Supply entry biosecurity deserves more attention, says Lindsey Britton, a veterinary student in the North Carolina State University College of Veterinary Medicine. Supply entry is a critical area for disease introduction.
One of the common biosecurity practices for supply entry is disinfection via time and temperature. Not only does it require extended periods of time, but it may not be entirely effective, she says, which highlights the need to explore alternative procedures.
Britton recently conducted a study looking at dry fogging systems that offer an alternative disinfection method and have demonstrated efficacy in reducing pathogen viability, including Salmonella spp.
“The system converts a liquid disinfectant into a dry fog of vapor particles less than 10 microns,” Britton said at the Allen D. Leman Swine Conference. “This small particle size enables rapid, thorough diffusion, making it ideal for disinfecting supplies.”
However, limited research exists evaluating the effectiveness of this system against other swine-specific pathogens under shortened durations. Britton set out to evaluate the efficacy of a commercially available Micro-Spray system in inactivating Salmonella spp. and porcine reproductive and respiratory syndrome virus (PRRSV) during supply entry disinfection, under simulated, shortened durations.
Study Set Up
She utilized a supply entry room (11’ x 13’ x 9’) in a depopulated farm for her project. The room contained metal shelving, in which cardboard boxes were randomly dispersed to replicate a typical supply entry event, she explains.
A Micro-Spray system was installed within the center of the room on the ceiling and two different disinfectants were evaluated: hypochlorous acid (Disinfectant A) and hydrogen peroxide with peracetic acid (Disinfectant B). Petri dishes were aseptically plated with either 1 mL of modified-live PRRSV MLV, Salmonella TC vaccine, or PRRSV positive serum. One MLV dish and one Salmonella dish served as positive controls and placed outside of the room.
The remaining plates were placed into the fogging chamber at various locations: in open air on the metal rack, between two cardboard boxes, and under a cardboard box flipped upside down. This procedure was repeated for both disinfectants using three different durations: 10-, 30-, and 60-minutes of contact time post-fogging.
Salmonella plates were later cultured at an accredited veterinary diagnostic lab. The PRRSV MLV and PRRSV serum plates were analyzed with a viability RT- qPCR assay.
Did It Work?
“This pilot evaluation showed that hydrogen peroxide with peroxyacetic acid disinfectant successfully reduced PRRSV viability with a contact time of 30 and 60 minutes and inhibited the culture of Salmonella at all contact times,” Britton says. This study demonstrated that dry fog may be a viable alternative for disinfecting supplies that will be entered into farms and should be evaluated further to determine the best practice for the industry.”
She believes utilizing a Dry Fog system with an appropriate disinfectant could be a viable option for disinfecting supplies and getting them into a farm in a matter of hours rather than days.
“This could be valuable in emergency scenarios, such as when fans break or feedlines need immediate repair, to quickly obtain supplies on the farm with the assurance that they have been disinfected for potential pathogens,” Britton adds.
She was one of seven finalists for the Morrison Swine Innovator Prize recognized during the Allen D. Leman Swine Conference. She presented her research findings during a session at the conference.
Britton says this study should be replicated with other PRRSV strains, supply room designs and disinfectants to better understand dry fog system capabilities.
