Many groups of people define and use the word risk differently. For those involved in hog production, risk is used in the context of disease risk, hazard risk and financial risk. For those of us walking the planet in 2020, we are bombarded with the word risk daily as we navigate through the COVID-19 pandemic. For example, you might be wondering, is it riskier to go to the park and play tennis or to a night club? Answer: night club (1).
My point is that each person will have a different perception of risk. And, each person needs to understand that, especially in the world we now live in, most activities present some degree of hazard and that risk is present any time a potentially hazardous activity is undertaken.
As a veterinarian and a member of the Secure Food Systems team at the University of Minnesota (2), for the rest of this article, I will use the word risk in the context of the work done to try to determine or assess the risk of a foreign animal disease, like foot-and-mouth disease or African swine fever, infecting pigs in the United States. I will use, as an example, an FMD risk assessment that was completed in February 2020 (3) to explain how we attempted to determine the risk of FMD spread associated with the movement of weaned pigs during a FMD outbreak in the United States.
Since most of us are not aware of the actual risks of all the day-to-day sow and weaned pig activities occurring on farm, we often make decisions whether or not to undertake activities based on convenience, likes and dislikes, and various perceptions formed from our experiences. To capture these perceptions and attempt to calculate risk more precisely, it is important to gather a workgroup of producers, packers, veterinarians, state animal health officials, federal (e.g. USDA) regulatory personnel and scientists to work together to assess the risk.
Over the course of five years, we studied the science, performed mathematical models and reviewed all the findings with the workgroup to evaluate the risk that movement of live pigs during a FMD outbreak in the swine industry in the United States will result in the spread of FMD virus to other premises with swine. Specifically, the assessment evaluated risks of FMDv spread due to the movement of weaned pigs coming from a sow farm located in an FMD control area. To do this, we made certain our assumptions and assessments were applicable to swine production in the United States. We also kept in mind that, even in the midst of an FMD outbreak, pork producers would be using both standard swine production practices and enhanced biosecurity practices such as those proposed by the Secure Pork Supply Plan (4).
You may be wondering why an FMD risk assessment was completed when ASF is still ravaging the global swine industry. The reason is that an FMD outbreak in the United States may impact multiple livestock species, and so the impact for U.S. agriculture as a whole would likely be greater. This is an important concept to grasp when trying to understand risk.
Risk is not only a four-letter word, it is much more than that when you consider the impact or consequences of something happening. Risk can actually be calculated by using a risk equation that defines risk as equal to the likelihood multiplied by the consequences. Calculating the consequences of an event happening can be quite difficult and varies by farm, region and person. Even though multiple livestock were considered, we did not take into account the impact or potential result of each event happening. To keep the focus on disease prevention and planning, the risk assessment was limited in scope to pigs only and did not factor in all aspects of the potential consequences. Now, with that in mind, from here on, instead of using the phrase, "likelihood of," that plain old four-letter word, "risk" will be used.
The risk assessment was conducted to identify pathways of FMDv transmission due to the movement of weaned pigs, and to assess the risk of carrying virus off an infected farm and causing infection to another pig farm. The likelihood of that risk occurring were examined for these six questions below. For each of these questions, we thought about farms in different locations, different sizes and in several different situations, such as only having their standard farm biosecurity measures in place to increasing their biosecurity and having more strict, enhanced outbreak-specific measures put in place.
- What is the risk that a sow farm in a control area becomes infected with FMDv?
- What is the risk that we are not able to detect FMDv on the sow farm prior to moving weaned pigs off the farm?
- What is the risk of FMDv shedding from pigs during movement?
- What is the risk that pigs would get FMDv if they were put on dirty (FMDv-contaminated) trucks?
- What is the risk that pigs on a truck can get infected by FMDv in the air?
- What is the risk that other pigs at the farm get FMD after the weaned pigs arrive?
There are a lot of factors that are evaluated when trying to answer the questions above. If you have time on your hands, for example, you find yourself at home instead of at a major league baseball game due to your desire to reduce the risk of COVID-19 spread, reading the full risk assessment is necessary to fully understand it and appreciate the limitations of the findings based on the scope and assumptions. If time is still in short supply, then here is the very brief summary of the overall findings and conclusion.
It was concluded that there was a moderate risk that movement of weaned pigs from a sow farm in a control area during an FMD outbreak results in FMDv infections at the off-site nursery or wean-to-finish farm if the sow farm put in place some basic surveillance and biosecurity measures. This should not be too surprising, considering that common diseases such as porcine reproductive and respiratory syndrome virus and porcine epidemic diarrhea virus are moved from farm to farm with weaned pig movements. The bigger question that should be asked now is, "Can the risk be reduced?" The pleasant answer is, "Yes, we can!"
If pork producers adopt enhanced biosecurity measures, such as some of the Enhanced Biosecurity Recommendations as outlined in the Secure Pork Supply Plan, the risk can be lower. If we invest in the time and research needed to study the biosecurity measures that have the most impact, develop accurate and timely diagnostic tests, and strategically implement these measures and tests during an outbreak, then the risk can be lower still. But the risk can never be zero, because there is a small amount of risk in everything we do in pig production and in life. That might be why risk sometimes seems like a four-letter word.