Biological weapons and emerging infectious diseases pose a significant risk to public health. A timely response is needed to effectively treat and contain a potential infectious disease outbreak. Detection and surveillance of biological agents needs to be sensitive and specific to allow providers to quickly and accurately identify the disease process and begin the necessary response procedures. This article addresses the importance of early detection and surveillance of both intentional and unintentional biological events. Challenges of bioterrorism and the nursing role in response are discussed. Epidemiological considerations, such as route of transmission and personal protective equipment, are presented. An overview of the major surveillance systems, including advances in computer-based technology, is provided to help health care providers become aware of current surveillance systems and clinical decision support tools designed to help diminish the impact of biological threats.
Key words: biological terrorism, biological weapons, early detection, epidemiology, isolation precautions, infectious diseases, nursing, surveillance, technology
The events of September 11, 2001 and the October 2001 anthrax attacks heightened awareness of the possible threat of biological terrorism. As a result, national security has increased, with a focus toward the use of unconventional weapons on civilians. Such acts of terrorism would pose unique challenges for our health care system, which would have to accommodate and effectively handle not only short-term and long-term health problems resulting from exposure to toxic agents, but also the fear and panic of the public (Alexander & Hoenig, 2001).
...biological agents that can be used for biological warfare [and] infectious diseases found in nature present challenges to public health officials.
In addition to biological agents that can be used for biological warfare, infectious diseases found in nature also present challenges to public health officials. Recently, the incidence of emerging infectious diseases, such as severe acute respiratory syndrome (SARS), bovine spongiform encephalopathy (BSE), avian influenza, and monkeypox, and the re-emergence of mutated diseases, such as tuberculosis, have increased. The arrival of these pathogens creates an additional burden on clinicians to recognize, diagnose, and manage a disease they may not have previously encountered.
In the event of a biological event of either type, nurses, the largest sector of the health care workforce, will be called upon to care for patients. The most effective response to a major attack will depend on nurses’ ability to quickly detect the presence of infectious diseases. This article discusses challenges of bioterrorism and the nursing role in response. A brief overview is provided of infectious disease epidemiology, safety issues in patient management, and use of personal protective equipment. Surveillance concerns and new advances in technology are introduced that may contribute to a nurse’s ability to participate in early detection efforts.
Challenges of Bioterrorism
Definition and History
Bioterrorism can be defined as "the intentional release, or threatened release, of disease-producing living organisms or biologically active substances derived from organisms for the purpose of causing death, illness, incapacity, economic damage, or fear" (Weinstein & Alibek, 2003, p. 2). There are many different types of biological agents, including bacteria, viruses, fungi, genetically altered or enhanced infectious agents, vaccine and/or multi-drug resistant organisms, and toxins which are produced from organisms, but which resemble chemical agents (Weinstein & Alibek, 2003).
Use of unconventional weapons for the purpose of biological warfare has been reported throughout the centuries. In the 1300s, the Tatars catapulted plague-infected bodies at their enemies, the Geonese, to capture the Black Sea port of Kaffa. During the French and Indian War, more than four-hundred years later, British troops gave smallpox-infested blankets to unsuspecting American Indians (McGovern & Christopher, 1995-2001). Most recently during the Cold War, both the United States and the Soviet Union produced and stockpiled massive biological weapons arsenals, such as smallpox and anthrax (Davis, 1999; Keyes, Burstein, Schwartz, & Swienton, 2005). Today, more than a decade since the end of the Cold War, the threat of biological weapons remains a daunting reality.
Importance of Early Detection
Early detection and surveillance of infectious disease outbreaks are critical components of preparation for potential biological attacks.
Early detection and surveillance of infectious disease outbreaks are critical components of preparation for potential biological attacks. In contrast to chemical terrorism, in which effects are usually immediate and obvious, an attack using a biological agent is not likely to have an immediate impact due to the incubation period of the organism (Veenema, 2003). Disease surveillance systems must be capable of detecting unusual patterns of disease or injury, and officials at the local, state, and federal levels must have the knowledge and resources to respond effectively to reports of rare or unexplained illnesses. Therefore, timeliness is a critical component to early detection and surveillance of infectious diseases. Tables 1 and 2 provide an overview of the different biological organisms that could be employed in a bioterror attack and those that are found in nature, respectively.
