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2 Risks to Deployed Forces War by its nature is a tremendously hazardous endeavor. Clearly, it entails risks to life and limb from weapons and battle. At least up through World War I, however, non-battle-related disease and injury have taken an even greater toll upon the health of deployed forces than have battle injuries (Garf~eld and Neugut, 1997~. The non-combat-related risks to deployed forces include an array of differ- ent threats to health. Infectious diseases, non-battle-related injuries, injuries from heat and cold exposures, and psychological stress have been large con- tributors to casualties in war after war. Chemical and biological weapons are increasingly seen as threats to deployed forces, as are environmental contami- nants and toxic industrial chemicals. The military has responded to these threats with military medical research programs and the subsequent implementation of doctrine and protective meas- ures that have reduced the impacts of disease and non-battle injury (DNBI) to the very low levels observed in Operations Desert Shield and Desert Storm (the Gulf War) and in Bosnia. Many infectious disease threats have largely been eliminated by use of vaccines, prophylactic drugs, vector control, insect repel- lents, and protected food and water supplies. Improved clothing, footwear, and military doctrine have greatly reduced the impacts of injuries from heat and cold exposures. The strategies now in place for countering the traditional acute dis- eases and injury threats to military operations are fundamentally sound. This report has addressed these traditional concerns of military medicine in a very limited fashion and focused on improved medical surveillance to better assess and respond to traditional and emerging threats, record keeping to permit appro- priate care and retrospective analysis, and the complex issue of medically unex- plained symptoms in returning service members. 21

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22 STRATEGIESTOPROTECTTHEHEALTHOFDEPLOYED U.S. FORCES INFECTIOUS DISEASES Throughout history infectious diseases have been the single greatest threat to the health of those involved in military operations. Epidemics of contagious dis- eases such as influenza, food- and waterborne illnesses such as hepatitis, typhoid fever, and shigellosis, and vector-borne diseases such as typhus, yellow fever, malaria, and dengue have caused entire armies to become militarily ineffective (Zinsser, 1935~. Tropical and subtropical regions have been especially hazardous because of vector-borne diseases. As recently as the Vietnam War, infectious dis- eases took a heavy toll on the U.S. military population. Disease was listed as the cause of 56 to 74 percent of active-duty Army patient admissions to hospitals in Vietnam from 1965 to 1970 (Ognibene, 1982~. Until 1967, the total number of lost days of duty by active-duty Army personnel initially admitted for medical care from DNBI outfaced those from battle injury. From 1968 to 1970, DNBI contrib- uted nearly half ofthe lost days of duty (Ognibene, 1982~. Because infectious disease has long been recognized as a serious threat, the military has, through painful lessons, developed effective strategies to address these threats. At least in the most recent declared war, the Gulf War, the strate- gies used to reduce risks from infectious disease and severe climate proved suc- cessful. In contrast to previous experiences, infectious diseases were not a major cause of lost personnel, even though many infectious diseases that pose serious health threats are endemic to the region of deployment (Hyams et al., 1995~. Although diarrhea! disease was common during the rapid buildup of Gulf War troops from August to September 1990, the majority of troops experienced mild traveler's-type diarrhea that resolved spontaneously (Hyams et al., 1995~. Gastroenteritis rates also dropped dramatically when fresh produce was elimi- nated from troops' diets (Hyams et al., 1995~. No cases of sandily fever were observed in Gulf War troops, and only seven cases of malaria were reported, and these were among troops who had crossed into southern Iraq. Twelve cases of visceral leishmaniasis and 20 cases of cutaneous leishmaniasis were diagnosed. In general, careful control of the water and food supplies, inspection of food preparation facilities, and use of insecticides and medical prophylaxes through immunizations seem to have been good defenses against infectious disease. This protection was facilitated by the isolation of the troops and the fact that most troops were deployed during the cold winter months, when sandfly and other arthropod activity is limited. Infectious diseases remain among the serious threats to deployed military forces. Although the military has exerted tremendous effort in countering these threats and understands them well, the ever-changing and evolving nature of infectious diseases will require continued vigilance and development of preven- tive methods. Multidrug-resistant malaria, increasingly widespread dengue epi- demics, hantavirus infections, and other hemorrhagic fevers are among the cur- rent diseases that may be encountered during future deployments, for which vaccines are not available, and against which complete protection may be diff~- cult or impossible to achieve by current methods.

