Biosecurity procedures are the first line of defense when protecting your swine herd from transmission of several diseases, including respiratory viruses such as porcine respiratory and reproductive syndrome (PRRS) and swine influenza (SIV).
Transport vehicles pose a risk in disease transmission on farms. It is essential that swine producers consistently apply effective measures to clean, disinfect and dry vehicles used to transport pigs — including trucks and trailers returning from processing plants, other farms and buying stations.
Here are some steps to take:
Clean or wash away visible organic materials. Because PRRS and other viruses can be spread by fecal matter and other body fluids from infected pigs, any organic matter on the trailer or cab has potential to spread virus. The first step in the line of defense is to scrape or shovel soiled bedding to remove manure thoroughly, then wash your truck and trailer until all visible organic materials are removed.
This should be done a safe distance away from your swine barns (or outdoor pens) to minimize exposure of your pigs to dust or fomites and splashed or aerosolized organic matter from the truck. Recommendations for locating and constructing or equipping a low-cost truck cleaning and disinfection station on swine facilities can be found at Secure Pork and Iowa Agriculture.
When power-washing your trailer, use a detergent to help remove all visible organic matter such as animal hair and manure on the trailer. Detergents both aid the process of organic removal and initiate the destruction of pathogens such as viruses, bacteria and parasites. Using cleaning agents that include an acidic solvent will help remove a biofilm layer that can form on surfaces — a layer typically not seen by the human eye but capable of harboring (and protecting) high levels of pathogens.
Use a consistent, systematic approach in the cleaning process. Be sure to wash the outside of the truck. Work from the roof downward along the side panels, and finally the wheels or tires and undercarriage. When cleaning inside the trailer, work front to back, beginning with the ceiling then downward along walls and then the floor.
Any movable gates or ramps should be examined carefully after washing to ensure the entire area has been washed. A final rinse should be given to the entire truck and trailer to confirm that all visible organic matter has been removed.
Disinfect to kill pathogens. When choosing a disinfectant, select one that has been established as effective against the most important pathogens that infect pigs — including PRRS, SIV, PCV2 and PEDV — as well as foreign animal diseases such as African swine fever.
Many of the commercial disinfectants used in swine barns and containment facilities are also effective when used to disinfect trucks. Commercial products shown to be effective against PRRS include Intervention, Virkon S and Synergize. These products are also included on a list compiled late in 2021 of USDA-approved products shown to be effective against ASF.
Many of these products can be safely and effectively applied using a hydrofoamer, which allows for increased contact time and more thorough disinfection of the truck. Your veterinarian is the best source of information regarding disinfectants that are most effective against pathogens that may be especially important in your region.
When using a disinfectant, follow all manufacturer’s safety recommendations, including using protective gloves and eye or face protection. Use these products only in a well-ventilated area and wash hands thoroughly after handling.
When using an ammonia-containing or acidic detergent during the cleaning process, avoid following it with a chlorinated disinfectant, as a reaction may occur that can irritate membranes and cause breathing problems.
Drying the trailer greatly increases the effectiveness of disinfection. Most viruses and other pathogens that infect animals do not survive long under hot, dry conditions. Remove moisture through proper drainage and thorough drying of the trailer.
Drying is best achieved using forced heated air, or baking, to help raise the temperature of the trailer interior and further destroy viruses. A recent study from Jill van Kessel, et al., titled, “Time and temperature requirements for heat inactivation of pathogens to be applied to swine transport trailers,” shows that heating the trailer interior to 167 degrees F for 15 minutes effectively destroys key viruses and bacteria that infect pigs. While baking facilities for livestock trucks are not always available, producers can use industrial shop or space heaters to adequately heat the inside of the trailer.
While less effective and more time-consuming than baking, allowing the trailer to completely dry following disinfection is also an effective practice, according to “Modeling contamination of trucks used in the shipment of pigs infected with porcine reproductive and respiratory syndrome virus” from Krishna Thakur, et al.
Raising the front end of the trailer (achievable by parking on a gradual slope), so that water runs out the back, and allowing airflow throughout the trailer are both useful practices to reduce drying time.
Cleaning the cab and accessories is essential. Another important step in the truck cleaning and disinfection process is to include the cab, floor mats and floorboards. In addition, all equipment such as sorting boards and rattle paddles should be washed, disinfected and dried.
Drivers should wash their hands or apply hand sanitizer, and remove and properly dispose of plastic booties before entering the cleaned cab of their truck.
Use quality control for cleaning and disinfection processes. Remember that surfaces and crevices that appear spotless to your naked eye may harbor biofilm-contaminated areas containing enough pathogens to cause disease on your farm.
The effectiveness of your cleaning and disinfection procedures should be monitored regularly. Including a quantitative assessment step such as collecting swabs for PCR testing or contact plates for sterile replicate organism detection and counting (RODAC) can provide a useful readout, i.e., number of viable microorganisms remaining on the surface following the cleaning and disinfection process.
These assays typically require about two days to fully process at a veterinarian’s office or commercial laboratory. They would be useful, if conducted periodically, for monitoring the effectiveness of your operation’s cleaning and disinfection practices over time, but not practical for making immediate pass-reject decisions for a truck entering your farm.
A faster and lower-cost alternative to swabbing, which could be done routinely on every truck, should include careful, systematic visual inspection of trailer surfaces, paying special attention to corners, hinges, gates and other hard-to-clean locations. This type of trailer cleanliness audit might include relevant metrics such as free of all observable organic matter, and completely dry, and include defined locations (walls, ceiling, floor, gates, hinges) within the trailer, as well as handling equipment.
It is important to monitor the outcome of cleaning and disinfection procedures consistently, including not just how the trucks appear, but also any evidence that diseases are moving between facilities served by the vehicles.
Pig flow considerations can also help mitigate disease risks. The benefits of applying sound cleaning and disinfection procedures can be further enhanced, especially when moving pigs between farm facilities, by careful planning that considers the sequence by which pigs are moved.
Just as you conduct daily pen inspections by moving from high-health to low-health barns or pens to minimize spread of disease, you should proceed from highest health risk and cleanest condition facilities to lower health risk and less clean condition facilities when moving animals.
As losses due to mortality and morbidity associated with a virus such as PRRS can be costly and the diseases difficult to treat, consistent application of sound biosecurity practices — including cleaning and disinfection procedures for trucks hauling livestock onto your farm — are important tools for mitigating the risk of the disease entering your herd. Your farm veterinarian can help with diagnostic procedures and is usually the best source for advice for implementing an effective cleaning and disinfection strategy for vehicles entering your farm facilities.
Thompson, Ferry and Benjamin are MSU Extension pork educators and specialists. Their contact information, along with other pork experts, can be found at canr.msu.edu/pork/experts.