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Preparing for a potential ASF outbreak

By Staff | Mar 6, 2020



As part of their annual PorkBridge education series, the Iowa Pork Industry Center kicked off the several week-long program with an over view of African swine fever.

Pam Zaabel, with Iowa State University, presented the segment with the intentions of providing a better understanding of why ASF is such a threat to the United States and steps that can be taken to help protect animals.

“African swine fever, or ASF virus, is a very large and complex virus,” she said. “It infects both domestic and feral swine, causing many animals to get sick.”

Because ASF is such a large virus, Zaabel said discovering a vaccine has been made difficult.

There is some promising news, however.

“It was recently announced USDA did discover a vaccine candidate that protects against clinic signs and prevents shedding when challenged with the Georgia strain, which is the strain which is currently circulating in Eastern Europe and in Asia,” she said.

The biggest concern surrounding the ASF virus, in addition to what it does to the animals, it is highly resistant in the environment. Especially, according to Zaabel at low temperatures and in uncooked and undercooked meat products.

“It can remain viable in those products for a long period,” she said. “It can also survive in blood, feces and tissues. It can live several days in feces at room temperature; at least a month in contaminated pig pens and up to a year and a half in blood stored refrigerated temperatures.”

Zaabel went on to say it can remain infectious for many days, as well, in boned meat and in several years in frozen carcasses.

“Of course, that is a huge concern when animals might die from this virus how we dispose of those carcasses,” she said. “Are they going to remain infectious or are we actually killing off the virus?”

Transmission of the virus

Zaabel said the transmission of the virus can occur by direct contact with the most common exposure done through saliva, excretion from the eye and nasal discharge.

“This is a problem because it is found in all secretions from the animal,” she said.

ASF can also be transmitted from the movement of humans.

“On our clothing, footwear, equipment and vehicles – we have been seeing that happening in other countries. We worry if we got African swine fever here, that we could spread it through those same channels,” she said.

Soft ticks have also been playing a role in the spread of ASF.

“We are not sure the role, exactly, soft ticks could play here in the United States,” she said. “Researchers are also looking at other biting insects such as mosquitoes and biting flies to see what roles they could play in the transmission of this virus.”

Zaabel said there is more concern about what ASF can do to an animal. If introduced into our pork supply in the United States, it could put a stop to all pork exports and have a very significant economic impact on several commodity groups.

“We won’t be able to trade,” she said. “Other countries will not want our meat products as we figure out where the disease is in our country. That’s going to put more product on the domestic market and it’s going to affect a lot of people across U.S. agriculture.”


Traceability by utilizing a Premise Identification Number (PIN) is one of many actions that can be taken to help protect an animal site.

“The PIN is a number that is tied to the site and when we talk about our information as people, we talk about how our social security number ties a lot of our information to us. That Premise ID number is what ties all information to that site. It ties the information by animal movement, diagnostic lab submission results and so on. It’s very important we include that PIN when we talk about animal movement or we have a diagnostic laboratory submission.”

On the site, Zaabel said it is also very important to not only record animal movement, but to track people on and off the site by maintaining an entry logbook.

“Last fall, we had an African swine fever exercise and we found that producers that tracked those records electronically, could provide that information to the animal health officials much faster, to be able to find where the virus was, or even to prove that they weren’t connected to infected sites,” she said. “They could show through these movement records that things from infected sites did not come on to their sites. That’s all a part of traceability.”


Zaabel said studies have shown that strong biosecurity does work.

“You have the power to follow along and implement biosecurity measures on your sites,” she said. “Human actions are most often responsible for the spread of African swine fever that is what we are hearing in other countries that we spread it on our clothing, vehicles, how we move animals around and in food products. That is something we have the power to control when we are the ones that are spreading the virus around.”

On the Secure Pork Supply (SPS) website, securepork.org, Zaabel said producers can find several resources that have become available on making a plan and other biosecurity measures to help protect their sites.

“A lot of work is being put into writing site-specific biosecurity plans,” she said. “Some people are writing their own plans, some are using the resources that are available. There is a template on the website.”

Those biosecurity plans, Zaabel said should include a map of the site.

“Basically, it’s something that you can share with people that come to the site, or with those working on the site so they understand the path they are to follow where they are to go,” she said.