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RISKS TO DEPLOYED FORCES 23 NON-BATTLE INJURIES Non-battle injuries (injuries sustained in non-combat aspects of a deploy- ment, such as in motor vehicles accidents and during training) have historically been a significant hazard for deployed troops. In past conflicts, rates of such injuries have frequently rivaled those from battle injuries and wounds (Table 2- 1) (F. D. Jones, 1995b). In the Gulf War, 55 of the 65 non-battle-related deaths resulted from accidental injuries, including two helicopter crashes and an acci- dent involving a light armored vehicle (Helmkamp, 1994~. Although total DNBI rates have fluctuated slightly between 5 and 10 per 100 soldiers per week during the major deployments in the last decade (Table 2- 2), injury has been among the top contributors in all of these deployments. In the Gulf War, 18.4 percent of all DNBI were injuries, whereas in the Somalia and Bosnia deployments, 25.2 and 27 percent of DNBI were injuries (McKee et al, 1998; U.S. Army Center for Health Promotion and Preventive Medicine, 1998~. In Southwest Asia since 1996, orthopedic injuries, both sports-related and other, have contributed 23.1 percent of DNBI cases (Thompson, 1999~. TABLE 2-1. Battle Injury and Wound Rates per 1,000 Troops per Year During Various U.S. Wars War No. of Non-Battle- No. of Battle-Related Year Related Injuries Injuries and Wounds U.S. Civil War 1861-1865 97 World War I 1917-1918 238 World War II Pacific 1942-1945 122 39 Europe 1942-1945 101 108 Mediterranean 1942-1945 131 80 Korea 1950 242 460 1951 151 170 1952 102 57 Vietnam 1965 67 62 1966 76 75 1967 69 84 1968 70 120 1969 63 87 SOURCE: F. D. Jones, 1995b.

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24 STRATEGIESTOPROTECTTHEHEALTHOFDEPLOYED U.S. FORCES TABLE 2-2. Average Disease and Non-Battle Injury (DNBI) Rates for Recent Deployments Deployment Person- Rate Service weeks (/O/week) Operation Desert Shield/ Storm Army1,242,300 5.8 (Gulf Wary Operation Desert Shield/ Storm Marine Corps787,310 6.5 (Gulf Wary Somaliaa Tri-Service163,093 10.6 Operation Joint Endeavor Tri-Service495,528 7.1 ~ 1995-1996) Operation Joint Guard ~ 1997)a Tri-Service453,002 8.1 Southwest Asia Operations Tri-Service1,576,738 5.2 ~ 1996-~ Operation Allied Force ~ 1999)b Air Force63,483 8.1 SOURCES: aMcKee et al., 1998; U.S. Army Center for Health Promotion and Pre ventive Medicine, 1998; McKee, 1999. bThompson, 1999. Data are as of May, 1999. Military rates of hospitalization for injuries, independent of deployments, are quite high and well above the goal specified in Healthy People 2000 (Bray et al., 1999; Public Health Service, 1991~. The high rates have recently prompted interest from the Injury Prevention and Control Work Group of the Armed Forces Epidemiologic Board. The group identified sports-related injuries, motor vehicle-related injuries, and falls or jumps as major causes of hospitalization for injury among military personnel and recommended research focused upon pre- vention (Injury Prevention and Control Work Group, 1996~. Heat and Cold Injuries Injuries from exposure to heat, cold, and other environmental factors can constitute important components of non-battle injuries. Injuries that occur as a result of exposure to excessive heat include heat rash, sunburn, heat cramps, heat exhaustion, and heat stroke. They made up less than 1 percent of DNBI during the Gulf War deployment, 2.3 percent during the Somalia deployment, and less than 1 percent during the Bosnia operations (U.S. Army Center for Health Promotion and Preventive Medicine, 1998; McKee et al., 1998~. In Southwest Asia Operations, they have contributed roughly 1 percent of overall DNBI cases since 1996 (Thompson, 1999~. Commanders have the most critical role in prevention of heat injuries through enforcement of physical fitness re- quirements, heat acclimation procedures, work and rest schedules, the appropri- ate use of clothing and equipment, and adherence to proper nutrition (U.S. Army

