, 17-57 years). Median follow-up time was 70 months (range, 0-99 months). Ten HIV-positive (49 per 100 000 person-years) and 24 HIV-negative applicants (36 per 100 000 person-years) died of suicide (rate ratio [RR], 1.35; 95% confidence interval [CI]= 0.58-2.93). Suicide rates among both HIV-positive (RR, 2.08; 95% CI, 1.00-3.82) and HIV-negative (RR, 1.67; 95% CI, 1.07-2.48) applicants are marginally higher than those for the US general population, after adjustment for age, race, and sex. Time from screening to death was less than 3 months for 3 of 10 HIV-positive and 2 of 24 HIV-negative applicants who died of suicide.Conclusions: The HIV-positive individuals do not appear to have a significantly increased risk of death from suicide in the months following HIV screening in this study population. Because suicide risk is reported to be greatly increased after symptomatic HIV disease is present, clinicians should consider asking persons with HIV infection about suicide risk factors during both initial counseling and subsequent medical care. [ABSTRACT FROM AUTHOR]

From 23 April to 13 May 1995, an outbreak of acute respiratory disease (ARD) hospitalizations occurred in basic training soldiers at Fort Jackson, South Carolina. Weekly hospitalization rates for the most affected military unit reached 11.6%. Virus isolation and serologic studies from a sample of patients identified the agent as adenovirus type 4. Prior to starting vaccinations against adenovirus types 4 and 7 in 1971, these serotypes were the major causes of ARD in basic trainees. No outbreaks were reported when the vaccines were used. A logistical error temporarily interrupted vaccine production, and newly arriving trainees received no adenovirus vaccines from the summer of 1994 through late March 1995. This outbreak occurred in unvaccinated soldiers. The sole manufacturer has permanently stopped adenovirus vaccine production. All type 4 vaccine supplies are now depleted. This outbreak demonstrates continued susceptibility of military recruits to adenovirus type 4 and warns of future outbreaks. Copyright © 1999 The University of Chicago [ABSTRACT FROM AUTHOR]

Military training exercises are conducted routinely in the Mojave Desert. To determine whether assignment in this desert environment increases risk of respiratory illnesses, hospitalization rates were compared between two matched cohorts of soldiers during three intervals of follow-up during a 10-year surveillance period. The exposed cohort (N = 21,543) included all soldiers who were ever assigned to the Mojave Desert during the surveillance period. The control cohort (N = 86,172) included soldiers matched on demographic characteristics who were never assigned to the Mojave Desert during the surveillance period. Three follow-up intervals ("before," "during," "after") were defined relative to times when exposed soldiers were assigned to the desert. Rates of respiratory hospitalizations were similar between the cohorts for the "before" and "during" intervals but were higher in the exposed cohort for the "after" interval (rate ratio, 1.30; 95% confidence interval, 1.07-1.59). This difference was largely attributable to excess pneumonia and influenza hospitalizations in the exposed cohort. Healthy, young adults may have increased susceptibility to respiratory infectious illnesses after prolonged exposures to desert environments. [ABSTRACT FROM AUTHOR]

Background: In the United States, the leading cause of death for young men is unintentional injury. The experience of the U.S. Army, because it comprises mostly young men, provides insights into factors associated with risk of accidental death. Between 1990 and 1998, accidents accounted for more than half of all deaths of men on active duty in the U.S. Army.Methods: All men on active duty in the U.S. Army who died in an accident between 1990 and 1998 were included in the study. For each accidental death case, four randomly selected controls were also included, matched on gender and contemporaneous military service.Results: In multivariate analyses, accidental death victims were more likely to be unmarried, limited to a high school education, in combat-specific occupations, veterans of a recent deployment, and previously hospitalized for an "injury/poisoning," "mental disorder," or "sign/symptom/ill-defined condition." Of behaviors reported on routine health risk assessments, the strongest predictor of a subsequent fatal accident was motorcycle use while the most excess deaths were attributable to consuming more than five alcoholic drinks per week.Conclusions: There are characteristics, experiences, and behaviors that predict accidental death risk. The findings may inform safety and health promotion programs aimed at young adults. [ABSTRACT FROM AUTHOR]

