How Feed Vehicles Impact Disease Transmission: Findings from Recent Research

Written by: Taylor Lekin   |   July 30, 2024

biosecurity, African swine fever, research, swine

Considering the ongoing highly pathogenic avian influenza (HPAI) outbreaks and the looming threat of an African swine fever (ASF) outbreak, biosecurity should be on everyone’s mind. Jason Galvis, Ph.D., a research scholar, and Gustavo Machado, Ph.D., an associate professor at North Carolina State University (NCSU), recently published a study about the role of vehicle movement in swine disease dissemination. I spoke with Machado to discuss their findings and, more importantly, if the feed industry contributes to disease transmission and what we can do to prevent it. 

While their research focuses on the transmission of the porcine epidemic diarrhea virus (PEDv), the findings provide valuable insights into the impact that vehicles, especially those transporting feed, can have on the spread of viruses.

The Research

Machado explained that their research focused on collecting real-world data to inform and develop mathematical models that can replicate what happens in real-world scenarios. The NCSU team collected data on 823 vehicles transporting pigs, feed, and people to over 6,000 farms. They knew the locations of the farms, which allowed them to assess the risks of local transmission and track pig movements to understand how infections might spread through transportation vehicles.

Machado stated:

"The major contributors to the spread of the virus are the pigs themselves. However, we have about 20% of transmissions that can be linked back to other vehicles, including feed vehicles. So, it is not zero, and there is a significant percentage that can be linked back to those vehicles.”

Feed Vehicles

Machado highlighted a prevalent misconception in the agriculture industry: feed vehicles pose less risk because they do not transport live pigs. This overlooks that feed vehicles often travel to the same areas where live pigs are kept, increasing the risk of cross-contamination.

Another critical factor in their model is the effectiveness of cleaning the vehicles that deliver the feed. The researcher explained how the team accounted for this variable:

“It seems that the feed vehicles are not being cleaned as often as other vehicles. In some occasions feed transportation vehicles can visit 20-30 farms without being cleaned, which increases the risk of [virus] spreading.”

Cleaning Protocols

One challenge lies in ensuring that the disinfection process effectively reduces or eliminates the viral load, he explained. The inconsistent and inadequate cleaning of feed vehicles poses a significant biosecurity risk. Recognizing this critical need for better cleaning protocols, Machado emphasized the importance of enhancing current practices:

“We are currently working on a project to swab vehicles at the cleaning stations to understand where we are with cleaning efficacy. It seems that we are closer to 0% than 100% in eliminating virus particles. We see a lot of contaminated vehicles being cleaned and remaining contaminated, so it’s time to work on and improve our cleaning protocols. While this is significant, the question that remains is if the positive samples contain live virus capable of infecting pigs.”

Preventing the Spread

This research on disease transmission among swine farms underscores the complexity of biosecurity challenges. Looking ahead, Machado offered the following insights and recommendations for the feed industry:

1. Understanding Vehicle Risk: Utilizing GPS technology to increase traceability among transportation vehicles can provide a clearer picture of the risk of disease spread and help refine prevention strategies. The research team is currently aiming for a national-level study that can support this effort.
2. Increased Cleaning Frequency: Current practices of cleaning feed vehicles are inadequate. It is important to find effective and practical cleaning protocols and ensure vehicles are being cleaned regularly to reduce the risk of viral transmission.
3. Rerouting Vehicles: The concept of rerouting vehicles based on infection status is a promising approach to reducing disease spread. By avoiding the movement of potentially contaminated vehicles to uninfected farms, the risk of transmission could be minimized.
4. Developing Biosecurity Plans for Feed Mills: Utilizing biosecurity plans for feed mills, like the secure poultry or pig supply plans, can create a cleaner environment and reduce contamination risks. Biosecurity is an essential and ongoing part of disease risk mitigation in both feed mills and live production, and the feed industry should remain vigilant.

He said:

“If you do these things together, we should be able to isolate the risk of spreading quite a bit. This is where we should be moving if we want to mitigate the risk of transmission.”

Learn more about Machado's ongoing research projects here.

As a reminder to members, the American Feed Industry Association’s biosecurity guide, “Developing Biosecurity Practices for Feed Ingredient Manufacturing,” can serve as a great resource for developing or improving current biosecurity practices. Read other blog posts about African swine fever or biosecurity.