Larson R L
College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA.
Theriogenology. 2008 Aug;70(3):565-8. doi: 10.1016/j.theriogenology.2008.04.011. Epub 2008 May 23.
It is important for food animal veterinarians to understand the interaction among animals, pathogens, and the environment, in order to implement herd-specific biosecurity plans. Animal factors such as the number of immunologically protected individuals influence the number of individuals that a potential pathogen is able to infect, as well as the speed of spread through a population. Pathogens differ in their virulence and contagiousness. In addition, pathogens have various methods of transmission that impact how they interact with a host population. A cattle population's environment includes its housing type, animal density, air quality, and exposure to mud or dust and other health antagonists such as parasites and stress; these environmental factors influence the innate immunity of a herd by their impact on immunosuppression. In addition, a herd's environment also dictates the "animal flow" or contact and mixing patterns of potentially infectious and susceptible animals. Biosecurity is the attempt to keep infectious agents away from a herd, state, or country, and to control the spread of infectious agents within a herd. Infectious agents (bacteria, viruses, or parasites) alone are seldom able to cause disease in cattle without contributing factors from other infectious agents and/or the cattle's environment. Therefore to develop biosecurity plans for infectious disease in cattle, veterinarians must consider the pathogen, as well as environmental and animal factors.
对于食用动物兽医来说，了解动物、病原体和环境之间的相互作用非常重要，以便实施针对特定畜群的生物安全计划。免疫保护个体数量等动物因素会影响潜在病原体能够感染的个体数量，以及在群体中的传播速度。病原体的毒力和传染性各不相同。此外，病原体有多种传播方式，这会影响它们与宿主群体的相互作用方式。牛群的环境包括其饲养类型、动物密度、空气质量、接触泥浆或灰尘以及其他健康拮抗因素（如寄生虫和应激）；这些环境因素通过对免疫抑制的影响来影响畜群的先天免疫力。此外，畜群的环境还决定了潜在感染动物和易感动物的“动物流动”或接触与混合模式。生物安全是指试图使传染源远离畜群、州或国家，并控制传染源在畜群内的传播。仅传染源（细菌、病毒或寄生虫）在没有其他传染源和/或牛群环境的促成因素的情况下，很少能够在牛群中引发疾病。因此，为制定牛传染病的生物安全计划，兽医必须考虑病原体以及环境和动物因素。
