EMS and Medical Surveillance

     Terrorism preparedness has become a reality. Many EMS systems have made changes to improve their responses to terrorism that have also improved their daily operations. These include increased use of personal protective equipment (particularly respiratory protection), scene awareness, and decontamination and care of the hazmat patient.

     Part of EMS terrorism preparation is establishing relationships with public health. Public health, rather than EMS, is primarily responsible for bioterrorism events. Bioterrorism may be difficult to differentiate from common diseases, and victims may be far from the site of their exposure before becoming ill. With emergency departments overcrowded and understaffed, EMS systems running at peak capacity and the primary care system strained, an uncommon disease marking a bioterrorism event may not be detected early in its course.

     Public health performs surveillance of community health and disease. This surveillance is also used as a tool in the early detection of and response to bioterrorism. Although some regions may have effective real-time syndromic surveillance systems, most do not. There is a lack of state and national coordination of surveillance systems that leads to gaps in the critical disease monitoring and prevention process.

     EMS commonly uses sophisticated information technology resources, particularly in public safety access points and dispatch centers. These resources have allowed some EMS agencies to participate in syndromic surveillance. These organizations participate in regional, state, and national bioterrorism surveillance activities while using the data for their own specific projects.

Surveillance
     Surveillance is the monitoring of a population for changes from a predetermined norm or standard, with notification of appropriate individuals if a change is noted.1 Medical surveillance (or biosurveillance) systems look at the health and disease status of a population. They detect and analyze diseases or symptom clusters (syndromes) to see if they are occurring more often than would be normally expected.

     For a surveillance system to work, you need to know how often a specific event actually occurs in your community (a baseline standard). For example, the baseline standard for smallpox is that there are no cases. A single case would be considered a terrorist event and a national public health emergency. Viral gastroenteritis, on the other hand, is so common that a large increase above the baseline would be necessary before it could be considered unusual.

     Surveillance systems must look for "important" diseases or syndromes and be able to detect changes from the baseline. The way a case is defined (signs and symptoms, clinical findings and laboratory studies) greatly influences the surveillance system. During influenza season, for example, it could be almost impossible to tell inhalational anthrax from influenza if the anthrax case definition were "fever and respiratory symptoms." That is why the CDC case definition includes the chest x-ray findings of widened mediastinum-and that's why surveillance systems must monitor for that result as well. Otherwise, the anthrax case probably would not be recognized by the surveillance system. In addition, a new disease like SARS might not be identified as unusual if it weren't different from other similar diseases (e.g., influenza, pneumonia) in terms of severity, symptoms, mortality or season of presentation.

     Surveillance systems must also notify the appropriate individuals quickly. Most health departments receive notable laboratory results as they become available but do not have around-the-clock staffing, so response delays may exist. These public-health surveillance systems are not real-time and are slow to process information, resulting in delays in detection. Although these delays may be fine for traditional diseases, they are unacceptable for highly communicable bioweapons in the era of rapid world travel. There are EMS systems using continuous call data monitors (described below) that achieve near real-time surveillance. Additionally, a few emergency department-based systems and "drop-in" surveillance systems at special events have almost-real-time capability.