Early recognition and detection of infectious diseases is important for two reasons. First, it allows providers to administer effective prophylactic treatment in
...bioterrorism is not easy to detect...early diagnosis of patients infected with a biological agent is complicated by the fact that symptoms of many biological agents resemble those of the flu.
a timely manner, and second, it minimizes the opportunity for transmission of the agent (Veenema, 2003). In the case of a terrorist event, there are two kinds of attacks to consider: an announced attack and an unannounced attack. In an announced attack, the terrorist publicly discloses the agent that was used, which allows providers and public health officials to be more attuned to detecting and diagnosing cases. In an unannounced attack, however, detection and identification of the agent would not take place until after patients begin to present in the emergency department (ED) and physician offices. This latter scenario results in time lost that the providers could have used to locate and treat new cases.
Even if patients present in the ED, bioterrorism is not easy to detect. Early diagnosis of patients infected with a biological agent is complicated by the fact that symptoms of many biological agents resemble those of the flu. Moreover, many providers in the United States lack clinical experience with most of the agents that could be used as weapons. This is further complicated by the possibility that terrorists are not limited to the use of a single agent, or for that matter, a known agent. The result could be clusters of patients who present with similar symptoms, but different illnesses.
Nursing Role in Surveillance
In remaining vigilant for the presence of a new disease, the individual nurse functions as a 'mini-surveillance system.'
Nurses, who are frequently the first contact a patient has with the health care system, may find themselves identifying the presence of infectious diseases, tracking and identifying cases, notifying the proper authorities and implementing disease containment programs. In remaining vigilant for the presence of a new disease, the individual nurse functions as a ‘mini-surveillance system.’ In fact, an astute clinician is a critical component of any national surveillance system. The first lines of detection of a biologic agent released into the population reside with a physician or nurse who diagnoses an individual with signs and symptoms of that biologic agent (Rotz et al., 2000).
The specific role of the individual nurse will probably be determined by place of employment and the health care needs of the population of patients being seen. However, all nurses should be familiar will the fundamental concepts of epidemiology, early detection, and surveillance, and appreciate the role of the nurse in contributing to the success of this system. Even nurses who do not work in situations directly related to public health should appreciate that they may be contributing to surveillance data collection systems. Each time a nurse enters a patient variable into emergency department records or electronic medical records (EMRs), that data may be used for surveillance purposes. The following section provides an overview of basic concepts of epidemiology, early detection, and surveillance.
Infectious Disease Epidemiology
The field of epidemiology has been defined as "the study of the distribution and determinants of health-related states or events in specified populations, and the application of this study to the control of health problems" (Last, 2001). There are three components to this definition. The first involves the examination of what health problems arise, who is affected by them, and when and where they occur. The second component attempts to address how and why the observed patterns of disease occur. The final element involves the control and prevention of disease processes.
The disease process is often described by epidemiologists as the epidemiological triangle or triad (Gordis, 2004). According to this model, disease occurs as a result of the interaction of three elements: an agent, a host, and an environment. Various types of agents can cause disease. These include biological agents such as bacteria or viruses; chemical agents such as nerve agents and vesicants; and physical factors such as radiation, heat, or trauma (Gordis, 2004; Weinstein & Alibek, 2003). Some host factors, such as age and immune status, can affect susceptibility to an agent. Other host characteristics, such as occupation or dietary customs, can affect the potential for exposure to an agent (Centers for Disease Control and Prevention [CDC], 1992). Environmental factors that can facilitate interaction between the agent and host include physical factors such as temperature and wind patterns; social factors such as the degree of crowding or sanitation; and biological factors such as the presence of vectors (e.g., mosquitoes) that can transmit a given biological agent (Mausner & Kramer, 1985). Food and water supplies are also part of the environment and may serve as the vehicle to transmit an infectious agent (Gordis, 2004; Harkness, 1995). See Table 3 for a more detailed list of factors in the epidemiological triad.
Routes of Transmission
Infection is the final step in the chain of events that results from introduction of the infectious agent into the susceptible host.
