A comprehensive biosecurity program should represent a hierarchy of conceptual, structural, and procedural components directed at preventing infectious disease transmission within and across farms, companies, facilities, regions, countries, and continents. Avoidance or segregation is the most effective way to prevent disease transmission involved with animal ownership or production. But given that all movement of animals within or across groups/borders involves risk of contact, biosecurity measures are needed to reduce unavoidable risk.
Conceptual biosecurity, the primary level of biosecurity, revolves around the location of animal facilities and their various components. The most effective way to limit risk is physical isolation, making this a primary consideration when siting new confinement facilities or farms. Ideally, facilities/farms should not be located in close proximity to other farms or public roads, especially when the area has a high density of animal facilities (although this is not always possible), or next to slaughterhouses, live-animal markets, agricultural fairs, or animal exhibits. Similar isolation methods include limiting the use of common vehicles and facilities; limiting access by personnel not directly involved with the operation; and controlling the spread of disease by vermin, wild animals, and wind.
Structural biosecurity, the secondary level of biosecurity, deals with physical factors, such as farm layout, perimeter fencing, drainage, number/location of changing rooms, presence of showers, air filtration systems, enclosed load-outs, and housing design in general. Long-range planning and programming is important and should consider on-site movement of vehicles, equipment, and animals; traffic patterns; and feed delivery/storage.
Procedural biosecurity, the tertiary level of biosecurity, deals with routine procedures to prevent introduction (bioexclusion) and spread (biocontainment) of infection within a facility. Such processes and activities should be constantly reviewed as part of a disease control program and quickly adjusted in response to disease emergencies; examples include taking a shower or changing footwear and personal clothes with farm-dedicated clothes before entry into the farm, washing hands, and disinfecting equipment at the point of entry.