In 1918, two waves of epidemic influenza arose with very different clinical phenotypes. During the first wave, infection rates were high but mortality was low. During the second wave, high numbers of deaths occurred and mortality differed 30-100 times among seemingly similar groups of affected adults, but the reason for this variation is unclear. In 1918, the crews of most warships and some island populations were affected by influenza during both waves of infection and had no or very few deaths during the second wave. However, some warships and island populations were not affected during the first wave of infection and had high mortality during the second wave. These findings suggest that infection during the first wave protected against death, but not infection, during the second wave. If so, the two waves of infection were probably caused by antigenically distinct influenza viruses--not by one virus that suddenly increased in pathogenicity between the first and second waves. These findings are relevant to modern concerns that the 2009 influenza A H1N1 virus could suddenly increase in lethality. [ABSTRACT FROM AUTHOR]

The 1918-21 influenza pandemic was the most lethal natural event in recent history. In the Pacific region, the pandemic's effects varied greatly across different populations and settings. In this region, the pandemic's lethal effects extended over 3 years, from November, 1918, in New Zealand to as late as July, 1921, in New Caledonia. Although a single virus strain probably affected all the islands, mortality varied from less than 0·1% in Tasmania, to 22% in Western Samoa. The varied expressions of the pandemic across the islands reflected the nature and timing of past influenza epidemics, degrees of social isolation, ethnicity and sex-related effects, and the likelihood of exposures to pathogenic respiratory bacteria during influenza illnesses. The high case-fatality rate associated with this pandemic seems unlikely to recur in future influenza pandemics; however, understanding the critical determinants of the mass mortality associated with the 1918-21 pandemic is essential to prepare for future pandemics., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

During the 15-year surveillance period, there were 2,233 incident diagnoses of malignant melanoma among members of the active component of the U.S. military (unadjusted incidence rate 1.08 cases per 10,000 person-years [p-yrs]). Unadjusted incidence rates were highest in the fi xed-wing pilot/ crew group (2.45 per 10,000 p-yrs); lowest in the infantry, special operations, combat engineer group (0.77 per 10,000 p-yrs); and intermediate among healthcare providers (1.33 per 10,000 p-yrs) and all others (1.07 per 10,000 p-yrs). During the 15-year period, rates of malignant melanoma diagnoses among U.S. military members overall increased in an exponential fashion in relation to years of active service. However, this relationship varied across occupational groups. Most notably, after several years of service, rates of melanoma diagnoses increased relatively rapidly among pilots and the crews of fixed-wing aircraft (e.g., fighters, bombers, cargo/personnel transporters) and those in occupations inherently conducted outdoors (e.g., infantry, special operations, combat engineers). In contrast, melanoma diagnosis rates increased relatively slowly among healthcare providers and those in "other" military occupations. The findings reiterate the importance of limiting, to the extent possible given mission requirements, exposures of military members to solar ultraviolet and cosmic ionizing radiation.

During the 1918-1919 pandemic, influenza mortality widely varied across populations and locations. Records of U.S. military members in mobilization camps (n = 40), military academies, and officer training schools were examined to document differences in influenza experiences during the fall 1918. During the fall-winter 1918-1919, mortality percentages were higher among soldiers in U.S. Army mobilization camps (0.34-4.3%) than among officer trainees (0-1.0%). Susceptibility to infection and clinical expressions of 1918 pandemic influenza varied largely based on host epidemiological characteristics rather than the inherent virulence of the virus., (Reprint & Copyright © 2016 Association of Military Surgeons of the U.S.)

The reasons for the unprecedented mortality during the 1918 influenza pandemic remain poorly understood. We examined morbidity records from three military cohorts from years prior to and during the 1918 pandemic period to assess the effects of previous respiratory illnesses on experiences during the pandemic. Clinical registers and morbidity lists were examined to identify all medical encounters for acute respiratory illnesses in students at two U.S. military officer training academies and Australian soldiers deployed in Europe. Influenza-like illness prior to the major pandemic wave of 1918 predisposed Australian soldiers [relative risk (RR) 1·37, 95% confidence interval (CI) 1·18-1·60, P < 0·0001] and US officer trainees at West Point (RR 3·10, 95% CI 2·13-4·52, P < 0·0001) and Annapolis (RR 2·03, 95% CI 1·65-2·50, P < 0·0001) to increased risks of medically treated illnesses in late 1918. The findings suggest that susceptibility to and/or clinical expressions of the 1918 pandemic influenza virus depended on previous experiences with respiratory infectious agents. The findings are consistent with observations during the 2009 pandemic in Canada and may reflect antibody-dependent enhancement of influenza infection.

