Sometimes, a disease breaks from animals into the human population and causes widespread concerns over contagiousness, immunity and health outcomes.
With the recent COVID-19 pandemic barely in the rearview, that might be why when an illness spreading among livestock– like highly pathogenic avian influenza (HPAI), which has plagued commercial and wild flocks for two years, or African Swine Fever Virus (ASFV), a contagious virus endemic to parts of east Africa and saw concerning spread in some continents in the early 2020s – the primary concern among the public is often whether this will spread to humans or even be the “next COVID.”
Many of these diseases, including ASFV, are not known to infect or affect humans. Some do but have very mild symptoms or show no signs of human-to-human transmission.
The latter is the case for the recent HPAI outbreak, which did spread from livestock to some humans but, as of June 2025, according to the Center for Disease Control, has not shown any signs of person-to-person spread. Risk to the general public remains low.
Good news, right?
Not so fast, say experts.
Just because something will not acutely affect public health does not mean the public should not be concerned. When a disease spreading among livestock results in the inevitable culling of herds and flocks, the results can be devastating for producers. In the case of HPAI, consumers have already seen these effects passed onto consumers through skyrocketing egg prices and fluctuating availability of poultry products. There’s also a risk of profound mental health effects on producers as they’re forced to make difficult decisions about their livestock.
These outbreaks have stressed the importance of biosecurity practices worldwide. But beyond wearing PPE such as booties and gloves in barns, Elizabeth Ferry, extension educator for Berrien County with Michigan State University says manure management plays an unignorable role in the matter.
Be vigilant
Ferry specializes in pork, and is part of the team working on secure pork supply plans including disease response and on-farm practices for the state of Michigan.
“It started with, ‘hey, this is a great idea,’” she said. But then, the swine industry was hit with Porcine Epidemic Diarrhea Virus (PEDV). “We broke with that, so [biosecurity for swine] becomes an even bigger issue. Then we had African Swine Fever Virus.” While ASFV has not yet been recorded in the U.S., cases in the Dominican Republic brought concern for the industry. “We used to be able to say there was an ocean between us and ASFV, and now there’s not… secure supply became very important.”
Work in Michigan has focused on biosecurity on the farm. “Biosecurity is the key when we think about the movement of animals. If we are in a disease outbreak, we want to be able to permit healthy animals [to move].”
Manure itself, as well as the equipment, the people running it and different processes can all be potential vectors for the spread of fomites. A 2023 study assessed the frequency of Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) RNA and PEDV RNA detection in pit samples from midwestern wean-to-finish barns and the likelihood of increasing PCR-positivity of pig oral fluids after manure pumping. The odds of a PRRSV outbreak within a four-week window were greater when the site was pumped and was in close proximity to a field receiving manure. The odds of a PRRSV-negative barn becoming PRRSV-positive increased significantly after manure pumping. Similarly, a pork checkoff study sampled 30 manure pits rom barns in southern Minnesota and northern Iowa. When tested by swine bio assay, two barns on four months after having PEDV positive pigs were positive.
Ferry acknowledged that when it comes to custom haulers are not working with their own animals – but nevertheless, she says, “They have a business to protect.” That means high standards are imperative – and holistic.
From the ground up
First,workers must understand how diseases spread. For haulers, it can be through direct exposure, fecal-oral exposure or aerosolized spread. Insects or other wild animals can also be a vector.
Next, consider real-life examples. When PEDV was first introduced into the U.S. in 2013, it spread rapidly through unexposed pig populations and, following the initial outbreak, sporadic re-breaks occurred, with manure hauling identified as one of the factors resulting in re-breaks.
Then, familiarize yourself with specific biosecurity basic for different manure processes. MSU Extension recommends the following practices for manure handling and pump-down process:
- Develop a standard operating procedure for manure handling;
- Communicate with farm owners, managers and employees;
- Schedule your visits;
- Verify herd health status;
- Understand biosecurity requirements;
- Do not enter buildings;
- Develop cleaning and disinfection protocols for equipment such as spreaders, trucks, pumps and hoses (including wheel wells and undercarriages);
- Identifying a water source away from the facility or traffic patterns for the crew to use to clean the manure from said equipment;
- Maintaining equipment to minimize the risk of on-farm spills;
- Consider the need for splash mitigation;
- Use dedicated roadways for manure transport; and other recommendations available through MSU extension.
Enhanced plans
Enhanced biosecurity plans are also a necessity. Each state determines what an enhanced biosecurity plan means. In the case of Michigan, it’s been working with neighboring states Ohio, Indiana and Illinois, because of how many farmers cross state lines. “We’ve been trying to make sure Indiana’s guidelines match Michigan’s, so we’re not trying to meet different standards and we both have good understandings of what each state is going to accept into the state, because the state government is the one that can deny movement if we have animal disease outbreaks.”
But biosecurity, like other matters of safety, can also boil down to economic and social issues. Most would agree that best practices are a good thing – hence the term “best” – but finding the time and resources to implement them can be another story. Whether it’s lack of time, lack of resources or even language barriers, communicating the importance of these practices and consistently upholding them can be a challenge for some. And if they don’t see an immediate risk because it doesn’t hit them in the pocketbook, Ferry cautions to think big picture.
“We look at biosecurity as a way to manage risk… If you don’t have your plans in place for enhanced biosecurity, if we have a disease outbreak, you won’t be able to move animals, you won’t be able to move manure, you won’t be able to bring things on and off your farm if you’re in a control area, and it becomes really important to have access to that through permits.” The way to obtain those permits? Enhanced biosecurity plans.
Overall, actions taken on the farm – both systemic, widespread actions and individual decisions – can have far-reaching consequences. “It’s risk of contamination, it’s soil, water and air pollution, it’s reducing those economic losses, it’s protecting human health, and then it’s maintaining consumer confidence,” she says. “If we don’t have an industry, if we don’t have consumers who want to buy our products, then we don’t have business continuity.”•
