The  practical application of biosecurity begins with science‑based biosecurity principles coupled with effective communication and education, says Mark Engle, DVM, director of Swine Health Programs for the National Pork Board.

Engle participated last spring in a special “Skills and Tools for Practitioners” seminar at the American Association of Swine Veterinarians Annual Meeting in Des Moines, Iowa. He specifically addressed the subject of the practical application of biosecurity.

“Biosecurity plans should be farm‑specific and be living documents to allow for changes as  knowledge increases,” he says. “Many unanswered questions concerning transmission of certain pathogens still exist.”

Engle cites porcine reproductive and respiratory syndrome (PRRS) virus as a disease agent that has caused the swine veterinary profession and the pork production industry “to rethink infectious agent transmission pathways and traditional biosecurity measures.”

Biosecurity programs have traditionally focused on minimizing the “portal of entry” into a population of animals, according to Engle. “Until the emergence of PRRS virus, these traditional methods were quite effective in preventing the introduction of other swine pathogens. PRRS virus continues to defy traditional biosecurity practices and accomplish area spread to the frustration of both veterinary practitioners and producers.

“Although many traditional biosecurity practices are scientifically sound and effective, PRRS virus has caused the industry to consider unconventional means of virus spread. Regional biosecurity and pathogen elimination programs are now being considered with a focus on the ‘reservoirs’ and the ‘portals of exit’ for infectious agents as well.”

Biosecurity plans
You obviously cannot cover every possible biosecurity scenario, but by having a written biosecurity plan for every farm or production system, you can include the basic principles and provide for a foundation for future discussions, says Engle.

“Company veterinarians or consultants should develop these plans to be living documents that can be readily modified as new knowledge becomes available,” he emphasizes.

“In my opinion, the single most important aspect of any biosecurity plan is the level at which the farm staff takes ownership of the plan,” says Engle. “By contributing to the program, staff will take responsibility for its implementation and develop a ‘think on your feet’ mentality to address those unforeseen biosecurity scenarios that cannot be committed to paper.”

In a single farm, entire farm staff contribution to a biosecurity plan is fairly straight forward, but in a production system, a biosecurity committee may be needed. “This committee should represent all facets of the production system with the company veterinarian or consultant serving in an advisory capacity to answer questions and provide educational materials,” Engle says.

Members of the committee should be involved in regular meetings and be committed to bringing comments and ideas to the biosecurity planning process from other employees in the system. “Through this process, farm staff and management provide continuous communication and education, thereby increasing the awareness of the importance of biosecurity procedures,” says Engle. “Education and responsibility are the keys to employee ownership.”

In contrast, says Engle, negative incentives or penalties to deter poor behavior can be costly and counterproductive. “Negative incentives create the impetus for employees to not report
biosecurity breeches for fear of the repercussions. Biosecurity is one of the few areas where penalties for noncompliance can create the opportunity for tremendous losses due to nondisclosure of the breech. To allow for a proper response by management, employees must be encouraged to provide full disclosure of any possible breech in biosecurity whether they are at fault or not.”

8 biosecurity risks
Engle outlines the following eight biosecurity risks that have been identified in today’s pork industry and provides suggestions for helping your clients reduce these risks:

1 Replacement stock. The introduction of infected replacement stock is one of the greatest risks of introducing pathogens into a herd. The need for quarantine of replacements in a biosecured isolation facility prior to entry into a herd is widely recognized. During quarantine, communications with the source-herd veterinarian, coupled with proper testing procedures, will help ensure freedom from known pathogens.

2. Semen. Artificial insemination using fresh semen from an external boar stud has become common in commercial pig production. Semen suppliers should have health assurance programs in place including active communications with the source herds, appropriate biosecurity protocols, and routine health monitoring.

Fresh semen provides a constant risk for rapid dissemination of pathogens through breeding herds if infected semen goes undetected. Many semen suppliers have implemented testing procedures for PRRS virus on every collection to avoid unknowingly delivering infected semen downstream.

In addition, health monitoring of boar studs should include daily monitoring of clinical signs since reliance solely on diagnostic testing will only detect known diseases. Both the American Association of Swine Veterinarians and the National Pork Board have documents available describing health standards and health assurance procedures for semen suppliers.

