Oklahoma winds may spread deadly swine virus

Since June, when PEDv first hit, workers have quarantined the area, 
scrubbed vehicles and sprayed buildings with antiseptic

Reuters / On the windswept prairies of the Oklahoma Panhandle, the hog barns of Prestage Farms are lined up like military barracks. The 20,000-sow operation near the Texas border stands at the front lines of a months-long battle to contain a virus that has already killed some 1.3 million hogs in the United States.

Since June, when Porcine Epidemic Diarrhea virus, or PEDv, first hit, Prestage workers have quarantined the area, scrubbed vehicles and sprayed buildings with antiseptic. But those precautions have not stopped a virus that can kill 80 per cent of piglets that contract it.

“In the blink of an eye, 30,000 pigs were dead,” said John Prestage, senior vice-president at Prestage, describing the first wave of devastation the virus brought to its Oklahoma operation, which raises and sells 400,000 hogs a year.

The outbreak is spreading. And researchers have discovered evidence that the virus — which poses no threat to humans — can be carried on the wind, potentially bringing a dangerous new dimension to the swine epidemic.

More than 600 cases, each of which could represent thousands of infected animals, have been reported in 17 states. If research confirms that the disease can be transmitted through the air, it would heighten concern about controlling the outbreak.

Mystery

Mystery surrounds the virus, which first cropped up in Europe in the 1970s and remains uncontrolled in China and other parts of Asia nearly four decades after it first appeared. In the U.S., which discovered its first-ever case in April, the outbreak of the heat-sensitive virus slowed this summer as temperatures rose and weakened the spread. But PEDv is expected to thrive again as the weather cools, and airborne transmission could further the virus’s reach.

Previously, scientists had found the swine virus was transmitted only by physical contact, or carried in on dirty boots or contaminated equipment. But new research shows the virus can be carried through the air on dried fecal matter, even though scientists say the virus has not mutated. The strain making its way across the nation’s hog farms and slaughterhouses is 99.4 per cent similar in genetic structure to the PEDv that hit China’s herds last year, according to the U.S. researchers.

Indeed, farmers and pork processors in Oklahoma have told Reuters they now suspect the virus is traveling through the air.

One scientist likened this to the way the deadly Avian influenza has travelled on feathers and fecal dust. That influenza virus has so far killed poultry by the millions and more than 300 people in 13 countries, according to World Health Organization data.

“There is a chance that airborne contaminated feces may have played a role in the rapid dissemination” of the virus, particularly in Oklahoma, said Dr. Montserrat Torremorell, who is leading research efforts on the outbreak at the University of Minnesota’s College of Veterinary Medicine.

Researchers at Minnesota’s veterinary diagnostic lab found the virus in air samples taken by Seaboard Foods, a large pork producer, from the vicinity of its Panhandle hog farms and its packing plant near Guymon, Oklahoma.

Pigs injected with samples of the virus collected by Seaboard Foods did not contract the disease, Torremorell said. But she still believes airborne distribution may be a threat. “I would not rule it out,” she said.

Death toll

Federal investigators have not pinpointed the origin of the coronavirus that causes PEDv or how it entered the United States. Farmers, veterinarians and laboratory researchers have offered theories ranging from vaccine suppliers to vitamin mix distributors to the pipettes used to inseminate sows.

All agree PEDv’s mortality rate is astounding: between 80 per cent to 100 per cent of very young animals. Most of these piglets die within 72 hours from dehydration associated with diarrhea. Older animals usually survive after being ill.

Officials from the Agriculture Department say they cannot offer a sound estimate on mortality rates, as farmers are not required to report to authorities when there is a PEDv outbreak on their operations.

Eric Neumann, a swine epidemiology expert at Massey University EpiCentre in New Zealand, told Reuters he used data released by federal investigators, and has pegged the death toll at 1.3 million pigs and climbing.

As of the week of Sept. 8, there had been 612 confirmed cases reported in 17 states, according to federal officials. Iowa, the largest U.S. hog producer with 20 million hogs, had reported 181 cases, the most of any state. Oklahoma was second with 155, and Kansas had 77 reported cases.

Researchers are closely watching North Carolina, the nation’s second-largest hog state, where 40 cases had been reported since the week of June 23.

To combat the disease, farmers are taking precautions in their handling of animals. Hog producers that use the manure on their own crop fields are searching for ways to get rid of the PEDv, while some grain farmers are hunting for PEDv-free manure for their spring planting.

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