A plan should also include a perimeter buffer area. This area is what surrounds enclosures. Crossing into the area only occurs through access points and that is when biosecurity measures must be put into place.

“That is the area that is around the enclosures where human and vehicle traffic has taken steps to reduce the potential for contamination biosecurity layers, or we need extra hurdles. The more hurdles or more layers the virus has to go through to reach the animal, that will help reduce the risk of the virus entering the building,” she said.

Line of separation, Zaabel said, just like perimeter buffer area is another barrier to help separate the dirty, or potential sources of infection from the clean area.

“For animals housed indoors, we usually refer to the line of separation as the walls of the building,” she said. “For animals that are outdoors, the line of separation may be the fence enclosure. If you are going to cross a line of separation, it requires following biosecurity measures that could be walking through the doorway.”

What are some biosecurity measures to be considered?

“We don’t dictate that it has to be a shower in and shower out, but we do talk in the plan about having site specific coveralls, or clothing. Site specific footwear and washing hands coming to the site clean. All of these things we can do, to reduce the risk of infecting animals,” she said.

Zaabel stressed the importance of coming to a site clean.

“The footwear we wear to the site every day needs to be clean and it is important to track all of the people coming onto the site with a log book,” she said. “Public health officials may ask who has been on the site recently so you can provide that information to them and we need to follow the biosecurity measures of that site. It is important if it says to use the shower facilities, that we actually shower. Use shampoos, use soap, actually use the shower and don’t make it a quick in and out. If we have hand washing available we take the time to use soap and wash our hands. Change into site specific clothing and footwear. Again, more hurdles, more layers and every step that we take is one more way we are protecting our animals on our site.”

Inputs and outputs include anything coming onto the site such as pigs, feed, removal of carcasses and more should also be a part of a biosecurity plan.

Zaabel said there is an input/output document available at securepork.org that will help producers think through several of the different inputs -how often they come onto the site and if they have the ability to not bring that input in as frequently?

“Every time equipment, vehicles, people come on to the site they present a risk and of course the risk they present depends on how they’ve been handled and exactly what they are doing before coming to the site,” she said. “That is what the input/output document provides you think through those riskier events, how often they occur and if you can reduce the risk of them coming onto the site.”

When you consider the vehicles and equipment coming onto your site, Zaabel said there are several things to consider.

“Did they come from another production site? Were they cleaned before they came to the site? Or did they come from a site where they could potentially bring any virus from that site they were previously at? I know that it is not always easy to clean and disinfect especially in adverse weather conditions, but if there is a way we can clean those vehicles or keep them farther away from the buildings – think through how you have vehicles and equipment coming onto the site and be aware you may be asked to follow some different biosecurity measures around those vehicles and equipment,” she said.

Carcass removal has become a hot topic surrounding a potential ASF outbreak.

“Are the approaches you are using right now, are you doing it in a biosecurity manner? How are you getting them outside of the animal buildings? Are they being disposed of on the site or are they being moved off the site? Moving dead animals from the site can be a very risky event. We talk in the Secure Pork Supply Plan on having a plan in place and implementing that so you are doing it in a biosecurity manner,” she said.

Manure management is something else to consider when making a biosecurity plan.

“That is a large risk. I realize it is not exactly easy to disinfect manure handling equipment, but if you have some biosecurity measures in place, you are helping protect your site,” she said.

Keeping rodents, wildlife and other animals out of sites, is also important, Zaabel said.

“We definitely need to keep biosecurity measures in place to keep them out of our buildings and out of our pens,” she said. “There are times I hear were a dog rode with the owner to the site, gets out and enters the animal buildings and we just can’t allow that to happen. We need to keep them out of our animal enclosures.”

To help implement biosecurity plans, Zaabel said some sites are assigning biosecurity managers.

“Our hope is that biosecurity managers may be asked to provide input on the biosecurity plan or are helping to write and implement measures of the plan prior to an outbreak,” she said. “As the biosecurity manager, it’s important for their role to also make sure everyone on the site is trained in biosecurity. It is really difficult to expect people to follow all of the rules on the site if they really don’t know what they are, or understand what their purpose is. Biosecurity is a very important component.”

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