BOX 2-3
Definitions of Level 3 Biocontainment Facilities in the Animal Health Framework

Animal Biosafety Level 3 (ABSL-3): Involves practices suitable for work with animals infected with indigenous or exotic BSL-3 agents that present the potential of aerosol transmission and of causing serious or potentially lethal disease. ABSL-3 builds upon the standard practices, procedures, containment equipment, and facility requirements of ABSL-2.

Biosafety Level 3 (BSL-3): Used with agents that may be indigenous or exotic to the United States that can be contracted by the respiratory route and may cause serious or lethal diseases to humans or animals or cause moderate economic loss to the animal industries. The BSL-3 facility is designed to support research activities with serious or potentially lethal biohazardous materials or infectious substances.

Biosafety Level 3 Agriculture (BSL-3Ag): Designation for animal facilities in which research involves BSL-3 biological agents that present a risk of causing great economic harm should they infect the indigenous animal population (e.g., foot-and-mouth disease). Using the containment features of the standard BSL-3 facility as a starting point, BSL-3Ag facilities are specifically designed to protect the environment by including almost all of the features ordinarily used for BSL-4 facilities as enhancements. All BSL-3Ag containment spaces must be designed, constructed, and certified as primary containment barriers. Colloquially, they may be referred to as ABSL-3 Ag.

SOURCE: Biosafety in Microbiological and Biomedical Laboratories, 4th edition. Available at


Deterrence and prevention of animal disease in the United States involve global strategies that are directed at reducing a potential threat before it reaches the U.S. borders and a border strategy that focuses on interdicting a threat agent at U.S. ports of entry (NRC, 2003a). An overview of international organizations involved in prevention, detection, and diagnosis is provided earlier in this chapter, so the discussion below focuses on components of the framework responsible for interdicting threat agents at U.S. ports as well as during the sale and transport of animals (particularly exotic animals) once they have entered the country.

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