Urinary stones can cause debilitating morbidity that impairs the operational effectiveness of affected members of the U.S. Armed Forces. This report documents that, during the past 5 years, rates of incident diagnoses of urinary stones decreased by about 17% in the active component of the U.S. military. During the period, annual rates of inpatient diagnosed cases were low and relatively stable, while rates of outpatient diagnosed cases slightly decreased. Incidence rates were slightly higher among females than males in 2011; however, rates were very similar among males and females from 2012 through 2015. Rates of incident diagnoses among white, non-Hispanic and Native American/Alaska Native service members were consistently 80%-100% higher than among black, non-Hispanic and Asian/Pacific Islander service members and 35%-45% higher than among Hispanic and "other race/ethnicity" service members. During the 5-year period, a total of 3,350 service members received more than one incident diagnosis of urinary stones ("recurrent cases"); one-tenth (10.2%) of all incident cases during the period were recurrent cases. Service members with histories of urinary stones should be counseled and closely supervised to avoid dehydration and to adhere to diets that reduce the risk of stone formation.

This report summarizes frequencies and timing of first and recurrent episodes of back pain treated in the U.S. Military Health System among more than 2 million military members who began active service between July 2000 and June 2012. In the population overall, at least 5% were affected by clinically significant back pain within 6 months and 10% within 13 months of beginning active service; and 34% had at least one episode of back pain while in active service during the surveillance period. After initial episodes of back pain, more than half (54%) of those affected had at least one recurrent episode; and after first recurrences, 65% had second recurrences while still in active service. In general, back pain episode-free periods preceding initial and between successive episodes markedly decreased during the period. Frequencies and timing of back pain episodes varied in relation to service branch, gender, and occupation. Acute back pain is a common disorder that is unpredictable in onset and often debilitating. Its prevention should be a military medical research objective of high priority.

Throughout history, acute respiratory illnesses (ARIs) have disproportionately affected military populations, particularly those in recruit training camps. A similar dynamic can affect non-trainee military settings. When military members are reassigned, they often develop ARIs within the first weeks of their arrivals at their new assignments. To assess the natures and magnitudes of the risks associated with new assignments, this analysis compared the experiences of service members within their first full calendar months at new assignments and during the same months at the same locations 1 year later. The results do not support the hypothesis that ARIs of infectious etiologies consistently occur more frequently soon after arriving at new assignments compared to 1 year later at the same locations. In contrast, during two-thirds of the 117 months considered here, rates of ARIs of presumed allergic etiologies (e.g., allergic rhinitis, asthma) were higher during the first months of new assignments compared to 1 year later. The limitations of the study methodology as well as the possible implications of the findings are discussed.

This report describes the trends in length of military service for active component members of the U.S. Armed Forces who were diagnosed with human immunodeficiency virus type 1 (HIV-1) infections during 1990-2013. Durations of service after service members' initial diagnoses of HIV-1 infection were compared for five different cohorts that corresponded to when diagnoses were made during the 5-year intervals beginning in 1990, 1995, 2000, and 2005, and the 4-year interval of 2010-2013. By several measures, the durations of service after initial diagnoses of HIV-1 infection increased from the earliest to the later cohorts. The findings are discussed in the context of changes in several factors during the surveillance period: the growing availability and effectiveness of treatments for HIV-1 disease; the stigmas associated with the diagnosis of HIV-1 infection and its link to homosexuality; and the changes in U.S. military policy about the inclusion of homosexuals in its ranks. Also discussed are the limitations of the estimates for the most recent cohorts and the future prospects for continued lengthening of service for those infected with HIV-1.

Traumatic brain injury (TBI) and post-traumatic stress disorder (PTSD) are "signature wounds" of the Afghanistan/Iraq wars; however, many TBI/PTSD cases are not war related. During the wars, diagnoses of TBI/PTSD among military members increased because risks of TBI/PTSD, and capabilities to detect cases, increased. This report summarizes TBI/PTSD diagnosis experiences of three cohorts of overseas deployers in relation to the natures of their exposures to active war service and enhanced case ascertainment efforts. The findings suggest that, during the war, the proportions of PTSD diagnoses attributable to war zone service decreased from approximately 80% to less than 50%, while the proportions attributable to enhanced case ascertainment increased from less than 10% to nearly 50%. The proportions of TBI diagnoses attributable to war zone service more than tripled from 2003-2005 (13.1%) through 2007-2009 (44.8%); the proportions attributable to enhanced ascertainment also markedly increased, but not until after 2007. By the end of the war, war zone service and enhanced ascertainment accounted for similar proportions of all PTSD and TBI diagnoses. If programs and resources currently focused on TBI and PTSD continue, rates of diagnoses post-war will greatly exceed those pre-war.