Infection is the final step in the chain of events that results from introduction of the infectious agent into the susceptible host (CDC, 1992). There are five main routes of transmission: contact, droplet, airborne, common vehicle, and vectorborne. Some diseases can be transmitted in more than one way, however, and different clinical manifestations may be seen depending on the route of entry into the host. Anthrax, plague, and tularemia are examples of potential bioterror agents that have different disease forms depending on the mode of transmission (Dennis et al., 2001; Inglesby et al., 1999, 2000; U.S. Army Medical Research Institute of Infectious Diseases [USAMRIID], 2001). The modes of infectious disease transmission are discussed briefly below.
Contact transmission. Contact transmission, the most frequent mode of transmission, can be further divided into two subgroups: direct-contact transmission and indirect-contact transmission. Direct-contact transmission involves a direct contact and physical transfer of microorganisms between an infected person and a susceptible host. Indirect-contact transmission involves contact of a susceptible host with a contaminated intermediate object, such as contaminated instruments or needles.
Droplet transmission. Droplet transmission occurs when the infected person expels droplets containing microorganisms, which are then inhaled by the host.
Airborne transmission. Airborne transmission occurs in two ways. Either airborne droplets containing microorganisms that remain suspended in the air for long periods of time, or dust particles containing the infectious agent, are inhaled by a susceptible host. This can occur within the same room or over a longer distance from the infected patient.
Common vehicle transmission. Common vehicle transmission occurs when microorganisms are transmitted by contaminated items such as food, water, or instruments.
Vectorborne transmission. Vectorborne transmission occurs when a microorganism is transmitted by vectors such as mosquitoes, flies, rats, and other vermin that transmit microorganisms.
Protection from Infectious Disease
Infectious diseases, especially those that could be used as a biological weapon, are highly contagious. Certain safety precautions need to be in place to protect both health care providers and the community from becoming victims of secondary contamination. Potential exposure to biological agents occurs through several means:
- Direct contact with a hazardous substance
- Liquid (droplets or aerosols)
- Inhalation of vapors or aerosols
In order to protect nurses and other health care personnel from being exposure to biological agents, isolation precautions have been established that are specific to different modes of transmission. There are four isolation precautions: standard, airborne, droplet and contact (Veenema, 2003). Health care providers and staff can also avoid exposure to hazardous agents by wearing personal protective equipment (PPE) when treating potentially infected patients. In the Code of Federal Regulations Section 1910, the Occupational Safety and Health Administration (OSHA) defines types of PPE and situations in which employees are required to wear PPE (U.S. Department of Labor, n.d.). Different types of PPE offer several levels of protection. Levels of protection, explained below, are designated A, B, C, and D.
Level A. Level A refers to a total encapsulating, chemical-resistant suit with a self-contained breathing apparatus, gloves, and boots. This suit provides complete protection from liquids and vapors.
Level B. Level B is often used when full respiratory protection is needed but the hazard from vapor is less. This form of PPE is not fully airtight, but it offers protection against liquids.
Level C. Level C uses a splash suit with a full-faced positive or negative breathing mask.
Level D. Level D consists of a work uniform using latex gloves. Mouth and eye protection is used if necessary.
Following OSHA guidelines can help providers protect themselves, coworkers, and the public from infection. Table 4 lists nursing implications related to isolation precautions and PPE. The next section discusses major surveillance systems in use, another important tool to diminish the impact of infectious disease threats.
Major Surveillance Systems
In an infectious disease outbreak...the purpose of a surveillance system is to enhance timely detection of the event.
Public health surveillance is "the ongoing, systematic collection, analysis, interpretation, and dissemination of health data" (CDC, 1998, para 1). There are many surveillance systems in place around the globe that provide a description or assessment of disease patterns in the population. International and national infectious disease surveillance systems are summarized in Table 5. In an infectious disease outbreak, either intentional or unintentional, the purpose of a surveillance system is to enhance timely detection of the event. Two approaches discussed below, the epidemiological and the syndromic, are used to help survey infectious diseases.
