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Solve biosecurity overload by focusing on the basics

Keeping a hog farm free of pathogens can be a daunting task for producers. The process to evaluate potential risks and then undertake biosecurity measures to manage the risks has become complex. In fact, the complexities of biosecurity are so great that some producers refrain from doing anything.

“The biosecurity recommendations, which typically are in the form of long lists, serve to overwhelm producers who lack the information to prioritize and can’t act on every recommendation at once,” reported Derald Holtkamp, DVM, Iowa State University, in a presentation at the 2017 American Association of Swine Veterinarians conference.¹

“The completely predictable response is to do nothing.”

Holtkamp hopes to clarify the issue of biosecurity and spur producers to take action by going back to the basics of how an infection occurs.

How pathogens enter farms

Swine viral and bacterial pathogens must be introduced to a hog farm by what is called a “carrying agent.” Examples include replacement gilts, semen, livestock trailers, on-farm employees, feed and air.

“A comprehensive list of all carrying agents that enter farms on a regular basis is very long and quickly overwhelming,” Holtkamp said.

“Risk events” describe the necessary activities on a farm that subject the herd to the potential introduction of pathogens. Examples are the delivery of semen, entry of employees and feed delivery.

Holtkamp recommends focusing on risk events first and then looking at the carrying agents involved with the event. The list of potential risk events is much shorter and less overwhelming. Another advantage is the frequency of risk events can be determined. Every time a risk event occurs, the farm is subjected to risk.

Infection occurs

A series of failures and events must occur for a pathogen to be introduced into a herd. First, a carrying agent becomes exposed and infected or contaminated with the pathogen. Then the infection or contamination is not detected and/or mitigated, resulting in an infected or contaminated carrying agent entering the farm during the risk event.

Finally, the pathogen is transmitted from the carrying agent to one or more pigs in the herd.  Each potential failure represents a critical control point.

Figure 1. Series of failures and events required for a pathogen to be introduced into a herd

Figure 1 shows the series of failures and events needed for a herd to be infected by a pathogen. Holtkamp said using strategies to target any critical control point might reduce the probability of a failure or reduce the frequency of the carrying agent entering the farm.

Concepts like these can be tailored to individual herds to identify the greatest risks and biggest gaps in biosecurity instead of relying on general recommendations for all hog farms.

The concepts were developed and used in a pilot outbreak-investigation program for porcine reproductive and respiratory syndrome virus funded by the Iowa Pork Producers Association, Holtkamp added.

¹Holtkamp D, Linhares D. Understanding how pathogens infect pig farms, Biosecurity. 48^th American Association of Swine Veterinarians’ Annual Meeting. 2017;3-4.