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RISKS TO DEPLOYED FORCES 25 Research Institute of Environmental Medicine and Walter Reed Army Institute of Research, 1994; Withers et al., 1994~. Among the many cold exposure-related injuries of military significance, trenchfoot, frostbite, and hypothermia are the most common in the military. Al- though injuries due to cold exposures were not recorded in detail until World War I, historically, many U.S. Army personnel who were exposed to cold envi- ronments during a deployment experienced cold-related injuries. For example, 10 percent of the U.S. wounded Army personnel in both World War II and Ko- rea suffered from cold-related injuries (Hamlet, 1987~. Commanding officers of every Army unit were responsible for making sure that the soldiers wore dry socks, changed their shoes or boots regularly, rubbed their feet with animal fat at least once a day, and exercised their feet to provide proper circulation (Whayne and DeBakey, 1958~. As with heat-related injuries, aggressive leadership will continue to be required for prevention of cold-related injuries in cold climates. PSYCHOLOGICAL STRESS Psychological stress is an important potential source of military casualties both during combat and in the years that follow. Especially since the Vietnam War it has been recognized that the stress accompanying combat can have both acute and chronic effects. Acute or short-term stress reactions have gone by many names, as noted below. Posttraumatic stress disorder (PTSD) is the name formalized in 1980 for long-term reactions to war-zone exposure (American Psychiatric Association, 1980~. Acute psychiatric casualties were first recognized as a significant source of personnel loss in battle in World War I. Most neuropsychiatric casualties in World War I were given the popular label "shell shock." By 1917, one-seventh of all discharges for disability from the British Army had been due to mental conditions. Of 200,000 soldiers on the pension list of England, one-f~fth suffered from war neurosis (Salmon, 1929~. Soon, physicians discovered the importance of forward and rapid treatment, that is, that patients with war neuroses improved more readily when they were treated near the front and were more likely to im- prove if they were treated quickly (Salmon, 1929~. Eventually, three principles became the critical elements of combat psychiatric casualty treatment: proxim- ity, immediacy, and expectancy. The most effective procedure was found to be the treatment of the combat psychiatric casualty in a safe place as close to the battle scene as possible (~proximity), as soon as possible (immediacy), and with explicit understanding that he was not ill and would soon be rejoining his com- rades (expectancy) (Artiss, 1963~. The treatment was to be simple, such as rest, food, and maybe a warm shower. Once it became clear that shell shock was not caused by the concussion of shelling, "war neurosis" was used as the diagnosis for the acute psychiatric casu- alty in World War I. Eventually, medical personnel were told to identify such casualties as "N.Y.D. (nervous)," for "not yet diagnosed (nervous)," which did not

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26 STRATEGIESTOPROTECTTHEHEALTHOFDEPLOYED U.S. FORCES suggest that it should be incapacitating or require hospital treatment. In World War II, the term "combat fatigue" came to be preferred (F. D. Jones, 1995a). In World War II, planners operated on the belief that preinduction screening could minimize potential psychiatric casualties (Glass, 1966a). Draft registrants with any significant history of psychiatric disturbance, especially those with anxiety symptoms, were not selected for service. Soldiers who showed symp- toms after induction were discharged. Manifestation of psychiatric symptoms provided an honorable way of avoiding induction, producing a massive loss of potential personnel (F. D. Jones, 1995a). Yet, even though the disqualification rate of registrants was about 7.6 times as high as that in World War I (1.6 mil- lion registrants were classified as unfit because of mental disease or educational deficiency in World War II), separation rates for psychiatric disorders were 2.4 times as high (Glass, 1966b). In addition to proving to be ineffective in preventing breakdown, the liberal separation policy for those with neurotic symptoms led to major personnel losses. Glass (1966b) noted that in September 1943, more soldiers were being eliminated from the U.S. Army than were being brought in and most of those separated were for psychoneuroses (35.6/1,000/year). Military psychiatrists con- cluded that reliance on psychiatric screening was ineffective, with studies indi- cating more similarities than differences between acute psychiatric casualties and their fellow soldiers (Glass, 1973; F. D. Jones, 1995a). Epidemiologic studies of World War II combat stress casualties indicated that they had a direct relationship to the intensity of combat and were modified by physical and morale factors (Beebe and DeBakey, 1952~. A notable study by Beebe and Appel (1958) indicated a breaking point for the average rifleman in the Mediterranean Theater of Operation of 88 days of company combat days in which the company sustained at least one casualty. Noy's review of that work found that psychiatric casualties