KNOWN as porcine epidemic diarrhea virus (PEDV), the new-found virus is pushing biosecurity to new levels on U.S. hog farms, and rightly so, considering how easily it spreads.
PEDV poses no known public health or food safety concern, but it hits fast, and in certain ages of pigs, it hits hard, with 100% mortality in piglets fewer than seven days old.
As the hog industry works to reduce the risk and losses associated with the virus, important biosecurity lessons are being learned from which most livestock and poultry production operations can benefit.
"This is a very, very infectious virus," veterinarian Keith Aljets said of PEDV during a recent Passion for Pigs conference in Columbia, Mo. "It is way more infectious than transmissible gastroenteritis virus and (porcine reproductive and respiratory syndrome)."
Aerosol transmission has not been confirmed, but PEDV has occurred through animal-to-animal contact and fecal-oral transmission. Incubation in individual pigs may be as short as 22-36 hours or two to four days at the herd level.
As feared, the cold weather and closing up of barns has really ramped up the virus and the resulting number of new cases, Aljets said.
The latest available statistics indicate that more than 1,700 cases of PEDV have been confirmed in the U.S. as of Dec. 15, 2013. Some following the situation suspect that the number is too low and not truly representative of the full extent of the situation that exists. On average, some 30 new cases of the virus have been reported each week since cold temperatures have set in.
The infectious nature of PEDV has even reportedly resulted in some restrictions at local convenience stores in areas where the virus has been identified and pig populations are high. Farm workers are able to pump gas but are not being allowed to go inside the service station with the footwear they wore on the farm unless it is covered with a plastic, disposable boot.
PEDV is certainly not a good thing, but Aljets suggested that it is perhaps a blessing in disguise as it should help the industry firm up its overall approach to biosecurity. If this were foot and mouth disease or swine fever, it would be a whole different scenario right now, he said.
"We can get through PEDV, but it is going to take work on all our parts, and we, as an industry, really need to do all we can to learn from it so we can prevent other diseases from entering our borders," Aljets explained.
It is thought that PEDV takes its toll by chipping away at the villi in the intestines of pigs, making it difficult to absorb liquid at a time when severe diarrhea is also occurring. The result is rapid dehydration and a fast death in pigs that are most susceptible. In older pigs and sows, the virus results in slower weight gains for a week or two, but the pigs live and go on to perform just fine.
PEDV is a hot topic and has been the basis of most biosecurity discussions since the past summer, but good biosecurity is applicable to every disease out there; it doesn't discriminate and can be beneficial for everything from Escherichia coli-based scours to porcine circovirus-associated disease, salmonella and more, according to Jesse McCoy of Ivesco.
McCoy also was quick to note that proper biosecurity is very effective in minimizing one of largest risks to the hog industry: zoonotic diseases.
"PEDV is terrible and financially devastating for a farm, but a foodborne pathogen outbreak would be terrible for the industry as a whole," he said.
In the very basic sense, biosecurity is a series of management practices aimed at preventing disease in a livestock production operation and preventing its spread if, by chance, it does make its way into an operation.
Regardless of the size of an operation, the basics of biosecurity are essentially the same: control the movement of animals, people and equipment coming onto the farm, and clean and disinfect as much and as often as possible.
McCoy explained at the Passion for Pigs event that the risk of PEDV has prompted some hog production companies to take biosecurity to the next level.
"We are seeing vehicle washing moving to vehicle disinfection, the establishment of disinfection rooms for deliveries and biosecure delivery routes and quarantine restrictions on new animals coming on to the farm," he said.
Some farms are even going to the extent of using site-specific, color-coded clothing. Colored coveralls and boots are cheap compared to a disease outbreak, McCoy said. He also called for barn clothing to be laundered on site and for a bleach or disinfectant to be included as part of the process since laundry soap does not kill the virus, nor does the heat of the dryer.
Footwear disinfection has gotten more attention as well. According to McCoy, research is showing that the disinfectant solution in boot baths must be changed frequently, or it loses its effectiveness. The best rule of thumb is to switch out the liquid in boot baths every two hours.
Alternatives to boot baths include boot washes at every entrance and disinfecting powder. Veterinarians and haulers who go farm to farm may want to consider putting disinfecting powder right on the rubber floor mats in their vehicles as an added precaution.
Aljets echoed the sentiment that on-farm sanitation is critical, particularly in the farrowing operation. He recommended all-in/all-out farrowing, washing all farrowing crates twice before reuse — including removing the divider panels — and washing and disinfecting sows prior to farrowing.
The PEDV strain that has been found in the U.S. has been traced back to a very similar strain in China.
The American Association of Swine Veterinarians (AASV) encourages producers and veterinarians to pay particular attention to anything or anyone originating from outside the U.S. The group said to be especially diligent about personnel and visitors but also to consider supplies, feed ingredients, food items, etc., that might be of international origin. If the origin or the components of a particular product are uncertain, AASV recommends contacting the supplier and requesting information on the origin of the ingredients or components.
Biosecurity may be a lot of work, but considering that pigs have no immunity to PEDV, there is currently no commercial vaccine available for use on the farm and there is no documented way to save infected pigs, Aljets pointed out that the time and effort will be very well spent and a small investment to make.