Until the mid-20th century, mortality rates were often very high during measles epidemics, particularly among previously isolated populations (e.g., islanders), refugees/internees who were forcibly crowded into camps, and military recruits. Searching for insights regarding measles mortality rates, we reviewed historical records of measles epidemics on the Polynesian island of Rotuma (in 1911), in Boer War concentration camps (in 1900-1902), and in US Army mobilization camps during the First World War (in 1917-1918). Records classified measles deaths by date and clinical causes; by demographic characteristics, family relationships (for Rotuma islanders and Boer camp internees), and prior residences; and by camp (for Boer internees and US Army recruits). During the Rotuman and Boer War epidemics, measles-related mortality rates were high (up to 40%); however, mortality rates differed more than 10-fold across camps/districts, even though conditions were similar. During measles epidemics, most deaths among camp internees/military recruits were due to secondary bacterial pneumonias; in contrast, most deaths among Rotuman islanders were due to gastrointestinal complications. The clinical expressions, courses, and outcomes of measles during first-contact epidemics differ from those during camp epidemics. The degree of isolation from respiratory pathogens other than measles may significantly determine measles-related mortality risk.

Very few Pacific islands escaped the 1918-1919 influenza pandemic. Subsequent influenza epidemics in the established colonial outposts of American Samoa and New Caledonia infected many but killed very few persons whereas the extraordinarily isolated Niue, Rotuma, Jaliut and Yule islands experienced high mortality influenza epidemics (>3% of population) following 1918. These dichotomous outcomes indicate that previous influenza exposure and degree of epidemiological isolation were important mortality risk factors during influenza epidemics on Pacific islands.

Background: During the 1918 pandemic period, influenza-related mortality increased worldwide; however, mortality rates varied widely across locations and demographic subgroups. Islands are isolated epidemiological situations that may elucidate why influenza pandemic mortality rates were so variable in apparently similar populations., Objectives: Our objectives were to determine and compare the patterns of pandemic influenza mortality on islands., Methods: We reviewed historical records of mortality associated with the 1918-1920 influenza pandemic in various military and civilian groups on islands., Results and Conclusions: Mortality differed more than 50-fold during pandemic-related epidemics on Pacific islands [range: 0.4% (Hawaii) to 22% (Samoa)], and on some islands, mortality sharply varied among demographic subgroups of island residents such as Saipan: Chamorros [12%] and Caroline Islanders [0.4%]. Among soldiers from island populations who had completed initial military training, influenza-related mortality rates were generally low, for example, Puerto Rico (0.7%) and French Polynesia (0.13%). The findings suggest that among island residents, those who had been exposed to multiple, antigenically diverse respiratory pathogens prior to infection with the 1918 pandemic strain (e.g., less isolated) experienced lower mortality. The continuous circulation of antigenically diverse influenza viruses and other respiratory infectious agents makes widespread high mortality during future influenza pandemics unlikely., (© 2012 Blackwell Publishing Ltd.)

Purulent bronchitis was a distinctive and apparently new lethal respiratory infection in British and American soldiers during the First World War. Mortality records suggest that purulent bronchitis caused localized outbreaks in the midst of a broad epidemic wave of lethal respiratory illness in 1916-1917. Probable purulent bronchitis deaths in the Australian Army showed an epidemic wave that moved from France to England. Purulent bronchitis may have been the clinical expression of infection with a novel influenza virus which also could have been a direct precursor of the 1918 pandemic strain., (© 2011 Blackwell Publishing Ltd.)