had remained in combat duties longer than medi- cal and disciplinary cases and that their breakdowns were related to exposure to battle trauma more than medical and disciplinary cases were (Noy, 1987~. The importance of group cohesion in possibly preventing and treating psy- chiatric breakdown was another lesson of World War II. In his summary of les- sons learned in neuropsychiatry in World War II, Glass writes, Perhaps the most significant contribution of World War II military psychiatry was recognition of the sustaining influence of the small combat group or par- ticular members thereof, variously termed "group identification," "group cohe- siveness," "the buddy system," and "leadership." This was also operative in noncombat situations. Repeated observations indicated that the absence or in- adequacy of such sustaining influences or their disruption during combat was mainly responsible for psychiatric breakdown in battle. These group or rela- tionship phenomena explained marked differences in the psychiatric casualty rates of various units who were exposed to a similar intensity of battle stress. The frequency of psychiatric disorders seems to be more related to the charac- teristics of the group than to the character traits of the involved individuals. Thus, WWII clearly showed that interpersonal relationships and other social

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RISKS TO DEPLOYED FORCES and situational circumstances were at least as important as personality conf~gu- ration or individual assets and liabilities in the effectiveness of coping behavior. (Glass, 1973, p. 995) 27 The overall incidence of combat stress casualties in modern warfare has ranged from 10 to 25 percent of all combat casualties (Mareth and Brooker, 1985), but the incidence has been much higher in certain instances. In the 1973 Yom Kippur War, Israel suffered acute combat stress casualties at rates estimated to be from 30 to 50 percent (F. D. Jones, 1995a). The rate of combat stress casualties was highest among support personnel, probably responding to the trauma of see- ing dead and mutilated comrades. In the 1982 Lebanon War, the rate of casualties from acute stress was estimated at 23 percent (F. D. Jones, 1995b). The experiences of Vietnam veterans brought the first widespread recognition of delayed or chronic PTSD in deployed forces. People diagnosed with PTSD are characterized by symptoms of increased arousal, sudden reliving of a traumatic event through recurrent and intrusive recollections or dreams, and avoidance of stimuli associated with the trauma (American Psychiatric Association, 1994~. The National Vietnam Veterans Readjustment Study (NVVRS) was a com- prehensive national study of the postwar psychological problems of Vietnam veterans, mandated by the U.S. Congress in P.L. 98-160 (Kulka et al., 1990~. The study indicated that 15.2 percent of all male Vietnam theater veterans and 8.5 percent of female Vietnam theater veterans had current cases of PTSD. Among men and women with high levels of war-zone exposure, current PTSD was higher: 35.8 percent among men and 17.5 percent among women. An addi- tional 11.1 percent of male and 7.8 percent of female veterans suffered from "partial PTSD" symptoms that are of insufficient intensity or breadth to qual- ify as PTSD but that may still warrant professional attention. NVVRS analyses of the lifetime prevalence of PTSD indicated that almost one-third of male and more than one-fourth of women Vietnam theater veterans had PTSD at some time during their lives (Kulka et al., 1990~. Deployed populations in earlier wars also experienced the chronic effects of combat stress. Futterman and Pumpian-Mindlin (1951) reported a 10 percent prevalence of "war neurosis" in a series of 200 psychiatric patients seen in 1950. Another study observed "gross stress syndrome" in World War II veterans up to 20 years after combat (Archibald and Tuddenham, 1965~. After PTSD was rec- ognized in the 1980s, additional studies were carried out to assess PTSD in World War II and Korean War veterans. Although the prevalence of PTSD in older veterans is unknown, World War II veterans were similar to Vietnam vet- erans in their reactivity to stimuli reminiscent of their war trauma (Orr et al., 1993~. An additional study indicated current PTSD prevalences of 37 percent among World War II veterans and 80 percent among Korean War veterans among those who had previously sought psychiatric treatment (Blake et al., 1990; Friedman et al., 1994~. In a sample of 1,210 veterans of World War II and the Korean War, the prevalence of PTSD ranged from 0 to 12.4 percent de- pending on the PTSD measure (Spiro et al., 1994~.

