DES MOINES, Iowa — A viral illness in the U.S. pig herd continues to spread even as authorities search for its origin and a way to control it.

Porcine epidemic diarrhea virus has symptoms similar to transmissible gastro enteritis and was first detected in a sow farm in Ohio in mid-April.

Swine veterinarians and industry officials are hoping that the results of a survey instrument may reveal some clues about how the virus was introduced into the U.S. herd, and they’re also hoping to find some common themes that could lead to a successful way to control its spread.

“We don’t want to leave any stone unturned,” said Tom Burkgren, a swine veterinarian and executive director of the American Association of Swine Veterinarians.

He spoke as part of a panel at the World Pork Expo.

“On May 17, when we got the official announcement, the world got a lot smaller. We have a virus that’s from outside the United States. While it’s a serious virus, it’s not as serious as foot and mouth or hog cholera or African swine fever,” he said.

As of June 10, there were 218 diagnostic case submissions that tested positive for PEDV and 199 total premises testing positive with 47 of those being sow farms, 130 growing pig premises and 20 unidentified by type.

The states involved included 102 premises in Iowa, 38 in Oklahoma, 19 in Minnesota, 10 in Indiana, seven in Colorado, six in Kansas, four in Ohio, four in Pennsylvania, three in Michigan, one in Illinois, one in South Dakota and six premises unidentified by state.

While this is the first time that PEDV has been detected in the U.S. herd, it has been around in Asia and Europe for some time.

Greg Stevenson of the Veterinary Diagnostic Laboratory at Iowa State University said the strain of the virus that was detected through a series of tests is similar to a strain from China.

“The complete sequence of the virus was 99.6 percent homologous with 2006 deposits, two different viruses from China, so we know this virus is of Southeast Asian lineage. That doesn’t mean it came directly from China here. It just means we know where it originally came from,” he told the audience in Des Moines.

Stevenson said that diagnostic labs originally tested samples from pigs thought to have TGE. However, when tests for TGE were negative, further, extensive testing revealed the virus to be PEDV.

“The earliest case that we detected is from one site, during the week of April 15, and that site was in Ohio,” Stevenson said. “We have, the following week, one positive that came from Indiana, and the week after that is when we started getting the cases in.”

The discovery of the virus in the U.S. herd was officially announced on May 17.

Lisa Ferguson, deputy director of science and technology at the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service, emphasized that the agency is collaborating with other stakeholders, including AASV, the National Pork Board and the National Pork Producers Council.

“It’s not considered a reportable foreign animal disease here in the U.S. It’s not on the national animal health reporting system list. What we’ve been trying to do is provide information, provide assistance and by providing that information, try to help avoid any overreaction. We want to avoid interstate movement restrictions. We want to avoid international movement restrictions and export restrictions, so we’ve been providing information to our state colleagues about what we know of what is going on and also to our international colleagues, our trading partners, as they ask,” she said.

Ferguson stressed that the agency is working to prevent any false panic that could be stirred over PEDV. The virus is not transmissible to humans, and it poses no threat or harm to the U.S. pork supply.

“Let me emphasize, this is not a regulatory disease. We don’t want to make it a regulatory disease. We don’t want anybody to think we want to go down that route. Our interest is the same as has been expressed already — we’re very interested in determining how this disease is spreading and, more importantly, determining the source of how it got here,” Ferguson said.

She also noted that by tracing the origin of the introduction of the virus into the U.S. pig herd, authorities and industry stakeholders may be able to better deter any other, more serious outbreaks.

“If this virus can come in, those other diseases, foot and mouth disease, even potentially African swine fever, maybe those could potentially come in through the same route, so we are very interested in trying to ascertain that piece of knowledge,” she said.

To that end, finding out more about the virus by surveying premises where it has broken could play a key role in answering questions about how PEDV got here and how it can be controlled.

“This instrument is designed to gather information about the primary herds, the index cases, the earliest herds,” said Burkgren, who went on to reassure producers that their information would be protected.

“We’re going to protect the information. There will be no identifiers on the data once it goes into the database other than the state where the case occurred.”

He said the survey, 12 pages in length, will gather all types of information about the premise.

“We’re looking for information about these herds, and we want the primary herds, but we don’t care if they’re sow herds, grow finishers or nurseries. We just want to be early in the outbreak of this. We’ll identify the risk factors — why did these farms break and other farms didn’t? We’ll be looking at everything from herd information, the number and type of pigs on the farm, what the biosecurity is, entries onto the site, inputs onto those farms,” he said.

Burkgren said researchers and industry officials are hoping the survey answers can generate answers and better-informed theories about the virus.

“We don’t know for sure how it came in, and we may not know from this survey, but our whole point in doing this is if we can at least get hypotheses generated to look further into this,” he said.

The effort was boosted by a $450,000 donation from the National Pork Board.

“Our board met just before the World Pork Expo. We presented to them a pretty detailed plan of attack as far as research needs and research priorities for PEDV. We presented that information, and they voted to release $410,000 for coordinated research efforts and for coordination of the survey,” said Lisa Becton, director of swine health and research for the National Pork Board.

“In addition, our swine health committee had about $40,000 remaining from our spring general call for other diseases that they have allocated toward this effort.”