"We don't know which biosecurity measures really work," says Sandy Amass, a Purdue University veterinary researcher.
While there are no clear-cut answers, researchers are learning more about biosecurity protocols that may or may not keep hog herds healthy. Current biosecurity decisions are largely based on opinion and experience rather than scientific research.
"Either what we're doing is right or we're spending a lot of money on things that aren't right or necessary," says Amass. That's why she and other researchers are looking into the biosecurity decision-making process.
"People have the impression that biosecurity is common sense, and that we can control diseases," she adds. But common sense didn't prevent the foot-and-mouth disease outbreak in Europe.
Until the industry learns more about the science of biosecurity, you're at risk. You could be spending extra time and money on unnecessary biosecurity measures.
Amass says part of the problem specific to FMD is that the most recent papers published on the disease occurred in the early 1970s. Scientifically speaking, these reports were based on small sample sizes and may represent different strains of the FMD virus than is causing trouble today.
According to a 1969 article by G.E. Cottral, FMD can live in soil, one to 21 weeks; manure, one to 24 weeks; brick, adobe or wood, two to 11 weeks; haystacks, four to 29 weeks; water, three to 14 weeks; houseflies, 10 weeks; clothing and footwear, three to 14 weeks. Even though these figures are more than 30 years old, they're the best source available.
Still, biosecurity measures are the industry's best attempt to keep disease out of pork operations in the first place.
Bottom line, everyone involved in the pork operation, including yourself, managers, employees, veterinarians and family members, need to respect biosecurity protocols.
"Since most biosecurity procedures have not been scientifically validated, we must do the best we can with the information that we have to date," says Amass. "However, I feel a dangerous premise is set when we recommend procedures that have been shown to be scientifically ineffective, just to give the perception that we are doing everything possible to prevent disease. Encouraging people to perform biosecurity tasks that are known to be worthless damages our credibility as veterinarians."
Amass and other Purdue researchers are working to develop science-based biosecurity protocols. In the real world of raising hogs, there are many risks that researchers and veterinarian can't control – such as facility siting, pig proximity and aerosol disease transmission. Therefore, Amass and her fellow researchers focused on things they can control – specifically the role of people in transmitting pathogens.
"These details are important because people will most likely track pathogens among groups of pigs before we see any clinical signs of an outbreak," she adds.
Proper boot cleaning is an issue Amass has studied in detail, and she has found poor boot bath maintenance on most pork operations. Specifically, the boot baths are contaminated with organic matter.
"The whole idea is to get the manure off first, before you put your boots or equipment into the disinfectant," she explains. "If you don't, the efficacy of the bath disappears, even if it's only used once." Also, follow the label instructions for changing the bath – something few producers do religiously.
Amass and fellow Purdue researchers evaluated some common disinfectants, including Cidex Formula 7,* Nolva- san, Chlorox, Betadine Solution, 1Stroke Environ and Roc- cal-D Plus, using various boot-bath protocols. The purpose was to encourage effective clean ing practices.
Based on this research, she concludes the basic principles of proper boot baths include:
- Scrubbing visible manure from boots enhances bacteria removal. Simply walking through a boot bath won't reduce bacterial counts. Standing in a boot bath for up to two minutes without scrubbing off the manure does not significantly reduce bacterial counts. The only exception involved a cost-prohibitive disinfectant.
- Scrubbing visible manure off in a water bath is just as effective as scrubbing manure off in a bath of the disinfectants tested, in terms of reducing bacterial counts.
- Scrubbing off manure in a clean disinfectant boot bath reduces the bacterial count more than scrubbing boots in a contaminated boot bath.
- Boots that were scrubbed free of manure and then soaked in Roccal-D Plus for five or more minutes met the best standard for disinfection.
Amass admits that time constraints inhibit the proper use of boot baths in real-world pork facilities. "Spending time and money to implement boot-bath procedures on a farm without using them correctly is a waste of resources," she contends.
Even though you can increase employee biosecurity awareness by having them step through boot baths, it could place your pigs at risk by allowing contaminated boots to enter your facilities.
Installing boot stations with hoses and brushes can assist the manure removal process. When you choose a disinfectant, Amass recommends selecting a brand based on efficacy, cost, ease of use and environmental friendliness.
Controlling people flow in and around production facilities, is a major biosecurity component, says Amass. Unfortunately, there isn't much research documenting people movement, the effectiveness of showering policies or time limits away from other pigs.
She notes that researcher R.F. Sellers, Cambridge, England, studied people who came in contact with animals infected with FMD. He isolated FMD in the nose of one person at 28 hours but not after 48 hours. Nose blowing and normal washing were not effective in eliminating the virus. Plus, cloth or industrial masks didn't prevent people from inhaling the virus.
A year later, Sellers reported that people transferred FMD to one steer after coming in contact with FMD-infected pigs. Amass says that results from Seller's work appear to be the origin for the "48-hour rule" used by many producers even though humans may harbor different viruses and bacteria for longer or shorter periods of time.
In other studies, researcher D.E. Wentworth, reported the transmission of the swine influenza virus to humans despite the use of Biosafety Level III containment practices (coveralls, boots, goggles, gloves, hairnets and dust masks).
Studies with the porcine reproductive and respiratory syndrome virus have been less conclusive, says Amass. People could potentially become contaminated with the virus but remain unable to transmit it to healthy pigs.
Amass plans to research post-weaning E. coli transmission with Pat Halbur, an Iowa State University veterinarian. In addition, Purdue researchers will continue to look at on-farm sanitation strategies.
Based on the research available, it appears that the risk of transmitting diseases between people and swine varies with the pathogen. It's essential to determine the risks individually.
There are some basic biosecurity procedures, that while they need to be studied, require a low-cost commitment, says Amass. They include:
- Have employees tend to the sickest pigs last.
- Minimize or eliminate outside vehicles and visitors from entering your operation.
- Isolate new pigs before introducing them to your herd.
- Have your veterinarian test for various diseases and develop a herd-health profile.
- Make sure everyone knows the signs of foreign animal diseases –FMD, classical swine fever and African swine fever – and that they watch for suspicious symptoms.
You can and should take measures to help prevent disease transmission, but nothing is perfect. Although more research is needed, it's up to you to monitor available resources and make adjustments as new information surfaces.