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28 STRATEGIES TO PROTECT THE HEALTH OF DEPLOYED U.S. FORCES During the Gulf War, acute psychiatric casualties were rare. Only 6.5 per- cent of all medical evacuations from Southwest Asia during the Gulf War were classified as being for psychiatric reasons (Stretch et al., 1996~. Since the Gulf War, many different studies have been carried out to estimate the prevalence of PTSD in various groups of Gulf War veterans, with a range of PTSD prevalence reported from 4 to 36 percent (Sutker et al., 1993; Wolfe et al., 1993) (several studies have been critiqued and summarized by Haley t19974~. A telephone sur- vey of a large population-based sample of Gulf War veterans found that 1.9 per- cent reported symptoms of PTSD, whereas 0.8 percent of the military population deployed elsewhere during the same time reported symptoms of PTSD (Iowa Persian Gulf Study Group, 1997~. Military personnel on peacekeeping as well as combat deployments are at risk of long-term effects from psychological stress. A survey of a large cohort of military personnel deployed to Somalia for peacekeeping duty found that 8 per- cent met the diagnostic criteria for PTSD roughly 5 months after their return (Litz et al., 1997~. Even when deployment stress does not result in PTSD, it appears to result in increased levels of general psychological distress among deployed forces. Psychological symptom measures for samples of soldiers during deployments to operations in the Persian Gulf, Somalia, and Bosnia indicated that they had sig- nif~cantly elevated levels of psychological distress compared with those for non- deployed soldiers (Stuart and Halverson, 1997~. The deployment missions (combat, peacekeeping) themselves are not the only sources of stress for deployed military personnel. In a recent health survey of Department of Defense (DoD) personnel, the most frequently cited source of stress for both men and women was being away from family (reported by 19.5 percent of both men and women) (Bray et al., 1999~. Chapter 7 discusses further some of the varied sources of stresses relating to deployment and separation from family as well as reintegration into the home environment. Strategies for protecting forces from combat and deployment stress in future deployments must take into account the range of missions and environments that they will likely encounter. Clearly, these stresses cannot be eliminated, but some of their effects may be mitigated. High-intensity warfare, low-intensity warfare, peacekeeping, and humanitarian deployments each pose different challenges and mixes of psychological stressors (F. D. Jones, 1995c), so the preventive response requires flexibility, adaptability, and improvisation (Belenky and Martin, 1996a). As with other risks to the health of deployed troops, commanders must be aware of them and must be prepared to address and prevent them to the extent possible. TOXIC INDUSTRIAL CHEMICALS Historically, preventive measures for deployed forces have focused on the pre- vention of acute risks to health that will affect the mission. Growing awareness of the potential long-term risks posed by environmental and occupational exposures in the United States has been accompanied by recognition that such hazards may be

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RISKS TO DEPLOYED FORCES 29 present during military deployments as well. The burning of oil wells in Kuwait during the retreat of the Iraqi Army during the Gulf War made clear that local in- dustrial sources can create hazards for deployed forces. Troops may be exposed to hazardous chemicals through inadequate environmental protection in the area of operations, industrial accidents, sabotage, or the intentional or unintentional actions of other forces (Life Systems Inc. and GeoCenters Inc. for U.S. Army Center for Environmental Health Research, 1997~. Since military attention to these exposures is recent, their toll on deployed forces from previous wars is unknown. Improved envi- ronmental surveillance and exposure assessment are planned to provide a better un- derstanding ofthe risks for deployed forces National Research Council, l999b). At the same time, improvements in medical surveillance and record keeping after de- ployments (discussed in Chapters 4 and 5) will be needed to note any long-term ef- fects from environmental exposures. CHEMICAL WEAPONS The proliferation of chemical warfare capability among potential