An effective military medical surveillance system needs to collect reliable information on (1) the health care provided to service members before, during, and after deployment, (2) where and when service members were deployed, (3) environmental and occupational health threats or exposures during deployment (in theater) and appropriate protective and countermeasures, and (4) baseline health status and subsequent health changes. This information is needed to monitor the overall health condition of deployed troops, inform them of potential health risks, as well as maintain and improve the health of service members and veterans. In times of conflict, a military medical surveillance system is particularly critical to ensure the deployment of a fit and healthy force and to prevent disease and injuries from degrading force capabilities. DOD needs reliable medical surveillance data to determine who is fit for deployment; to prepare service members for deployment, including providing vaccinations to protect against possible exposure to environmental and biological threats; and to treat physical and psychological conditions that result from deployment. DOD also uses this information to develop educational measures for service members and medical personnel to ensure that service members receive appropriate care. Reliable medical surveillance information is also critical for VA to carry out its missions. In addition to VA’s better known missions—to provide health care and benefits to veterans and medical research and education— VA has a fourth mission: to provide medical backup to DOD in times of war and civilian health care backup in the event of disasters producing mass casualties. VA needs reliable medical surveillance data from DOD to treat casualties of military conflicts, provide health care to veterans who have left active duty, assist in conducting research should troops be exposed to environmental or occupational hazards, and identify service- connected disabilities to adjudicate veterans’ disability claims. Investigations into the unexplained illnesses of service members and veterans who had been deployed to the Persian Gulf uncovered the need for DOD to implement an effective medical surveillance system to obtain comprehensive medical data on deployed service members, including Reservists and National Guardsmen. Epidemiological and health outcome studies to determine the causes of these illnesses have been hampered by a lack of (1) complete baseline health data on Gulf War veterans; (2) assessments of their potential exposure to environmental health hazards; and (3) specific health data on care provided before, during, and after deployment. The Presidential Advisory Committee on Gulf War Veterans’ Illnesses’ and IOM’s 1996 investigations into the causes of illnesses experienced by Gulf War veterans confirmed the need for more effective medical surveillance capabilities. The National Science and Technology Council, as tasked by the Presidential Advisory Committee, also assessed the medical surveillance system for deployed service members. In 1998, the council reported that inaccurate recordkeeping made it extremely difficult to get a clear picture of what risk factors might be responsible for Gulf War illnesses. It also reported that without reliable deployment and health assessment information, it was difficult to ensure that veterans’ service-related benefits claims were adjudicated appropriately. The council concluded that the Gulf War exposed many deficiencies in the ability to collect, maintain, and transfer accurate data describing the movement of troops, potential exposures to health risks, and medical incidents in theater. The council reported that the government’s recordkeeping capabilities were not designed to track troop and asset movements to the degree needed to determine who might have been exposed to any given environmental or wartime health hazard. The council also reported major deficiencies in health risk communications, including not adequately informing service members of the risks associated with countermeasures such as vaccines. Without this information, service members may not recognize potential side effects of these countermeasures or take prompt precautionary actions, including seeking medical care. In response to these reports, DOD strengthened its medical surveillance system under Operation Joint Endeavor when service members were deployed to Bosnia-Herzegovina, Croatia, and Hungary. In addition to implementing departmentwide medical surveillance policies, DOD developed specific medical surveillance programs to improve monitoring and tracking environmental and biomedical threats in theater. While these efforts represented important steps, a number of deficiencies remained. On the positive side, the Assistant Secretary of Defense (Health Affairs) issued a health surveillance policy for troops deploying to Bosnia. This guidance stressed the need to (1) identify health threats in theater, (2) routinely and uniformly collect and analyze information relevant to troop health, and (3) disseminate this information in a timely manner. DOD required medical units to develop weekly reports on the incidence rates of major categories of diseases and injuries during all deployments. Data from these disease and non-battle-injury reports showed theaterwide illness and injury trends so that preventive measures could be identified and forwarded to the theater medical command regarding abnormal trends or actions that should be taken. DOD also established the U.S. Army Center for Health Promotion and Preventive Medicine—a major enhancement to DOD’s ability to perform environmental monitoring and tracking. For