Date of Award
Master of Science
Veterinary Diagnostic and Production Animal Medicine
Veterinary Preventative Medicine
Derald J Holtkamp
Biosecurity is an important tool to prevent the likelihood of a disease outbreak in swine farms that can have high economic consequences for the farm. There has been a focus on the decontamination of small and large supplies entered into swine herds and on decontamination protocols for livestock trailers, since both of these events have been well documented as potential risks for disease outbreaks in herds. Currently, in the industry, there is a large variation on how supplies are decontaminated when entered onto farms and how livestock trailers are handled aftermarket loadout events. These biosecurity protocols are always evolving as more research is being performed in these fields to properly identify appropriate applications and limitations of these protocols. There is very little information on UVC doses for Senecavirus A (SVA) disinfection on surfaces; however, there is a moderate amount of literature on UVC doses for other picornaviruses, such as various enteroviruses and hepatitis A virus (HAV) inactivation in water. Doses from 100-120 mJ/cm2 should be sufficient to obtain a 4 to 5 log reduction of most viruses in the family Picornavirdae in most liquid mediums, with the exception of HAV. It is difficult to directly apply information from UVC water disinfection to UVC surface or air disinfection (Kowalski, 2009), but it can serve as a starting point to help guide UVC doses for picornaviruses, such as SVA, disinfection on surfaces. Fifty peer-reviewed research articles were identified in the literature available on UVC disinfection on many different types of surfaces, including fruit, vegetable and meat surfaces, non-permeable materials such as plastic, stainless steel and aluminum, and permeable surfaces such as cotton and polycotton materials, wood, and carpet, encompassing a large variety of bacterial and viral pathogens. A majority of these studies suggest that as surfaces become more rough, uneven, or permeable, UVC efficacy is decreased to some extent. Furthermore, human medicine and the food industry have done research looking at UVC efficacy in the presence of organic material. UVC efficacy in the face of organic material varies depending on the type of organic material used (feces vs. fetal bovine serum) and load (small amount vs. large amount). In general, the more organic material present on a small surface area, the lower the UVC efficacy against a wide variety of bacteria and viruses. Also, RH and temperature are conditions to take into account when utilizing UVC. Although effects of humidity may be pathogen-specific for viral agents, in general, bacteria may experience a decrease in UV susceptibility at higher RH. To directly investigate the efficacy of UVC on SVA on different surface types, original research was conducted to evaluate SVA inactivation due to UVC exposure on plastic, cardboard, or cloth, in the presence of organic material, and subjected to shadowing from grated metal shelves. A commercially available UVC PTC with a 5-minute exposure time and a simulated SER for a 120-minute exposure time was utilized. In this study, UVC inactivation resulted in over a 7-log reduction on plastic, with no organic material present, in the PTC and SER. A second review was done to summarize biosecurity interventions commonly utilized in the swine industry on livestock trailers to prevent transmission to swine herds. It is well documented that livestock trailers serve as a source of transmission for pathogens such as PEDV and PRRSV (Lowe et al., 2014; Dee et al. 2013). Millions of swine are moved across the United States every day, either to other production sites, cull markets, or packing plants, posing a risk for contamination of livestock trailers and the various collection points or barns they are being loaded into. A majority of the studies available focus on a combination of washing, disinfection, and TADD. Washing, disinfecting and drying or utilizing a TADD system together accomplish decontamination better than when any one method is used alone. There is a need for protocols to add additional layers of biosecurity to events such as marketing swine to reduce the likelihood of contamination spread from livestock trailer to herds, in the case that the livestock trailer is not washed, disinfected and dried correctly or not washed at all. Protocols such as removing organic material from packing plants could also be a potential biosecurity layer added to reduce the likelihood of disease transmission. To directly investigate a protocol that would add an additional layer of biosecurity, original research was conducted to evaluate the use of a staged loading protocol during market loadout to decrease contamination from livestock trailer to the barn. Under the conditions of the study, the staged loading procedure effectively reduced the transfer of Glo Germ, used as an indicator for bacterial pathogens, from livestock trailers to barn, but did not completely eliminate it. The first study and review suggest that UVC can be a practical application for the decontamination of small supply entry on swine farms when utilized correctly. When utilizing UVC for small supply entry, only non-permeable surfaces such as plastic should be decontaminated. They should be free of any organic material and proper maintenance of UVC chambers, such as changing UVC bulbs regularly and cleaning dust out of chambers, should be performed. The second study and review suggest that additional layers of biosecurity, such as staged loading during marketing events, can help reduce the likelihood of contamination transfer from livestock trailer to the barn.
Chelsea R Ruston
Ruston, Chelsea R., "The use of ultraviolet-C light to decontaminate materials frequently brought onto swine farms and a staged loading procedure to reduce frequency of contamination from livestock trailer to barn" (2020). Graduate Theses and Dissertations. 18395.