Handling procedures for delivery and acceptance of semen containers also need to be considered. The ability to introduce PRRS virus via containers has been demonstrated.

3. Transportation. Transportation has long been considered a high biosecurity risk due to the frequency of pig movements, as well as the difficulty in proper cleaning and disinfecting of trailers, particularly in certain climates.

Pathogen transmission can occur through an improperly sanitized trailer or due to exposure to another source during transit. It has been demonstrated that proper drying of trailers is an important component of transportation biosecurity to prevent PRRS virus transmission. Drying has been recognized as an important procedure in the sanitation of transport vehicles. Recently, “trailer baking” has been applied in certain production systems.

The National Pork Board’s Trucker Quality Assurance  (TQA) program provides biosecurity education to truckers. Swine veterinarians should consider working closely with the commercial trucking firms in their area to provide continued education and reinforce transportation biosecurity principles.

4. People. People are a higher risk as a mechanical vector than a biological vector for pathogen transmission to swineherds.

The one exception may be swine influenza virus (SIV). Extended downtime for people has been established in the past without a scientific basis. These extended downtimes have added unnecessary costs and inefficient use of personnel.

Research has shown that a change of outer garments and washing hands and arms is adequate to prevent transmission of a variety of pathogens. 

At a biosecurity workshop during last year’s University of Minnesota Allen D. Leman Swine Conference, breakout groups decided the most common-sense downtime between commercial production systems should be overnight. An overnight downtime should ensure a shower and change of clothes.

Vehicles should be washed routinely including cleaning of interiors and disinfection of floor mats. In addition, farm staff should be concerned when new, unfamiliar delivery or service personnel arrive on the farm. For security purposes, companies servicing pork producers should notify producers when dispatching new personnel to the farm.

Prior to allowing entry into the farm, staff should confirm that the person is a legitimate employee of the service provider. If so, farm staff should then determine if the employee has had proper biosecurity training.

5. Supplies. Handling procedures for delivery and acceptance of supplies and containers should be given some consideration. Some farms have established delivery rooms to allow for “delivery downtime” and possible disinfection or fumigation before entry into the animal space.

6. Rodents, flies, mosquitoes. Proper building maintenance, rodenticide usage and vegetation control on the farm site are commonly practiced and can effectively control rodents.

Mechanical transmission of PRRS virus by flies and mosquitoes has been confirmed in recent scientific research studies. As a result some swine veterinarians and their clients are considering installing fly screen on naturally ventilated buildings as well as on air inlets in mechanically ventilated buildings. The negative pressure created inside mechanically ventilated buildings is an
insect deterrent in itself. The fly screen itself will restrict air movement as well as the obvious need for continual cleaning to prevent further restriction.

Based on the evidence that PRRS virus can remain viable in flies for 12 hours, it would seem logical for transportation, service, and delivery personnel to take precautions against inadvertently transporting flies between farms inside their vehicles.

7. Dead stock removal. The three most common methods of dead stock removal are composting, incineration, and rendering. The risks associated with rendering trucks within a close proximity to the farm are apparent, so dead stock should be taken as far from the farm site as is practical. Composting has become more popular due to cost and the elimination of having a rendering vehicle close to the farm. However, improper composting can attract unwanted wildlife.

8. Aerosol. Aerosol spread of certain infectious agents has been well documented. Existing facilities in pig-dense areas or along major roads may want to consider the possible use of air filters to control aerosol transmission. The practical application of air filters in pig production needs to be further
investigated.  

Pork Checkoff assists with biosecurity focus areas

The National Pork Board’s Biosecurity Guide for Pork Producers (www.porkboard.org)  provides one method to assess biosecurity and to begin to develop farm-specific plans. The areas of focus identified in the guide include:

Isolation biosecurity (direct spread through replacement stock):

  • Facility location
  • Pig flow
  • Personnel
  • Health monitoring and interpretation
  • Acclimation

Indirect spread (area spread):

  • Facility location
  • Access deterrents
  • Pest and wildlife control
  • Feed
  • Transportation
  • Personnel and visitors
  • Semen
  • Cleaning and disinfecting
  • Carcass removal
  • Supply and product deliveries