The epidemiological approach relies on data regarding mortality, morbidity, or other health indicators. These data are routinely collected as part of current surveillance systems in the United States and may be important in bioterror events (CDC, 1992). For instance, a rise in the number of deaths due to a flu-like illness could be an indicator of a naturally occurring outbreak or of a deliberate agent release (Franz et al., 2001). Other health indicator data, such as school absenteeism reports or death certificates, could also be useful to identify unusual events (Franz et al.; Veenema, 2003). Table 6 provides a list of epidemiological patterns that might indicate the presence of a biological attack.
The syndromic approach focuses on detection of clinical symptoms or syndromes that may be associated with bioterror agents. The CDC has identified certain agents and toxins that are considered to have a higher probability of use in a bioterror event, and has categorized these agents (Categories A, B and C) by how readily they can be disseminated, their potential for morbidity and mortality, and their burden on public health preparedness. The following are examples of syndromes and possible Category A agents associated with them (Veenema, 2003):
- Rapidly progressive pneumonia
- Neurologic syndrome
- Fever with rash
- Viral Hemorrhagic Fever
- Fever progressing to fulminant shock
- Viral hemorrhagic fever
Table 7 lists some examples of agents in Categories A, B, and C, with implications for protection from these biological agents.
...at times [surveillance] systems have still resulted in delayed identification of the agent [and]...has hindered notification of the agent to the necessary authorities.
Despite surveillance systems in place to detect infectious diseases, at times these systems have still resulted in delayed identification of the agent. This delay has hindered notification of the agent to the necessary authorities. Such a scenario occurred in 2002 when officials at the CDC and the World Health Organization (WHO) were unaware of the emergence of the SARS virus until nearly a month after it infected the initial patient. This was partially due to a reticence on the part of Chinese officials, as well as a difficulty in identification of the coronavirus in its early stages (Drosten, Doerr, Lim, Stohr, & Niedrig, 2004; U.S. GAO, 2004). Furthermore, certain strains of viruses undergo abrupt shifts in the major antigenic determinants of their surface proteins, thereby making it more difficult for laboratory tests to detect them (Effler, Ieong, Tom, & Nakata, 2002).
...certain strains of viruses undergo abrupt shifts...making it more difficult for laboratory tests to detect them.
Strains such as Influenza A could, as a result, go undetected for longer periods of time and thus infect more people. In 1918, for example, the new influenza A H1N1 virus strain resulted in over 20 million deaths worldwide (Effler, et al.).
Improvements are needed in technology to demonstrate increased clinical sensitivity, specificity and accuracy so that health care organizations and providers can detect and respond to epidemics rapidly and efficiently. Advances in diagnostic technologies discussed below are examples of current methods designed to improve response by decreasing the delay in identification of infectious diseases due to biological agents.
Advances in Diagnostic Technologies
Improvements in population-base and patient-specific diagnostic technologies need to be made to increase the accurate identification of infectious disease outbreaks and biological agents. Current software programs allow clinicians to enter patient specific findings and receive patient-contextualized information and diagnostic assistance to enhance surveillance and clinical decision-making. Examples of surveillance technology include the Early Aberration Reporting System (EARS) (CDC, 2005a), the North Carolina Disease Event Tracking and Epidemiologic Collection Tool (NC DETECT) (University of North Carolina, 2004-05), Epi-X (CDC, n.d.), FirstWatch® (Stout Solutions, 2003-05), and Infection Control Assistant™ (Theradoc Inc., 2000-05). Examples of clinical decision-support systems include VisualDx® (Logical Images, Inc., 2005), GIDEON (Gideon Informatics Inc., 1994-2005) and Isabel (Isabel Healthcare, 2005). A brief overview of each software program is provided below.
Early Aberration Reporting System. EARS (CDC, 2005a) is a web-based, adaptable syndromic surveillance tool used by public health officials in the United States and abroad. This tool analyzes syndromic data from emergency departments, 9-1-1 calls, and physician offices. The analyzed data might include signs and symptoms such as abdominal pain, breathing difficulty, or back pain. EARS can also incorporate school and business absenteeism data and data from over-the-counter drug sales into its analysis. Identified deviations in current data are compared to a historical (5-year) or non-historical (7-day) mean. The output includes tables, graphs, and maps that indicate geographic locations of aberrations. The EARS aberration detection measures appear sensitive enough to serve as an early warning system for bioterrorism events (CDC).
