Farmers Gain Weapon Against Devastating Pig Virus

A disease that killed off at least 10 percent of the nation’s hogs in the last year is starting to threaten farmers again as colder weather approaches.

But they have new tools to fight the ailment, porcine epidemic diarrhea virus. The Agriculture Department has conditionally approved two vaccines, and a third is on the horizon.

“I’ve been in this industry for 37 years, and I have never seen it pull together like it has in this crisis,” said Bill Marks, chief executive of MJ Biologics in Mankato, Minn., which is hoping to get the Agriculture Department’s approval soon for the third vaccine. “The leadership of our trade associations has been fantastic, and the collaboration between universities and private industry has been phenomenal.”

The virus infects sows and is passed from them to their piglets, which are particularly vulnerable. About half of the nation’s six million sows have contracted it, and some have lost entire litters to the disease, according to the National Pork Producers Council.

Howard Hill, the council’s president, told attendees at the World Pork Expo this summer that 1.3 million pigs died from the virus last January alone. The need to bury so many carcasses has even raised concerns about the effect on groundwater.

Circle Four Farms, a unit of Smithfield Foods that is the largest hog farm in Utah, was among the latest operations hit by the virus, said Dr. Tom Burkgren, executive director of the American Association of Swine Veterinarians. For reasons that are unclear, the virus is not as active in warm weather, but since temperatures have started falling, more farms are reporting outbreaks.

“We’re concerned going into the fall that we will see the same uptick we saw last fall and winter,” Dr. Burkgren said. “January, February and March were really tough, so everyone is holding their breath and keeping their fingers crossed.”

In June, the Agriculture Department set aside $3.9 million to develop vaccines against the disease, but none of that money has gone to the two it has licensed for use thus far. One is made by Zoetis, a titan of veterinary medicine; the other by Harrisvaccines, a company founded by a veterinarian and former animal science professor at Iowa State University, where much of the research on the virus has been done.

The licenses are conditional, meaning that the companies have met the Agriculture Department’s requirements for safety and purity and have a reasonable expectation of efficacy. “Preliminary studies on these vaccines have been promising, and they’ve shown sufficient data that we think the vaccines will be effective,” Joelle Hayden, a department spokeswoman, wrote in an email.

The vaccines are administered to pregnant sows infected with the virus during the weeks or days before they give birth; none are for use on sows with no sign of the virus. They work by increasing a sow’s immunity, which she then passes on to her offspring through colostrum and milk.

The Zoetis vaccine went on the market in September. Elinore White, a company spokeswoman, said it had been shown to be safe in a field study that also suggested it was effective. She said Zoetis was still preparing data on efficacy in the field and potency, which it will need for full licensing.

Harrisvaccines and Zoetis would not provide the names of veterinarians or farmers who have used their vaccines.

The Harrisvaccines product, the first that the Agriculture Department approved, was developed by modifying a gene sequence from a Chinese strain of the virus, said Joel Harris, the company’s head of sales and marketing.

“If there’s anything good to come out of this, it’s the realization of how vulnerable the ag industry is to these animal diseases,” Mr. Harris said.

Pork producers are often reluctant to disclose that they have been affected by the disease, although they are required to report outbreaks to the Agriculture Department.

Dr. Burkgren of the veterinarians’ association said he had spoken with vets who were using the Harrisvaccines product. “It’s not a cure-all, apparently, but it does help stimulate sow immunity and get farms back into production faster,” he said.

Jose Vera, a farm manager, has used the Harrisvaccines product and tested the one from MJ Biologics at two pig farms with about 6,000 hogs in Mankato, the home of MJ Biologics. Sows on the farms have displayed signs of the virus for about the last six months, he said.

Mr. Vera said the MJ Biologics vaccine seemed more effective. “Most of the piglets did not get sick, and if they did, it was just for a little bit,” he said.

About 17,000 of the 35,000 pigs under the management of Protein Sources, a company that oversees farms and offers financial and other services to swine producers, have been infected with the virus, according to Paul FitzSimmons, the managing partner. As a result, 60,000 to 70,000 of their piglets have died.

The company has tested the MJ Biologics vaccine in 75 sows and compared the incidence of diarrhea, or what the industry politely calls scouring, among their piglets with that among the piglets of 75 sows from the same farm that did not get the vaccine.

“We had great losses of piglets in the control group,” Mr. FitzSimmons said, “but very few of the piglets born to vaccinated sows showed any sign of scouring.”

Dr. Mark Wagner, a swine veterinarian in Minnesota, cautioned that not enough data was available on any of the vaccines to understand how they worked or their effectiveness. Additionally, he said, some natural immunity has started to develop in the nation’s hogs, which will complicate assessment of the vaccines.

“We’ve made progress against this disease across a lot of different avenues, from diagnostics to better sanitation, and what I hope is that people don’t start thinking these vaccines are a silver bullet,” Dr. Wagner said. “They are progress.”