Since 2002, approximately 40,000 US civilians and 2.1 million military personnel have been vaccinated against smallpox. The vaccine contains live vaccinia virus that can be transferred through physical contact. This report summarizes numbers, rates, and characteristics of contact vaccinia cases that presented between December 2002 and March 2011. Cases were identified from reports in adverse event reporting systems and peer-reviewed literature. One hundred fifteen cases of vaccinia transmission through contact were identified (5.4 per 100,000 vaccinees); 52 reports (45%) noted laboratory confirmation. Three-quarters of vaccinees, but fewer than 8% of contact vaccinia cases, were described as military members. Most cases were household or intimate contacts (n=86, 75%) or wrestling partners (n=18, 16%) of vaccinees. Nearly all cases manifested mild, local skin reactions; of 14 hospitalized cases, one was life-threatening. Vaccinia transmission from vaccinees is relatively infrequent. Continued attention to both vaccinee education and screening for contraindications to vaccination is appropriate., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

To estimate malaria rates in association with birth country, we analyzed routine surveillance data for US military members. During 2002-2010, rates were 44× higher for those born in western Africa than for those born in the United States. Loss of natural immunity renders persons susceptible when visiting birth countries. Pretravel chemoprophylaxis should be emphasized.

Rotuma is an isolated Polynesian island. In January 1911, most residents of Rotuma (population approximately 2,600) were exposed to measles virus for the first time. The official mortality register documented 491 deaths due to all causes among Rotumans during 1911 (cumulative measles-related mortality: 12.8%); most deaths occurred in April-May and were attributed to measles and its sequelae. Measles-related mortality rates were higher among young children (23.4 per 100 person-years) and young adults (17.1 per 100 person-years) than among adolescents (11.0 per 100 person-years) and older adults (5.6 per 100 person-years); females (16.2 per 100 person-years) died at a higher rate than males (13.2 per 100 person-years). Gastrointestinal complications (75%), not respiratory complications, were the predominant clinical manifestations of fatal measles cases; tuberculosis mortality was unusually high during the year of the epidemic. In 1911, measles-related mortality varied by nearly 3-fold across geographic districts (range, 7.4%-21.6%). The extreme mortality due to measles on Rotuma typifies the experiences of isolated populations after first encounters with measles; it suggests that prior exposures to a narrow range of microbes and genetic homogeneity predispose isolated populations to lethal outcomes when they are first exposed to highly contagious and pathogenic viruses (e.g., measles, influenza).

Background: During the 1918-1919 influenza pandemic, nurses and physicians were intensively exposed to the pandemic A/H1N1 strain. There are few published summaries of the mortality experiences of nurses and physicians during the pandemic., Methods: Mortality records from U.S. and British Armies during the First World War and obituary notices in national medical association journals were reviewed to ascertain death notices of nurses and physicians likely to have died of influenza., Results: Illness-related mortality among U.S. military nurses (1·05%) was one and one-half times higher than among U.S. medical officers (0·68%), nearly two times higher than among British medical officers (0·55%), and nine times higher than among British nurses (0·12%). Among U.S. nursing officers, mortality was approximately twice as high among those assigned in the United States than in Europe. Among civilian physicians, mortality during the influenza pandemic was markedly increased in Canada, New Zealand, South Africa and the United States but not Australia., Conclusions: During the 1918 pandemic, mortality among nurses and physicians was relatively low compared to their patients and significantly varied across locations and settings. Medical-care providers (particularly U.S. nursing officers) who were new to their assignments when pandemic-related epidemics occurred may have had higher risk of influenza-related mortality because of occupational exposures to bacterial respiratory pathogens that they had not previously encountered., (© 2011 Blackwell Publishing Ltd.)

Background: Understanding the risk of mortality during the 1918-1919 influenza pandemic could inform preparations for a future pandemic., Methods: Prospectively collected demographic, hospitalization, and death data from all individuals who served in the Australian Imperial Force from 1914 through 1919 in Europe and the Middle East were abstracted from archived records. Analyses were conducted to determine mortality risk factors., Results: Hospitalization with a respiratory illness during the spring-summer of 1918 protected soldiers from death (odds ratio, 0.37 [95% confidence interval, 0.25-0.53]; P < .001) but not from hospitalization during the fall-winter of 1918-1919. During the fall-winter of 1918-1919, there was a strong inverse relationship between risk of dying of pneumonia-influenza and time in military service. The pneumonia-influenza death rate among men who enlisted in 1918 (6.33 deaths per 100 person-years) was 9 times higher than that among the 1917 enlistment cohort (0.72 deaths per 100 person-years) and >14 times higher than that among the 1916 cohort (0.43 deaths per 100 person-years), 1915 cohort (0.29 deaths per 100 person-years), and 1914 cohort (0.28 deaths per 100 person-years)., Conclusion: There was a strong inverse relationship between length of service in the Australian Imperial Force and mortality risk from pneumonia-influenza during the fall-winter of 1918-1919. The protective effect of increased service likely reflected increased acquired immunity to influenza viruses and endemic bacterial strains that caused secondary pneumonia and most of the deaths during the 1918-1919 influenza pandemic.