example, the center operates and maintains a repository of service members’ serum samples—the largest serum repository in the world—for epidemiological studies to examine potential health issues for services members and veterans. The center also operates and maintains a system for integrating, analyzing, and reporting data from multiple sources relevant to the health and readiness of military personnel. This capability was augmented with the establishment of the 520th Theater Army Medical Laboratory—a deployable public health laboratory for providing environmental sampling and analysis in theater. The sampling results can be used to identify specific preventive measures and safeguards to be taken to protect troops from harmful exposures and to develop procedures to treat anyone exposed to health hazards. During Operation Joint Endeavor, this laboratory was used in Tuzla, Bosnia—where most of the U.S. forces were located—to conduct air, water, soil, and other environmental monitoring. Despite the Department’s progress, we and others have reported on DOD’s implementation difficulties during Operation Joint Endeavor and the shortcomings in DOD’s ability to maintain reliable health information on service members. Knowledge of who is deployed and their whereabouts is critical for identifying individuals who may have been exposed to health hazards while deployed. However, in May 1997, we reported that inaccurate information on who was deployed and where and when they were deployed—a problem during the Gulf War—continued to be a concern during Operation Joint Endeavor.For example, we found that the Defense Manpower Data Center (DMDC) database—where military services are required to report deployment information—did not include records for at least 200 Navy service members who were deployed. Conversely, the DMDC database included Air Force personnel who were never actually deployed. In addition, we reported that DOD had not developed a system for tracking the movement of service members within theater. IOM also reported that during Operation Joint Endeavor, locations of deployed service members were still not systematically documented or archived for future use. We also reported in May 1997 that for the more than 600 Army personnel whose medical records we reviewed, DOD’s centralized database for postdeployment medical assessments did not capture 12 percent of those assessments conducted in theater and 52 percent of those conducted after returning home. These data are needed by epidemiologists and other researchers to assess at an aggregate level the changes that have occurred between service members’ pre- and postdeployment health assessments. Further, many service members’ medical records did not include complete information on the in-theater postdeployment medical assessments that had been conducted. The Army’s European Surgeon General attributed missing in-theater health information to DOD’s policy of having service members hand-carry paper assessment forms from the theater to their home units, where their permanent medical records were maintained. The assessments were frequently lost en route. We have also reported that not all medical encounters in theater were being recorded in individual records. Our 1997 report indicated that this problem was particularly common for immunizations given in theater. Detailed data on service members’ vaccine history are vital for scheduling the regimen of vaccinations and boosters and for tracking individuals who received vaccinations from a specific vaccine lot in the event that health concerns about the lot emerge. We found that almost one-fourth of the service members’ medical records that we reviewed did not document the fact that they had received a vaccine for tick-borne encephalitis. In addition, in its 2000 report, IOM cited limited progress in medical recordkeeping for deployed active duty and reserve forces and emphasized the need for records of immunizations to be included in individual medical records. Responding to our and others’ recommendations to improve information on service members’ deployments, in-theater medical encounters, and immunizations, DOD has continued to revise and expand its policies related to medical surveillance, and the system continues to evolve. In addition, in 2000, DOD released its Force Health Protection plan, which presents the Department’s vision for protecting deployed forces and includes the goal of joint medical logistics support for all services by 2010. The vision articulated in this capstone document emphasizes force fitness and health preparedness, casualty prevention, and casualty care and management. A key component of the plan is improved monitoring and surveillance of health threats in military operations and more sophisticated data collection and recordkeeping before, during, and after deployments. However, IOM criticized DOD’s progress in implementing its medical surveillance program as well as its failure to implement several recommendations that IOM had made. In addition, IOM raised concerns about DOD’s ability to achieve the vision outlined in the Force Health Protection plan. We have also reported that some of DOD’s programs designed to improve medical surveillance have not been fully implemented. IOM’s 2000 report presented the results of its assessment of DOD’s progress in implementing recommendations for improving medical surveillance made by IOM and several others. IOM stated that, although DOD generally concurred with the findings of these groups, DOD had made few concrete changes at the field level. In addition, environmental and medical hazards were not yet well integrated in the information provided to commanders.