adversar- ies in recent years and the potential effects of chemical warfare agents on U.S. military forces are causes of serious concern. During future deployments, U.S. military forces are increasingly likely to confront opponents with chemical weapons capability. Other sections of this study (National Research Council, l999a,b,c) address the overall threat and risk assessment and the capability of the military to detect the agents used in chemical weapons and to protect mili- tary personnel using avoidance, protective masks, and clothing. Potential expo- sure to chemical weapons will have medical consequences that must be recog- nized and managed even if protective measures are used appropriately and minimal or no acute casualties result. The combined effects of low-level expo- sures, whether suspected or confirmed, and the stress of dealing with a chemical attack will create a need for risk communication, intensive long-term surveil- lance, careful analysis of medical outcomes, and skillful medical management of the affected personnel. BIOLOGICAL WEAPONS Like chemical weapons, biological weapons are an increasing concern be- cause of their intensive development by the former Soviet Union and Iraq and their proliferation to other potential adversaries. The list of potential agents in- cludes bacteria such as those that cause anthrax, plague, and tularemia; viruses, such as smallpox and neurotropic alphaviruses; rickettsiae; and biologic toxins. Although protection against aerosols is afforded by current equipment (masks), the difficulty of detecting and identifying biologic agents in aerosols has limited the effectiveness of detection equipment (National Research Council, l999b). For the foreseeable future DoD must rely heavily on prophylactic vaccines and drugs and must be prepared to deal with the long- and short-term medical effects

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30 STRATEGIESTOPROTECTTHEHEALTHOFDEPLOYED U.S. FORCES experienced by casualties exposed to biological weapons. Immunization of all military personnel with the currently licensed anthrax vaccine has greatly re- duced the threat of anthrax which has widely been regarded as the most effective and imminent biologic threat. PROTECTIVE MEDICATIONS Some of the potential risks to deployed forces include the protective medi- cations themselves. Although protective medications are selected because they can help protect service members in dangerous environments, they can have risks of their own. In many cases, the benefits have been thoughtfully and thor- oughly weighed against these risks. The use of DEET (diethyl m-toluamide) as a mosquito repellent is an example. DEET carries a slight risk of neurotoxicity when used at high doses and has been associated with rare deaths in susceptible people. It is considered safe enough for over-the-counter sale to civilians, how- ever, and is far less hazardous to service members than mosquito bites in areas where malaria is endemic. One of the studies carried out concurrently with this study further addresses a framework for assessing risks to deployed forces (Na- tional Research Council, 1999a). INTERACTIONS In addition to the separate risks posed by each of the exposures described above, the potential for additive or synergistic effects of such exposures has be- come a source of concern. During deployments, military personnel are exposed to combinations of drugs, biologics, and chemicals to which civilians are not exposed. As in civilian settings, the health effects of exposures to these mixtures are poorly characterized, but the diversity and number of agents preclude testing of all possible combinations or the development of reliable predictors of all pos- sible interactions that could result in increased toxicity (Institute of Medicine, 1996b). The Institute of Medicine Committee to Study the Interactions of Drugs, Biologics, and Chemicals in U.S. Military Forces included in its recommenda- tions enhanced surveillance systems, a battery of experimental studies, and care- ful epidemiologic studies (Institute of Medicine, 1996b). The risks described in this chapter are ones that have been recognized to various degrees by the military leadership and preventive medicine community. The next chapter discusses another aspect of health risks to deployed forces that is a particular focus of this study because it has not yet been addressed by the military with a prevention or mitigation strategy.