To assess the association between influenza immunization and subsequent diagnosis of group A streptococcus (GAS)-illness in Army recruits during influenza seasons 2002-2006. A case-control study was employed with cases as trainees with outpatient GAS diagnosis (ICD-9-CM codes: 034.0, 035, 038.0, 041.01, 320.2, 390-392, 482.31) during the influenza season, and controls as trainees with no outpatient GAS diagnosis during the influenza season. Primary exposure was influenza immunization during 1st September to 30th April of each season. Estimated protective effects of influenza immunization against GAS-illness ranged from 50% to 77%. A strong protective effect was suggested for Army trainee influenza immunization on the diagnosis of GAS-illness.

Although smallpox vaccine-associated myopericarditis has been reported, the risk of cardiac ischemic events remains uncertain. We identified personnel receiving the smallpox vaccination and compared them to a historical referent population. The rate of cardiac ischemia diagnoses in the 30 days following smallpox vaccination was 140.1 per 100,000 person-years, compared to 143.5 per 100,000 person-years in referent group (RR 1.0 [95% CI: 0.7-1.4]). The rate of cardiac ischemic events in vaccinees was 121.4 per 100,000 person-years before and 175.7 after adopting pre-vaccination cardiac screening (RR 1.4 [95% CI: 0.8-2.7]). Implementation of pre-vaccination cardiac risk factor screening was not associated with a reduction in cardiac events.

Objective: To assess how numbers and age distributions of cases and deaths during an influenza pandemic in the United States would potentially vary from those during the 1918-1919 pandemic, given the same virulence of the pandemic strain., Methods: Influenza cases and deaths in two referent populations (U.S. residents in 1917 and 2006) were calculated using clinical case rates from three pandemics (1918-like, 1957-like, and 1968-like) and case fatality rates from the 1918-1919 pandemic., Results: Across pandemic scenarios, overall case ("attack") rates ranged from 24.7% to 34.2%, and overall death rates ranged from 4.4 to 6.7 per 1000. In both referent populations, total cases and deaths were significantly higher when using 1957-like and 1968-like, compared to 1918-like, case rates. Under all pandemic scenarios, the most deaths occurred among those aged 25 to 29 years. However, in the 2006 referent population, there were large numbers and high proportions of deaths in middle-aged and elderly adults (unlike during the 1918-1919 pandemic)., Conclusions: Numbers and distributions of cases and deaths during influenza pandemics depend on numbers of individuals, clinical case rates, and case fatality rates in relation to age. During a future pandemic in the United States, influenza deaths will likely not be as sharply focused in young adults as in 1918-1919 (even if case fatality rates are similar) because of larger proportions of middle-aged and elderly adults and potentially higher case rates among adults older than 30.

It is commonly believed that the clinical and epidemiological characteristics of the next influenza pandemic will mimic those of the 1918 pandemic. Determinative beliefs regarding the 1918 pandemic include that infections were expressed as primary viral pneumonias and/or acute respiratory distress syndrome, that pandemic-related deaths were the end states of the natural progression of disease caused by the pandemic strain, and that bacterial superinfections caused relatively fewer deaths in 1918 than in subsequent pandemics. In turn, response plans are focused on developing and/or increasing inventories of a strain-specific vaccine, antivirals, intensive care beds, mechanical ventilators, and so on. Yet, there is strong and consistent evidence of epidemiologically and clinically important interactions between influenza and secondary bacterial respiratory pathogens, including during the 1918 pandemic. Countermeasures (eg, vaccination against pneumococcal and meningococcal disease before a pandemic; mass uses of antibiotic(s) with broad spectrums of activity against common bacterial respiratory pathogens during local epidemics) designed to prevent or mitigate the effects of influenza-bacterial interactions should be major focuses of pandemic-related research, prevention, and response planning.

