Slowing the spread of the highly infectious disease is critically important in Iowa, the nation’s largest producer of pigs. It’s a $7-billion industry that employs about 39,000 workers who care for the state’s 20.5 million animals, according to Harrisvaccines.

The reduction in the pig herd is beginning to hamper production at processing plants across the country. Iowa plants could see squeezed supplies begin to idle capacity this spring, resulting in fewer hours for workers, said Steve Meyer, president of Paragon Economics in Adel.

Tighter supplies also will drive prices higher for producers and consumers, Mr Meyer said. The cost of ribs, chops, loins and other pork products are expected to spike 10 to 15 per cent this summer as Iowans fire up their grills, he said.

“It’s very difficult to ascertain what the impact will be. Suffice it to say this is the most serious animal health situation ... we’ve faced in some time in the pork industry,” Mr Meyer said.

“It’s devastating on a farm level, but consumers end up paying for it, too,” he said.

Whether producers will be able to post higher profits depends on how hard their herds were hit by the porcine epidemic diarrhea virus, called PEDv.

“Some herd losses are worse than others,” Mr Meyer said. “On average, we think the market impact on prices will offset the quantity reductions and probably increase total revenue for the industry.”

Prices for lean hogs that will be delivered this summer hit new highs last week. Lean hogs for June delivery closed at $127.68 per hundredweight on Friday.

The PED virus can infect entire herds but is deadly for baby pigs under three or four weeks old. It poses no threat to other animals or to humans. Pork products remain safe to eat.

“It’s going to have a profound supply impact into this summer, and well into the third and fourth quarters,” Mr Meyer said. “We thought we were going to raise enough pork to give people a break on retail prices, but that’s not going to happen.”

The disease was first reported in the US nearly a year ago. It had spread to 26 states by 1 March. So far, 4,106 tests have been positive for the virus. But it’s unclear how many animals have been lost, since the government doesn’t require reporting, officials say.

D.L. “Hank” Harris, CEO of Harrisvaccines in Ames, said his company has shipped 1.4 million doses of vaccine to producers. Canada, where PEDv is beginning to be reported, has called for emergency import of the vaccine.

Dr Harris, a veterinarian and former Iowa State University animal sciences professor, said his research team is already working on a third generation of the vaccine. He expects licensing approval from the US Department of Agriculture’s Center for Veterinary Biologics this summer. That will enable producers to more easily access the vaccine.

The second generation, called iPED+, is already being shipped. Dr Harris said he sees it as more effective than the company’s initial vaccine in building the immunity of sows, which pass the antibodies to their piglets as they feed them.

The company uses gene sequencing from a virus to rapidly produce a vaccine. Harrisvaccines, an ISU spin-off in 2009, has exclusive licensing rights to use the technology for animal vaccines from AlphaVax Inc., a human vaccine company based in Research Triangle Park in North Carolina.

The technology enables Harrisvaccines to bypass traditional vaccine production techniques that require live viruses, making it safer for animals, company officials say. It also significantly shortens the time it takes the company to respond to outbreaks.

For example, PEDv was first identified last year in the US in April. “We had a vaccine on the market by August. With traditional methods of making vaccines, that’s not possible to do it that quickly,” Harris said, “especially an agent like this. This particular virus is very, very difficult to grow.”

Other pharmaceutical companies are working to develop a PEDv vaccine, while Harrisvaccines is shipping the second generation of its PEDv vaccine, available with a veterinarian’s prescription.

The vaccine is being used in herds that have not been exposed to the virus as well as in those herds that have been infected.

Dr Harris said producers are using the vaccine to boost immunity in herds that have been infected and given 'feedback', a controversial method of exposing animals to the virus to try to reduce the impact of another outbreak.

Dr Harris said producers have found that intentional exposure “helps slow down the virus ... it still hasn’t stopped the disease. That’s where we’re getting sales. They’ll use our vaccine ... to enhance a sow’s resistance.”

Warmer weather should help slow the virus’ spread and help reduce animal losses. The virus survives better in the cold, when it is harder to disinfect equipment.

Pigs are orally infected by manure that carries the virus. It takes just a speck of manure to infect a pig. It can be carried from facility to facility on boots, trucks and equipment.