Researchers use various methods in high-containment laboratories to inactivate pathogens, as shown in figure 1, which they select depending on the type of pathogen to be inactivated and intended use of the inactivated material. Once a method is selected, researchers develop a protocol that outlines a detailed plan for the scientific procedure. The frequency with which inactivation is performed in high-containment laboratories varies significantly, with some researchers conducting inactivation on a daily or weekly basis and others conducting inactivation only a few times each year. Pathogens can be inactivated using physical, irradiation, and chemical methods, each having advantages and disadvantages. For example, inactivating pathogens using heat—a physical method—is generally simple and inexpensive, but may destroy the pathogen’s protein structure, thus rendering the pathogen useless for certain research purposes. Inactivating pathogens using irradiation better maintains pathogens’ protein structure, but irradiators are costly for most laboratories and subject to additional regulations and security concerns. See table 1 for descriptions of selected types of inactivation methods and their advantages and disadvantages. Following inactivation, researchers may test the viability of the material to ensure the pathogen was rendered nonviable. Different methods exist to test the viability of a pathogen, depending on the conditions under which the pathogen grows. For example, viability may be tested by attempting to grow inactivated material on cultured cells or by exposing animals to inactivated material to see if they become infected. Key Terms Related to Pathogen Inactivation Decontamination: the removal or count reduction of contaminating pathogens present on an object. Disinfection: the elimination of nearly all known pathogens but not necessarily all microbial forms, e.g., spores on inanimate objects. High-containment laboratory: biosafety level (BSL)-3 or 4 facilities in which studies are conducted on a variety of dangerous pathogens and toxins. Inactivation: a process to render infectious material (e.g., pathogens) unable to cause disease, but retain characteristics of interest for future use. Irradiation: exposure to radiation (e.g., ultraviolet light, gamma rays, X-rays). Kill curve: the results of a dose-response experiment where a pathogen is subjected to increasing amounts of the inactivating agent to determine the minimum conditions required to render it nonviable or noninfectious. Nonviable: a pathogen that is no longer capable of growing, replicating, infecting, or causing disease. Protocol: a detailed plan for a scientific procedure. Select agent: in the United States, biological select agents (e.g., bacteria, viruses) and toxins have the potential to pose a severe threat to public, animal, or plant health, or to animal or plant products. Validation: for the purpose of inactivation methods, the method must be scientifically sound and produce consistent results each time it is used such that the expected result can be ensured. Methods of validation may include (1) use of the exact conditions of a commonly accepted method that has been validated, (2) a published method with adherence to the exact published conditions, or (3) for in-house methods, validation testing should include the specific conditions used and appropriate controls (from the Select Agent Program). Congress passed the Public Health Security and Bioterrorism Preparedness and Response Act of 2002 to improve the ability of the United States to prevent, prepare for, and respond to bioterrorism and other public health emergencies. This act was one of several acts passed in reaction to the September 11, 2001, terrorist attacks and subsequent anthrax incidents to combat terrorism and address increasing concerns about biological security. It expanded HHS’s authority to regulate select agents to include oversight of all laboratories that possess, use, and transfer select agents affecting public health and safety, and granted comparable authority to USDA for select agents posing a threat to plant or animal health, or animal or plant products. CDC’s Division of Select Agents and Toxins is responsible for the oversight and regulation of select agents that could pose a threat to public health and safety, such as the Ebola virus. APHIS’s Agriculture Select Agent Services is responsible for the oversight and regulation of select agents that could pose a threat to animal or plant health or animal or plant products, such as the virus that causes foot-and-mouth disease. Some select agents, such as Bacillus anthracis, are regulated by both agencies because they pose a threat to both human and animal health. In overseeing the Select Agent Program, CDC’s Division of Select Agents and Toxins and APHIS’s Agriculture Select Agent Services are responsible for ensuring that high-containment laboratories that work with select agents comply with requirements of the select agent regulations. They do this by inspecting laboratories that are registered with the Select Agent Program, ensuring that individuals who work with these agents undergo a security risk assessment, and investigating and enforcing any incidents in which noncompliance with the regulations may have occurred, among other responsibilities. As of May 31, 2016, a total of 286 entities were registered with the Select Agent Program. The Select Agent Program maintains a list of select agents and toxins that they are required to review and republish at least biennially. NIH publishes guidelines