Routine vaccinations of US military personnel with Anthrax Vaccine Adsorbed began in 1998. To systematically identify clinical diagnoses reported more frequently after vaccination than before, all military personnel were retrospectively assigned to pre- or post-vaccination cohorts. Cohort assignments were based on vaccination statuses each day of the 3-year surveillance period. For each cohort, rates of hospitalizations and ambulatory visits for 843 specific diagnoses were calculated using data in a public health surveillance system. Compared to the pre-vaccination cohort, the post-vaccination cohort had statistically higher rates of hospitalizations for 17 diagnoses, of ambulatory visits for 34 diagnoses, and in both clinical settings for one diagnosis (malaria). After accounting for systematic differences in coding/reporting and residual confounding, the number and nature of clinical diagnoses more frequent after anthrax vaccination than before were consistent with expectations due to random variation. This surveillance suggests that Anthrax Vaccine Adsorbed has few, if any, clinically significant adverse effects.

Since 1985, the U.S. Armed Forces have conducted routine testing of personnel for antibodies to human immunodeficiency virus type 1. Sera that remain after testing are archived in the Department of Defense serum repository for potential uses in medical surveillance, clinical, and research activities. The goal of this study was to document the timing and completeness of routine human immunodeficiency virus type 1 testing among active duty military personnel and to identify factors associated with more recent testing. Demographic characteristics for active duty personnel were obtained from the Defense Medical Surveillance System. Of all individuals on active duty on August 31, 2001 (N = 1,370,367), 98.6% had been tested. Older personnel, those with postgraduate degrees, and married personnel had the longest time intervals since their most recent tests. The results of this analysis may inform the planning and conduct of human immunodeficiency virus type 1 prevention programs as well as deployment-related or other surveillance activities.

The Defense Medical Surveillance System (DMSS) is the central repository of medical surveillance data for the US armed forces. The DMSS integrates data from sources worldwide in a continuously expanding relational database that documents the military and medical experiences of service members throughout their careers. The Department of Defense Serum Repository (DoDSR) is a central archive of sera drawn from service members for medical surveillance purposes. Currently, the DMSS contains data relevant to more than 7 million individuals who have served in the armed forces since 1990, and the DoDSR contains more than 27 million specimens that are linkable to data in the DMSS. Recent applications of the DMSS and DoDSR provide glimpses of the capabilities and uses of comprehensive public health surveillance systems.

Historically, military recruits have been at high risk of acquiring meningococcal disease. Beginning in the 1940s, the US military relied on mass treatment with sulfadiazine to control outbreaks in training camps. In the 1960s, a vaccine was developed in response to the emergence of sulfadiazine-resistant strains. Since 1971, all new recruits in the US military have been immunized against Neisseria meningitidis during their first days of service. Serogroups represented in vaccines given to service members have changed over time: the quadrivalent (A, C, Y, W135) vaccine has been given since 1982. In the US military, meningococcal disease rates decreased by approximately 94% from 1964 to 1998. After initiating routine immunization in 1971, crude rates decreased sharply and have remained low; in addition, there have been few cases of disease caused by serogroups represented in contemporaneously administered vaccines. In the US military, immunizations have been effective for the prevention of disease caused by vaccine-homologous serogroups of N. meningitidis.

Objective: Epidemiological studies have shown that mental disorders are associated with reduced health-related quality of life, high levels of health care utilization, and work absenteeism. However, measurement of the burden of mental disorders by using population-based methods in large working populations, such as the U.S. military, has been limited., Method: Analysis of hospitalizations among all active-duty military personnel (16.4 million person-years) from 1990 to 1999 and ambulatory visits from 1996 to 1999 was conducted by using the Defense Medical Surveillance System. Rates of hospitalization, ambulatory visits, and attrition from military service were compared for persons with mental disorder diagnoses and those with diagnoses in 15 other ICD-9 disease categories., Results: Mental disorders was the leading category of discharge diagnoses among men and the second leading category among women; 13% of all hospitalizations and 23% of all inpatient bed days were attributed to mental disorders. Six percent of the military population received ambulatory services for mental disorders annually in 1998 and 1999. Among a 1-year cohort of personnel, 47% of those hospitalized for the first time for a mental disorder left military service within 6 months. This attrition rate was significantly different from the rate of only 12% after hospitalization for any of the 15 other disease categories (range=11%-18%) (relative risk=4.04, 95% confidence interval=3.91-4.17). The difference remained significant after controlling for effects of age, gender, and duration of service., Conclusions: Mental disorders appear to represent the most important source of medical and occupational morbidity among active-duty U.S. military personnel. These findings provide new population-based evidence that mental disorders are common, disabling, and costly to society.