North Carolina Disease Event Tracking and Epidemiologic Collection Tool. NC DETECT (University of North Carolina, 2004-05) is an example of a unique source of information for public health surveillance, research, and clinical operations which allows users to quickly detect infectious diseases though secondary data sources compiled by the North Carolina Emergency Department Database. These data are then converted into tabular, graphical, and map-based results using the CDC’s Early Aberration Reporting System (discussed above).
Epi-X. Epi-X (CDC, n.d.) is a web-based preliminary health surveillance information source for pre-approved users, such as CDC officials, state and local health departments, poison control centers, and other public health professionals. Users of the system are notified routinely by email or emergently by pager, telephone, and email about breaking health events. When appropriate, Epi-X helps ensure accurate communications to the public through the Morbidity and Mortality Weekly Report (MMWR) and other sources.
FirstWatch®. FirstWatch® Real-Time Early Warning System (Stout Solutions, 2003-05) is a syndromic surveillance system that monitors 9-1-1 calls, law enforcement, fire, and emergency medical services data from computer aided dispatch (CAD), ProQA advanced telephone triage, and poison control center data for patterns that suggest a threat to public safety or health. It also can include hospital ED records, nurse-call triage information, hospital diversion data, and field data in the analysis of a potential threat. Users can customize the system’s real-time analysis to meet their region’s surveillance needs. In addition to alerts, output includes charts, graphs, and maps that indicate the distribution of suspicious events. In use in 16 states as of June 2005, FirstWatch® monitors population data for over 14 million people.
Infection Control Assistant™. Infection Control Assistant™ (Theradoc, Inc., 2000-05) helps hospital infection control professionals identify, quantify, and control community-acquired infectious outbreaks, antibiotic resistance, and nosocomial infections through surveillance and analysis of patient data from electronic medical records, pharmacies, laboratories, Admission/Discharge/Transfer records, and other electronic sources. Infection Control Assistant™ also includes customizable reports and cluster alerting.
Clinical Decision Support Tools
VisualDx®. VisualDx® Point-of-Care Diagnostic Software System (Logical Images, Inc., 2005) is an interactive decision support tool that assists clinicians in early detection, diagnosis, and treatment of visually diagnosable disease (e.g., infectious diseases, bioterrorism, chemical warfare, radiation injuries, common and rare dermatologic conditions, sexually transmitted diseases, travel-related diseases, oral diseases, and drug eruptions). The tool is used by the military, hospitals, EDs, public health departments, clinics, and infectious disease and primary care physician offices in the United States and abroad. VisualDx® merges a large database of professionally photographed images of disease presentation with clinical information to allow clinicians to build a custom, pictorial, differential diagnosis by entering their patients’ findings. In addition to the ability to compare images of the disease presentation in the differential diagnoses of their patients, clinicians can see multiple images related to each disease. This reveals the range in presentation within each disease, as well as variations due to such factors as skin type, age, or disease stage. Information about each disease also includes handbook length, text-guiding diagnosis, best tests, treatment, and patient management. A randomized, controlled university study showed that VisualDx® increased diagnostic accuracy over 100 percent (Unpublished abstract, 2001).
GIDEON. An acronym for "Global Infectious Disease & Epidemiology Network," GIDEON (Gideon Informatics Inc., 1994-2005) is an interactive software tool for diagnosis and reference of infectious disease, tropical disease, and bioterrorism. It also includes information on epidemiology, microbiology, and antimicrobial chemotherapy. In use in the United States and abroad by ED physicians, infectious disease specialists, hospitals, medical schools, public health departments, and the military ,GIDEON’s clinical decision support helps clinicians build a differential diagnosis based on patient findings and travel history. The epidemiology module tracks the real-time status of every disease in every country; describes each disease’s signs, symptoms, and laboratory abnormalities; and includes thousands of graphs, maps, and diagrams for use in presentations and lectures. Drug and vaccine treatment guidelines are also available in the GIDEON online tool.
