More than clean boots
With all eyes still on avian influenza, it’s easy to forget about another disease that’s inching closer to the U.S.
Nearly everyone who raises pigs should be familiar with the possibility of African swine fever (ASF) eventually arriving in the U.S. With approved biosecurity measures in place, producers of all sizes can help prevent entry and spread.
Many ASF cases, especially in the case of pigs raised outdoors, are transmitted by wild boar (feral swine). These animals are present in North Carolina, Virginia, Pennsylvania and New York. There’s also a feral swine population in New Hampshire, which threatens to spread to other New England states.
Veterinarian Nele Caeckebeke, Ghent University, Belgium, explained the concept of biosecurity: “Biosecurity is more than washing hands or changing boots,” she said. “It’s a set of management tools that farmers, integrators and visitors do daily. The biggest, most important and most challenging part of biosecurity is that it must be part of people’s daily habits. The principles are straightforward, but daily implementation is the most challenging part.”
Caeckebeke reviewed five biosecurity principles and said that when people do a good job with biosecurity, animals remain healthy and antimicrobial use is minimal.
The first principle is keeping diseased animals separate from healthy animals. However, indirect contact is also a key factor. A simple mistake can easily initiate disease transmission from one sick animal to a group of healthy animals. In some cases, disease may not move directly from a sick animal to a susceptible animal, but is spread indirectly through farm vehicles, feed, vermin or people.
Ideally, sick animals are always separated from healthy animals. Since that isn’t always possible, or because a worker might forget, Caeckebeke suggested creating a barrier between dirty and clean (healthy and susceptible) animals.
“When you implement biosecurity measures, you have to do it in a consistent manner,” she said. “Weekends and holidays are the toughest. It’s better to have fewer measures and implement them rigorously every day instead of having a lot of measure that are only implemented once a week by a few team members.”
The second principle is that not all biosecurity measures are equally important. Disease is transmitted in many ways, so one measure might be more important than another. Producers should analyze and prioritize measures.
For example, aerosol transmission is often a lower risk than through live animal contact. Based on what is currently known about ASF, the virus is not transmitted through the air.
Third, the goal should always be to reduce infection pressure that is always present on a livestock farm. “We want to have a good cleaning and disinfection the moment barns are empty,” said Caeckebeke. “Animals should always have sufficient space to avoid fighting, which induces stress and takes away energy that should go to meat production.”
The fourth principle is that size matters. Small farms require good biosecurity, but larger farms must strengthen biosecurity measures to manage the increased risks inherent with higher animal populations.
The fifth principle as frequency. A small risk can quickly become a big risk so farmers must always remain alert for the smallest signs of illness and immediately isolate those animals. Ensure workers are handling sick animals last, followed by thorough hand washing and a change of clothes.
“If a disease has a very low chance of being transmitted through your hands and you are touching animals several times a day, this small risk can become substantial if it’s occurring many times,” said Caeckebeke. “It also depends on which disease is involved.”
Measuring biosecurity is a key factor in the process. Establish a starting point and follow recommendations and practices to improve biosecurity on the farm. One good practice is to avoid purchasing animals and introducing them to the farm unless they come from a trustworthy source that has excellent biosecurity measures.
“Put animals in quarantine for a long enough period of time to make sure you aren’t introducing disease,” said Caeckebeke. “Limit the number of visitors to barns to the absolute minimum and register every visit. Everyone who comes onto the farm, including the farmer and any employees, must wear, at minimum, clean and disinfected farm-specific boots, clean and farm-specific clothes or coveralls.”
She added that hand washing is one of the easiest and simplest measures to prevent disease from coming onto the farm and suggested everyone wash hands prior to entry.
Transport trucks and/or trailers bringing in or removing animals present a biosecurity risk. Make sure vehicles and trailers arrive clean and don’t contain pigs from other farms or diseased animals. Truck drivers should never have access to barns with live animals.
When pigs are raised outdoors, be vigilant about who visits the farm. Ideally, visitors who raise pigs on their farm should wear clean clothing and disinfect boots prior to coming onto the farm. Anyone who has travelled from a country known to have ASF should not visit a farm with pigs for at least two weeks.
If the farm owner is aware of a wild boar population in the area, the farm and all feed storage areas should be securely fenced. When possible, double fencing to keep wild boars out is ideal.
Anyone raising pigs or working on a pig farm should have no contact with live or dead wild boar. An insect pest control program with netting traps helps prevent disease transmission. Pets should not be allowed in barns. Dogs and cats tend to eat whatever they find on the ground, so if there is a disease outbreak and the dog or cat has been in contact with a deceased animal and have contaminated themselves, disease is easily introduced to livestock.
“I always say if your dog or cat is wearing protective clothes like boots and coveralls and they wash their little paws, they’re free to go in,” said Caeckebeke. “But please try to keep them out of the barns.”
For complete biosecurity guidelines, visit aphis.usda.gov/animal-disease/swine/protect-pigs.
by Sally Colby
