Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, Saint Paul, MN, USA.
Vet Microbiol. 2012 Jun 15;157(3-4):304-10. doi: 10.1016/j.vetmic.2012.01.010. Epub 2012 Jan 17.
Porcine reproductive and respiratory syndrome virus (PRRSV) is an economically significant pathogen of pigs that can be transported via the airborne route out to 9.1 km. To reduce this risk, large swine facilities have started to implement systems to filter contaminated incoming air. A proposed means of air filtration failure is the retrograde movement of air (back-drafting) from the external environment into the animal air space through non-filtered points such as idle wall fans; however, this risk has not been validated. Therefore, the purpose of this study was threefold: (1) to prove that PRRSV introduction via retrograde air movement through idle fans is a true risk; (2) to determine the minimum retrograde air velocity necessary to introduce PRRSV to an animal airspace from an external source; and (3) to evaluate the efficacy of different interventions designed to reduce this risk. A retrograde air movement model was used to test a range of velocities and interventions, including a standard plastic shutter, a plastic shutter plus a canvas cover, a nylon air chute, an aluminum shutter plus an air chute and a double shutter system. Results indicated that retrograde air movement is a real risk for PRRSV introduction to a filtered air space; however, it required a velocity of 0.76 m/s. In addition, while all the interventions designed to reduce this risk were superior when compared to a standard plastic shutter, significant differences were detected between treatments.
猪繁殖与呼吸综合征病毒（PRRSV）是一种对猪具有重要经济意义的病原体，可通过空气传播途径传播至 9.1 公里以外的地方。为了降低这种风险，大型养猪场已开始实施过滤污染进气的系统。空气过滤失败的一种潜在方式是外部环境中的空气通过未过滤的点（如闲置的壁扇）逆行进入动物的空气空间，即逆向气流（倒灌）；然而，这种风险尚未得到验证。因此，本研究的目的有三：（1）证明通过闲置风扇的逆向气流传播 PRRSV 是一种真实的风险；（2）确定从外部来源将 PRRSV 引入动物空气空间所需的最小逆向空气速度；（3）评估旨在降低这种风险的不同干预措施的效果。使用逆向空气流动模型测试了一系列速度和干预措施，包括标准塑料百叶窗、带帆布盖的塑料百叶窗、尼龙空气滑梯、带空气滑梯的铝百叶窗和双百叶窗系统。结果表明，逆向空气流动是 PRRSV 引入过滤空气空间的真实风险；然而，它需要 0.76m/s 的速度。此外，尽管所有旨在降低这种风险的干预措施与标准塑料百叶窗相比都具有优势，但在处理之间仍检测到显著差异。