Isabel. The Isabel diagnosis reminder system (Isabel Healthcare, 2005) is a web-based clinical decision support tool in use by physicians, hospitals, health systems, and medical schools in the United Kingdom, the United States and other international sites. To use the system, clinicians enter a patient’s clinical features (e.g., symptoms, signs, test results) and the system returns a checklist of likely diagnoses, as well as information from medical journals and medical textbooks on the conditions. The Isabel diagnosis reminder system includes differential diagnosis for internal medicine, surgery, gynecology, obstetrics, pediatrics, geriatrics, oncology, toxicology, and bioterrorism. A 2003 study found that the tool had a 95 percent accuracy rate (Ramnarayan et al., 2003). If desired, the system may be integrated with an electronic medical record (EMR) system or be accessed through a Personal Digital Assistant (PDA).
Recent advances in computer-based technologies enhance the possibility for health care organizations and providers to collect, disseminate, and share data.
Early detection of infectious diseases is necessary to minimize the number of people infected. Public heath surveillance is thus in a critical component to rapid identification and containment of biological agents. With the threat of bioterrorism and an increase in the emergence of both new and old infectious diseases, passive surveillance is ineffective in providing timely detection and identification of diseases. Recent advances in computer-based technologies enhance the possibility for health care organizations and providers to collect, disseminate, and share data. As a result of these systems, exotic and delayed-presentation diseases can be identified with greater ease, disease trends can be tracked, and providers can be alerted to a possible outbreak before further transmission occurs. Nurses and other providers should be familiar with basic epidemiological concepts and the surveillance and notification systems currently available to be prepared to recognize and respond to biological events in a timely manner.
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Tener Goodwin Veenema PhD, MPH, MS, CPNP
Tener Goodwin Veenema, PhD, MPH., MS, CPNP, is an Associate Professor of Nursing and Emergency Medicine at the University of Rochester School of Nursing and School of Medicine and Dentistry. She is also Program Director for Disaster Nursing and Strategic Initiatives at the Center for Disaster Medicine and Emergency Preparedness at the University of Rochester Health Sciences Center. Dr. Veenema has received several awards and research grants for her work, including the University of Rochester Faculty Service Advancement Award and the Sigma Theta Tau International Dissertation award in 2001. In May 2004, Dr. Veenema was elected into the National Academies of Practice and in June 2004 was selected as a Robert Wood Johnson Nurse Executive Fellow.
Dr. Veenema received a Bachelor of Science in Nursing from Columbia University in 1980; and a Master of Science in Nursing Administration in 1992 and Master in Public Health in 1999 from the University of Rochester School of Medicine and Dentistry. In 2001, she earned a PhD in Health Services Research and Policy from the University of Rochester School of Medicine and Dentistry. She is a Nationally Certified Pediatric Nurse Practitioner and worked in the Pediatric Emergency Department at Strong Memorial Hospital in Rochester, New York.
Dr. Veenema has authored many articles on emergency response and disaster preparedness, and on smallpox in particular. She is the author of the textbook Disaster Nursing and Emergency Preparedness for Biological, Chemical and Radiological Terrorism, published in August 2003. This book received the AJN Book of the Year award. Dr. Veenema is Program Director for a 30-credit Masters program entitled "Leadership in Health Care Systems: Disaster Response and Emergency Management", that is currently offered at the University of Rochester. She serves on the Institute of Medicine Review Panel for the Smallpox Vaccination Implementation, is on the editorial board for the journal Disaster Management & Response, the Board of Directors for the International Nursing Coalition for Mass Casualty Education (INCMCE), and has served as an expert reviewer for the New York State Nurses Association and the New York State Department of Health in the development of "Smallpox as a Biological Agent of Terror: Pre-event Information"
Joanna Tõke, MPH
Joanna Tõke, MPH, is a graduate of the Department of Community and Preventive Medicine at the University of Rochester School of Medicine and Dentistry. She received her Bachelor of Science and Bachelor of Arts degrees in Microbiology and German, respectively, also from the University of Rochester. Ms. Tõke is a member of Phi Beta Kappa and three-time All-American in Tennis.
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