Nathan Weber for The New York Times
A swine virus appeared in the United States last spring in Ohio and in weeks had spread to four more states. How it entered the country is unknown.
By STEVEN YACCINO
Published: August 4, 2013
ANNAWAN, Ill. — The outside world is not allowed in a sanitized and isolated pig farm here, not far from the Iowa border.
Nathan Weber for The New York Times
Jan Hueber, president of Great Plains Management, which stresses strict preventive protocols.
Visitors must shower before entering, scrubbing from head to toe, trading their street clothes for disinfected coveralls that have never left the premises. Everything inside the temperature-controlled barn housing 3,000 sows has been blasted with antiseptic.
“We do a better job than some hospitals,” said Dr. Matt Ackerman, a veterinarian who works with the farm.
Strict protocols have kept the operation, one of 10 swine facilities run by Great Plains Management, safe from a virus spreading across the country this summer, killing piglets by the thousands and distressing hog producers in 16 states.
But those same precautions have not worked everywhere. A Central Indiana farm that Dr. Ackerman also works with was among the first to lose piglets to the virus in May. “If it gets in, you can’t stop it,” Dr. Ackerman said. “We filled wheelbarrows with dead pigs.”
The porcine epidemic diarrhea virus, which is deadly only to young pigs and poses no food safety risks or danger to humans, appeared in the United States for the first time last spring in Ohio and within weeks had spread to four other states.
The outbreak led to a flurry of lab testing and a survey of the industry to determine how the virus had entered the country, comparing supplies and feeds in an effort to find a smoking gun. Farmers are cross-referencing vaccine and semen distributors, even the brands of plastic pipettes they use to inseminate sows, desperate to contain a threat that has made the industry feel increasingly vulnerable.
“It’s anybody’s guess at this point,” said Lisa Becton, director of swine health information and research at the National Pork Board, which is spending $800,000 for research into the virus.
First surfacing in Britain more than 40 years ago, the virus has spread throughout Europe and Asia. It has caused problems most recently among pork producers in China, where a 2012 strand of the disease was 99.4 percent similar to cases now found in the United States, according to researchers.
Researchers in the United States are working on a vaccine for the virus, which is passed through fecal matter and resembles transmissible gastroenteritis, another pig-to-pig illness that American farms have at times encountered. Symptoms include severe diarrhea and vomiting, and mortality rates can reach 100 percent for pigs less than a week old. Older swine will be sick for days but most likely recover.
Retroactive testing by a national laboratory pegged the earliest confirmed case of the virus in the United States around April 15 at a farm in Ohio. Within a month, other cases had surfaced in Indiana, Iowa, Colorado and Minnesota.
By the end of July, 403 separate cases had been reported to the National Animal Health Laboratory Network of the Department of Agriculture, with most outbreaks occurring in Iowa (149) and Oklahoma (94). About 30 new cases are reported each week.
“There’s not many times that a new virus hits an industry that has no immunity,” said Robert Morrison, a professor of veterinary medicine at the University of Minnesota who has been studying the virus. “Every pig in the United States is susceptible. It’s like throwing a spark on a bunch of kindling.”
No one quite knows how many pigs have died so far, in part because the virus is not considered a foreign animal disease by the Agriculture Department and farms are not required to report it to the authorities.
Few experts are willing to speculate, saying only that industry losses amount to several hundred thousand piglets nationwide.
Though it is perhaps too soon to predict how the virus may affect the price of pork products, the epidemic has already caused economic hardships for individual farmers, particularly amid soaring feed prices caused by last year’s drought.
An average farm with 2,500 sows could lose nearly every newborn for four weeks if it is hit with the virus, killing roughly 5,000 piglets and causing financial losses close to $200,000. Adult pigs that recuperate typically build immunity to the virus, making recurring outbreaks rare.
“One month can do a lot of damage,” said Mark Greenwood, senior vice president for AgStar Financial Services, which provides financing to hog farms. “It’s really devastating if you’re finally turning the corner.”
The fear has inspired a renewed vigilance across the hog industry to ensure that workers are using basic practices like disinfecting their boots and trailers after visiting packing plants, which researchers have identified as high-risk locations for picking up the virus.
Yet questions remain about how the virus got to the United States in the first place, raising anxiety among producers and farmers.
“The world got a lot smaller that day,” Tom Burkgren, executive director of the American Association of Swine Veterinarians, said of when the first domestic case was confirmed. “If P.E.D.V. can get into the United States, what about some of the even more nasty viruses?”
Preliminary results from a targeted survey led by the association, which some had hoped would identify a link among infected farms, suggested that more data was needed. Dr. Burkgren said investigators would take a closer look at feed-related risk factors.
Jan Hueber, co-owner of Great Plains Management, the swine consultants, said he would take nothing for granted.
After an Indiana farm he works with lost at least three weeks of piglets from the virus, Mr. Hueber’s truck drivers now wear plastic disposable boots every time they visit a hog facility.
“Do we sleep comfortable at night?” he asked. “Not when you have something looming out there that can be so financially devastating.”
“We assume everything is infected,” he added.
A version of this article appeared in print on August 5, 2013, on page A9 of the New York edition with the headline: Hog Producers Battling to Contain Virus That Has Killed Piglets by the Thousands.