Bell's palsy is a relatively common disease characterized by the sudden onset of unilateral facial paralysis. Using a centralized surveillance system that contains demographic, military assignment, and medical encounter data of US military service members, the authors estimated rates, trends, and demographic correlates of risk of Bell's palsy during a 2-year period. Poisson regression was used to estimate the independent effects of climate, season, and latitude. From October 1997 to September 1999, there were 1,181 incident cases of Bell's palsy among US service members. The crude incidence rate was 42.77 per 100,000 person-years. Incidence rates increased with age and were higher among females, Blacks, Hispanics, married persons, and enlisted service members. Both climate (adjusted rate ratio for arid vs. nonarid climate = 1.34) and season (adjusted rate ratio for cold vs. warm months = 1.31) were independent predictors of risk of Bell's palsy. Latitude was not a statistically significant predictor when demographic, climate, and season effects were taken into account. The results are consistent with hypotheses regarding viral etiologies (e.g., reactivation of herpes simplex) of Bell's palsy.

Background: There are relationships among morbidity experiences before, during, and after participation in overseas military operations., Methods: U.S. servicemembers who deployed to Bosnia-Herzegovina during a 4-year period were classified based on their last hospitalizations prior to deploying. Hospitalization rates during and following deployment were calculated in relation to the timing and causes of pre-deployment hospitalizations., Results: Deployers ever hospitalized pre-deployment were 120% and 50% more likely to be hospitalized during and following deployment, respectively. For nearly every category of diagnoses, hospitalization rates during and following deployment were highest among those hospitalized for the same category, intermediate among those hospitalized for other categories, and lowest among those not hospitalized prior to deploying. Deployers hospitalized within 1 month, 2-3 months, or > 3 months of deploying were 3.8, 2.6, and 1.4-times more likely to be hospitalized during deployment., Conclusions: The nature and recency of prior hospitalizations significantly determine during and post-deployment hospitalization risks.

Objectives: To assess incidence rates of eye injuries in the US Armed Forces and to identify demographic and occupational correlates of risk., Design: Retrospective population-based study., Setting: US military medical facilities worldwide., Participants: All individuals in the US Armed Forces during 1998., Main Outcome Measures: Incidence rates of hospitalizations and ambulatory visits for eye injuries., Results: The incidence rate of ambulatory visits (983 per 100 000 person-years) for eye injuries was 58 times higher than the incidence rate of hospitalizations (17 per 100 000 person-years) for eye injuries. Orbital floor fractures, contusions, and open wounds to the ocular adnexa and orbit accounted for 85% of eye injuries resulting in hospitalization, while 80% of ambulatory visits were for superficial wounds and foreign bodies. Hospitalization rates varied widely across demographic subgroups. Men had twice the incidence rate as women, and the youngest age group (17-24 years) had 6 times the incidence rate of the oldest age group (35-65 years). Together, motor vehicle crashes and fights caused nearly half of the hospitalizations. Ambulatory rates varied significantly in relation to occupation but not to demography. Tradespeople (eg, metal body machinist, welder, and metalworker) had incidence rates 3 to 4 times higher than the overall population rate., Conclusions: Hospitalization and ambulatory data provide different views of the morbidity associated with eye injuries. General safety precautions and behavior modification, rather than eye-specific interventions, are indicated to prevent the most serious eye injuries. However, the consistent use of eye protection during known hazardous occupational activities could prevent much of the morbidity associated with the less serious, yet more common, eye injuries.

Background/objectives: Few studies of Chlamydia trachomatis incidence, especially among men, and most studies of C. trachomatis in US military populations are cross sectional prevalence surveys. A population based retrospective cohort was used to determine risk factors for repeat diagnoses of genital C. trachomatis infections among male and female soldiers with previous C. trachomatis infections., Methods: All active duty soldiers diagnosed with C. trachomatis genital infections between 1994 and 1998. Cohort members were passively followed until repeat diagnoses of C. trachomatis infection, termination of army service, or the end of the study., Results: Among 11,771 soldiers with initial diagnoses of chlamydia, the crude rate of repeat diagnoses was 52.0 per 1000 person years. Women and men aged 20-24 were at greatest unadjusted risk of reinfection. After adjustment, women aged 20-24 and men aged 25-29 were at higher risk than their younger or older counterparts., Conclusions: Results of this study suggest that both male and female soldiers who are diagnosed with chlamydia infections have relatively high risks of reinfection through their 20s.