Take a ready, aim, fire approach to sow farm biosecurityTake a ready, aim, fire approach to sow farm biosecurity
Holtkamp's "hazard tales" illustrate need for sustainable biosecurity practices.
August 16, 2022
Since 2009, the cumulative annual incidence of porcine reproductive and respiratory syndrome outbreaks has been between 20- 40%, according to data gathered from the Morrison Swine Health Monitoring Project. But Derald Holtkamp points out there have been instances over the last 13 years where that percentage was closer to 20%, specifically during the porcine epidemic diarrhea break in 2013/14 and when China broke with African swine fever in 2018/19.
"Basically, we have this sort of cycle going on here. We have a crisis or fear of a crisis, and the industry responds to that, becomes more diligent, focuses on biosecurity for a while, and then that focus on biosecurity seems to work, even though it's not being done necessarily or strictly for PRRS," Holtkamp says. "It has spillover effect, the annual incidence of PRRS outbreaks goes down. But then following that, the vigilance gets replaced by complacency and we have that incidence creep back up again, so progress is not really sustained."
To make more sustainable progress, the Iowa State University professor of swine production medicine says the industry needs to adopt a more systematic approach to identifying biosecurity hazards.
"We need a way to go in and try to identify where the hazards are, where the farms are most vulnerable first, so then we can prioritize where we want to spend our resources," Holtkamp says.
He suggests taking a "ready, aim, fire approach," rather than the "ready, fire, aim" used today. In the context of assessing biosecurity on swine farms, producers should take a "HAACP approach" to identify the most significant hazards for priority.
"A hazard analysis really involves a complete review of all the production events, so things like entry of employees, entry of semen, entry of gilts, all of those are sort of typical production events that happen, and so if we want to understand where the hazards lie in those events, we have to dig into the details," Holtkamp says. "We have to understand the who, what, when, where and how."
A hazard analysis can be done retrospectively – immediately after introduction of a pathogen or following an outbreak investigation, or prospectively – before the introduction of a pathogen to prevent future outbreaks. Holtkamp uses the Pathogen Outbreak Investigation form from Swine Health Information Center to conduct hazard analyses with producers. Using the form helps conduct a more comprehensive and thourough investigation so significant hazards are not missed and in 95% of the investigations he has been involved in, the form had just about every biosecurity breach possible.
He also acknowledges 95% of the investigations he has assisted with happened retrospectively following an outbreak.
"Producers tend to be very attentive at that time. That's the time to really learn best, learn from our mistakes and that's really the purpose of doing them then," Holtkamp says.
Before filling out an investigation form, Holtkamp says it's important to define what a hazard is. When assessing biosecurity in swine farms, it is a circumstance or, action or inaction, that is likely to result in a failure that may lead to the introduction of a pathogen by a pathogen-carrying agent. A pathogen-carrying agent is anything that can carry a virus to a herd, such as pigs, people and vehicles. Three failures must happen for a virus to be introduced into a herd: failure to prevent contamination or infection of a pathogen-carrying agent, failure to mitigate the infection or contamination and failure to prevent transmission from the pathogen-carrying agent to pigs in the herd.
For example, a first failure could happen during the entry of replacement breeding gilts. The livestock trailer, driver and equipment used to move the gilts could all potentially be contaminated, or in the case of the gilts coming on farm, infected. If the truck was responsible for bringing in PRRS, the next question becomes were control measures taken to remove or inactivate the virus? If not, that would be the second failure.
"So maybe we have a truck wash, trailers look washed and disinfected, dried maybe even between every load, but we've never gone out there and even asked them if they're following the protocols we set out at the beginning," Holtkamp says. "That's a very common thing where nobody ever goes out and checks on those truck washers or trailer washers … so that's a big hazard then for that second failure even if we have the right protocols in place."
The third failure then is when the pigs become infected, when the virus essentially is transmitted from the pathogen-carrying agent, in this case the livestock trailer, to the pigs in the herd.
"If we introduce them directly into the herd without isolating them first, then that's likely going to lead to that last failure," Holtkamp says. "Now we got infected gilts with nose-to-nose contact with other pigs in the herd and so very likely going to have an outbreak there."
Holtkamp has dozens of "hazard tales” from conducting investigations on farm. Employee entry is the most frequent carrying agent entry event, he says, and not only is the number of entries into the farm a concern, but also the lack of knowledge and control over what employees do when they're away from the farm.
For example, during a PRRS 1-4-4 L1C variant investigation last year, an employee had been transferred from another PRRS positive sow farm just before the outbreak.
"Their last day on that other PRRS-positive sow farm was April 30, and they had the weekend down, and then they started Monday morning, May 3, on the sow farm we were investigating that had the outbreak," Holtkamp says. "Clinical signs were first observed on May 9, about six days later, and the isolates for both of these sow farms, the one he worked on and then the one that had the outbreak, were 99.3% similar."
Management was aware of the risk and had the employee detail their car over the weekend, but the precaution taken appearantly fell short.
"The other piece of evidence we had there, to sort of raise the alarm bell on this one, was the employee worked in farrowing at both farms," Holtkamp says. "The outbreak in this farm that we were investigating started in farrowing, at least that's where they saw the first clinical signs of sows off feed. They saw that first in farrowing and that's where he worked."
Another hazard tale Holtkamp refers to is the case of the "replaced feed line." After a PRRS outbreak investigation, it was found a company repairman had come in and fixed a feed line and a piece of plastic from the lining of a feed bag got caught in it.
"By this time, I had done several outbreak investigations for this production system and the herd veterinarian, I'd done three with him before this. Every time I would ask him, 'do you allow parts or tools or supplies to be transferred from one farm to another?' And he was adamant, 'Nope, we don't allow that. Never happens,'" Holtkamp says. "Well, after this one happened, he went in and dug into this a little bit more."
There was an outdoor parts yard that the maintenance guys kept, and if they had some extra parts left over from a job, they would dump them out there and then if they needed them, they would go pick them up.
"That's what happened in this case, that auger came from that outdoor parts depot or yard, and to make matters worse then, the farm manager was gone that day that they did the repairs," Holtkamp says. "Nobody on the farm knew, did he shower in/shower out? Did he ever go out and have to get extra parts or some tools from his truck? So, this maintenance guy worked in perfect anonymity while he was out there apparently."
Confirmation came from diagnostics as well as the first clinical signs that were observed five to six days after the repair, exactly in the same spot where the feed line was fixed.
Finally, Holtkamp like to share the "pregnant girlfriend" hazard tale, a case from North Carolina where the pork production system's policy did not allow employees on sow farms to live with anyone that works at another swine farm outside the company. While they didn’t live together one of the employees did have a girlfriend that worked on a sow farm for another company.
"They didn't live together so they weren't technically violating the policy, but just right before the outbreak, she got pregnant," Holtkamp says. "Again, highlighting that we have no control, and sometimes very little knowledge, of what employees do when they're away from the farm."
Overall investments in biosecurity across the industry have been effective, Holtkamp says but it has not been sustainable. Conducting a hazard analysis is a good start to maintaining a steadier level of vigilance. After all, putting together biosecurity standards is not going to be an effective practice if those protocols are not first addressing the most significant hazards.
"Are those really addressing the things that are putting our firms at highest risk or making them most vulnerable?" Holtkamp says. "If we can't answer that first, then just going to lists of biosecurity practices or the standards and doing those things is just not going to be very effective."
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