National networks that support biological analysis include the LRN and Emergency Laboratory Response Network (eLRN). These networks are composed of clinical hospital and public health laboratories, public and commercially owned environmental laboratories, and federal laboratories such as the CDC and U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID).The LRN is a joint project of the CDC, the Association of Public Health Laboratories, and the FBI, coordinating the response to threats associated with possible bioterror incidents (see Chapter 8). The LRN is designed to improve communication between the more than 140 local, state, and federal laboratories involved in the network nationally. The LRN is organized with a chain of command structure, based on government regulations and select agent control rules, operating under the guidance of the Department of Health and Human Services. Specifically, the LRN has three levels of laboratory association: sentinel, reference, and national. This tiered analytical network provides a referral-based support system of increased proficiency and enhanced capabilities. The most common LRN elements are the sentinel laboratories, including hospitals, clinics, or first-responder networks. These laboratories typically act in the initial attempts at biological characterization, or "rule in/rule out'' analysis. The middle tier comprises the reference laboratories, which provide a higher level of analytical sophistication for agent identification, often confirmatory for earlier sentinel laboratory testing. Reference laboratories typically include state DOH public health laboratories. The top tier of the network encompasses agencies such as the CDC, which are the source for definitive analysis of even the most hazardous of infectious agents. The threat level determines the LRN response, and as many naturally occurring water-borne pathogens are listed as select agents, their testing is regulated by the LRN.
The EPA has established the eLRN from a network of environmental laboratories to provide laboratory assistance during a natural disaster or a chemical, biological, radiological, or nuclear incident. The network focuses on all aspects of the protection of the nation's drinking water supply, including safety guidelines, sampling regulations, and transport documentation. This network is designed to provide laboratory support during an incident in the event that the initial jurisdic-tional laboratory cannot respond or requires additional assistance. An incident involving a select agent has much stricter guidelines than does one involving a natural water-borne pathogen. A laboratory, when responding to an incident may request aid and can receive assistance through either a federal EPA laboratory or state public health laboratory. In the event of an act of biological terrorism, the eLRN laboratories respond and analyze specimens by using validated protocols available through the LRN. Standardized methods are in place to ensure consistency and to avoid interlaboratory variations in reporting. Reporting laboratories are required to adhere to an overall incident response structure that requires emergency (24-hour) availability and strict guidelines for sample handling, covering analysis, custody, and sample disposal. Other similar response networks exist to respond to an attack on the nation's food supply, such as the Food Emergency Response Network (FERN), which has been established jointly by the FDA and the U.S. Department of Agriculture. The FERN has also established a laboratory system that communicates with the LRN network. Although the main focus of this network is the response to food contamination issues, the network is set up to handle water-borne events, and protocols are in place to deal with water testing. Any jurisdictional issues in the case of any hazardous materials incident are resolved under a federal mandate regarding the Incident Command System/Unified Command (ICS/UC) (U.S. Department of Labor, 2005). The ICS is an organizational system adopted by emergency responders throughout the nation, serving as a tool to coordinate efforts and structure the incident response. Any instance of a compromised water system will likely require a coordinated response from multiple agencies. For incidents necessitating cooperation among multiple federal or regulatory agencies, such as those involved in national emergencies, the UC process is further delineated so that each agency retains individual authority and accountability under the coordinated response. As of 2005, the National Incident Management System, as part of the Homeland Security Initiative, requires education and training in the use of the ICS for all incident responses down to the local level.
Broadly, there are two possible situations associated with detection of a select agent that can arise. In the first scenario, is when patients present at local hospitals or physicians' offices. Determination of the cause of illness first depends on the latency between exposure and onset of illness, which can be a matter of days. Because of this large lag time, the laboratory network system is expected to function mainly in identifying the organism responsible for illness, and not as an early warning network. The initial determination of illness could thus be determined in a few days, depending on the virulence and rate of infectivity of the agent, the number of patients presenting symptoms, etc. Any obvious warnings, such as an overwhelming number of patients at a hospital emergency department, will initiate reference and/or national laboratory responses, which in turn will dramatically speed up the identification of the organism.
In the second scenario, a network response would be invoked as the result of a discrete and verified action, such as a called-in threat or a security breach in which a terrorist has actually introduced a contaminant or is judged likely to have done so (it is unlikely that a mere telephone threat or break-in at a facility would, by itself, trigger the network response). In this type of event, the response level is elevated, likely starting with a second-tier reference laboratory, and identification of the threat is rapid, typically within hours. In the absence of a defined outbreak, the standard course of action initiates with field sampling/screening, followed by sentinel laboratory testing and, if required, reference laboratory analysis and/or confirmation. The national laboratories generally are involved when a highly infectious agent is suspected. A tentative positive response to a biological agent at any stage initiates an immediate referral to a higher level of the LRN.
Because of the complexity of testing and the large number of potential water-borne agents, analysis uses a layered procedural methodology. Biological threats are screened in order of likelihood, based on the circumstances of the case and proceeding with a systematic elimination of organisms. For example, the symptoms associated with a smallpox outbreak differ markedly from an anthrax exposure. Because an attack with weaponized anthrax is presumed more likely than an attack using smallpox, unless the symptoms showed otherwise, a test for anthrax would be performed before other rarer select agents. As the presence of certain pathogens is ruled out, sequential testing for the less common pathogens is performed.
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