As the reach and mortality rate of porcine epidemic diarrhea virus (PEDv) continues to grow across the United States and into Canada, U.S. Senators Debbie Stabenow (D-Mich.), chairwoman of the Senate Committee on Agriculture, Nutrition and Forestry, and Kay Hagan (D-N.C.) penned a letter to Agriculture Secretary Tom Vilsack about the financial toll the disease is taking on the pork industry. The senators urged Vilsack to approve disaster assistance—available through the recently passed farm bill—for small pork producers affected by the virus.
It’s estimated that more than 4 million pigs—mostly piglets under 2 weeks old—have perished from PEDv. The mortality rate is nearly 100 percent for young naive pigs. “If this disease persists, pork herds will continue to diminish and producers risk going out of business,” the senators’ letter states. “Much like the rest of the livestock industry that suffered drought, fires and blizzards, these pork producers have no safety net to help compensate for their losses.”
Veterinarians and researchers alike are racing for ways to stem the spread of the disease. The University of Minnesota College of Veterinary Medicine’s Veterinary Diagnostic Laboratory developed a PEDv rapid diagnostic test last summer after the virus first presented in the United States in April. Purported to be the first of its kind, the test provided a way to quickly identify the presence of domestic PEDv strains. Other private labs followed suit.
This winter, the Veterinary Diagnostic Lab went on to develop an ELISA test to detect evidence of the virus. This provided producers a better understanding of exposure in a herd, James Collins, DVM, PhD, director of the University of Minnesota Veterinary Diagnostic Laboratory explains, allowing them to separate pigs that had been exposed to the virus from naive pigs.
At the end of March, cases of PEDv were confirmed in 28 states, with Arizona and Vermont being the most recent additions to the list. Sen. Hagan’s home state of North Carolina has nearly 500 cases confirmed with the National Animal Health Laboratory Network; Stabenow’s Michigan has 55. Minnesota and Iowa top the list with 701 and 1,521 respectively.
“It’s a highly infectious virus shed in massive amounts in the feces of pigs,” Collins says. “Wherever you find pig manure, there’s a risk.”
And with the copious amounts of waste pigs amass during production, biosecurity is essential. “Biosecurity is the best way to keep it out of your farm,” Collins says. The virus can be spread by transportation means—from facility to facility—on boots. “Humans are always the weakness,” he says.
Veterinarians on the ground are trying to combat spread by manipulating herd immunity. “Some are saying it’s being effective; some are saying it’s not,” Collins reported at the end of 2013. The method entails introducing the virus to a gilt or sow with good immunity, with the hope that immunity will pass on to the piglets and protect them from disease.
Iowa-based vaccine manufacturer Harrisvaccines says it has developed a vaccine to boost immunity against PEDv. According to Joel Harris, head of sales and marketing, the company has already shipped producers well over a million doses of the vaccine, which it calls iPED. “It’s really unique and new and novel compared to anything else used in the swine industry,” he says. “We do a lot of molecular biology. Instead of taking the whole PEDv virus, we took a gene sequence and inserted it into our production platform.” Harris says this system creates particles that look like PEDv to stimulate the immune system and allows Harrisvaccines to produce herd-specific vaccines in just four to six weeks.
Harrisvaccines—created and run by its CEO, D.L. “Hank” Harris, DVM, PhD, a former Iowa State University animal sciences professor—is working toward a conditional license from the U.S. Department of Agriculture (USDA). The company anticipates approval from the USDA this summer. Currently, iPED is an unlicensed vaccine. At $3 a dose, it is available through veterinary prescription only.
Harrisvaccines believes it has achieved what laboratories across the country have been racing to develop since the disease’s oubreak last April. However, Albert Rovira, DVM, MS, PhD, of Minnesota’s Veterinary Diagnostic Lab, says he has not seen any data to date—including from Harrisvaccines—that shows vaccine effectiveness against PEDv.
Harris counters that his company is gathering the data to prove iPED effectiveness. “We’re monitoring product data in systems that are using the vaccine,” he says—mostly in herds that have been chronic with the disease. “In those instances where people are struggling with high mortality numbers, they’ve seen an improvement in those numbers.”
He admits, however, that the jury is still out regarding efficacy in naive herds. “Customers are kind of seeing mixed results,” he says. Harris says getting good field data has been complicated. New strains of the virus keep emerging mid-outbreak, and customers aren’t always willing to run controlled field studies, he says. “A vaccine is only a tool—no vaccine is 100 percent. Biosecurity is an absolute must,” he says.
Despite all of these efforts, the industry has watched PEDv continue to devastate herds this winter. “It’s definitely a virus that we think survives best in the cold, but there’s some evidence that it could be a problem year round,” warns Collins of the Minnesota Veterinary Diagnostic Lab.
Experts agree that with or without an efficacious vaccine, the pork industry has no option but to figure out how to live with the presence of PEDv. As temperatures begin to rise, there is hope—but no guarantee—that the disease will yield to spring.