Why do pathogens continue to outwit the sophisticated biosecurity systems put in place by the pork industry?

It's partly because the industry doesn't have all the answers about how swine disease organisms spread, says Scott Dee, DVM, University of Minnesota. Plus, over time, humans miss or skip details. Then, when diseases strike, they do retrospective analyses that don't yield concrete results.

And, says Dee, when swine pathogens outwit biosecurity systems, all too often humans quickly jump to the “default explanation” in lieu of scientifically proving what happened. Dee says the classic default explanation for a farm disease outbreak is aerosol transmission.

“There is little scientific evidence of aerosol transmission of swine pathogens, and absolutely no proof of its occurrence in the field,” he stresses.

Instead of relying on the default mechanism, scientists need to use epidemiological surveys and questionnaires that have been updated to include questions regarding new research information. Researchers also need to investigate routes of transmission using designs that involve multiple replications.

In short, researchers and swine practitioners need to constantly challenge and rethink biosecurity protocols, emphasizes Dee. Too much money is being spent and too much failure is occurring.

Dee suggests rewriting the biosecurity rules based on what we now know. He offers these seven checkpoints:

1. Introduction of genetic material: Establish a closed herd policy for genetic improvement to minimize animal entry. Quarantine and test all great-grandparent breeding stock using a statistically valid, random sampling protocol.

2. Personnel entry: Eliminate all downtime that exceeds 12 hours. Require the use of plastic footwear prior to entering office areas in hog barns. Require all footwear to be placed on elevated shelving or perforated plastic flooring to prevent pooling of debris and liquid from soles of boots or shoes.

   Personnel should shower in and out of units using standard operating procedures. Eliminate “pass-through” windows. Wear gloves at all times in animal areas.

3. Container entry: Establish a neutral, off-farm point for all containers and shipping parcels. All sides of these items should be quarantined for at least 12 hours, disinfected with Lysol spray and allowed to air dry prior to entry into the farm.

4. Insects: Install insect screen on sidewall openings of naturally ventilated barns and build only mechanically ventilated facilities in the future. Remove any hitchhiking insects from vehicle cabs before visiting farms.

5. Vehicles: Invest in a truck wash facility that can be properly managed. Use disposable plastic boots when washing vehicles. Clean interiors of vehicles, disinfect cab interiors and floor mats with Lysol spray and allow floor mats to have sufficient drying time.

6. Rodent control: Hire a professional exterminator to visit the farm on a monthly basis.

7. Cross your fingers and pray!