detailing safety practices for research involving recombinant pathogens. Compliance with the NIH guidelines is a condition of accepting funding awards from NIH for research involving recombinant material. As part of these guidelines, laboratories receiving funding must report any incidents involving recombinant pathogens to NIH. NIH has issued an incident reporting template that may be used to report these incidents. The Biosafety in Microbiological and Biomedical Laboratories (BMBL) manual, although not prescriptive, is a widely-accepted source of guidance for all research involving pathogens, regardless of whether they are select agents or recombinant pathogens. The manual outlines the principles and practices of biological safety and security and is published in partnership by CDC and NIH. It applies to all biological safety levels of microbiological laboratories, including high-containment laboratories. According to the BMBL manual, biological safety practices are intended to reduce or eliminate exposure of individuals and the environment to potentially dangerous pathogens, and biological security practices are intended to prevent the loss, theft, or misuse of dangerous pathogens and research-related information by limiting access to facilities, research materials, and information. The total number of incidents involving incomplete inactivation that occurred from 2003 through 2015 is unknown for several reasons, including the inability to easily identify such incidents in existing databases. For those that are known, incidents occurred at federal, academic, and private high-containment laboratories and involved a range of inactivation methods and pathogens. The total number of incidents involving incomplete inactivation that occurred from 2003 through 2015 is unknown for three reasons: (1) the inability to easily identify incidents involving incomplete inactivation within incident databases, (2) the absence of reporting requirements for pathogens that are not select agents or recombinant pathogens, and (3) the absence of a clear, consistent definition of inactivation. First, the Select Agent Program and NIH do not have the ability to easily identify incidents involving incomplete inactivation because their incident reporting forms are not structured to specifically identify this type of incident. As a result, neither the Select Agent Program nor NIH (for the oversight of recombinant pathogens) was able to provide us with an accurate number of all incidents involving incomplete inactivation that occurred from 2003 through 2015. Specifically, registered entities are required by federal regulation to report any incidents of theft, loss, or release of select agents to the Select Agent Program, where “release” refers to any instance where pathogens are outside of primary containment, such as an accidental spill of viable pathogens or an incident that results in medical surveillance following an exposure, including those resulting from incomplete inactivation. The Select Agent Program is required to annually report to Congress only on the number and type (e.g., “theft” or “release”) of all incidents that have occurred involving select agents. Select Agent Program officials initially told us that there were 10 incidents involving incomplete inactivation reported to the program from 2003 through 2015 (see table 2). NIH officials initially told us that they were unaware of any incidents involving incomplete inactivation involving recombinant pathogens that had occurred in that time frame. However, upon review of the Select Agent Program’s database of reported incidents, we identified another 11 incidents that involved incomplete inactivation from 2003 through 2015, which we confirmed with the Select Agent Program, in addition to the original list of 10 they provided to us (see table 3). According to officials, the Select Agent Program is not required to specifically report the number of incidents involving incomplete inactivation, as a subset of incidents of theft, loss, or release, to any outside entity. Therefore, identifying this subset of incidents in the database was difficult because reporting forms used to track the theft, loss, and release of select agents are not structured to specifically indicate whether an incident involved incomplete inactivation, nor require laboratories to include “incomplete inactivation” in the description of the incident. As a result, officials cannot easily search their databases to identify such incidents once the information on the reporting forms is entered into the database. According to Select Agent Program officials, the current structure of the reporting forms could affect their understanding of the magnitude of the problem, and a more extensive analysis of the full report descriptions for all incidents in the database could identify additional incidents involving incomplete inactivation. According to the Centers for Disease Control and Prevention (CDC), the equine encephalitis viruses are mosquito-transmitted diseases that can cause severe inflammation of the brain (encephalitis) in horses and humans. Eastern equine encephalitis (EEE) most commonly occurs in the eastern United States and Canada while Venezuelan equine encephalitis (VEE) most commonly occurs in South and Central America but has spread to the United States. Although a rarely seen illness in humans, approximately 33 percent of individuals with EEE die from the disease and many survivors are left with significant brain damage; infected horses have variable death rates as high as 90 percent.