Swine Flu in Swine: Flu Could Worsen; Industry at Risk

October 14, 2009

The United States pork industry has already been battered by the false perception that pork can transmit swine flu. And now farmers are bracing for the first reported transmission of the virus to a U.S. pig, which at this point seems inevitable, experts say.

Beyond the economic impact, experts warn that, if transmitted to pigs, swine flu could quickly mutate into a more dangerous strain, given the crowded conditions at many industrial hog farms. (Related: "Swine Flu Facts, Swine Flu Myths.")

Officially called H1N1, the new swine flu virus is widely believed to have formed from other strains in pigs. It is already known to be present in pig herds in Canada, Argentina, and Australia. It has not yet been reported among pigs in the U.S.

"But we expect it to get here," said Rodney Baker, a swine veterinarian at Iowa State University. The most likely cause will be a swine flu-infected employee, he said.

"We know pork is safe from influenza viruses, but still the public perception and the news media have really had a circus with this thing," Baker said. "And so we are pretty paranoid about destroying our industry with this virus even though it is not a true concern."

(Related gallery: "Swine Flu Pictures: Bracing for a Potential Pandemic.")

Swine Flu Softer on Swine?

Flu germs pass from human to pig and from pig to pig the same ways germs pass from person to person—sneezes, coughs, and runny noses.

"Pigs sneeze and cough a lot [when infected] with most viruses," noted Baker, who is also president of the American Association of Swine Veterinarians.

But compared to humans, swine don't seem quite as bothered by the virus that bears their name, he said.

Pigs given the swine flu virus by researchers with the U.S. Department of Agriculture coughed and lay down for about 48 hours with no desire to eat, Baker said. "Then they recovered quickly. In fact, pigs appear to recover faster than humans do from influenza."

Swine Flu Mutation

Once in the pigs, though, the swine flu virus could combine with other viruses and reemerge in the human population as a more virulent strain, scientists and industry observers worry.

"Pigs are a really good petri dish for further mutation of flu viruses," said Robert Martin, a senior officer with the Pew Environment Group in Washington, D.C., who led a 2008 study on industrial animal operations.

Most pigs today are raised in so-called confined animal feeding operations, which pack thousands of swine into enclosed areas, fattening them up for market.

"The concern is that there are so many animals that the virus can go through several generations of mutation in a very quick period of time," Martin added.

Baker, the swine veterinarian, said human viruses and bird viruses got into pigs several times in the mid to late 1990s, recombined with the pig viruses, and became the dominant pig viruses still around today.

But "we've never had one recombine in the pig and become the new human virus, thus far, unless the current one came direct from a pig to a human."

At some point, the new swine flu outbreak sweeping the globe may have incubated in pigs, perhaps forming from human and bird flu viruses.

"The ancestors of this virus have been found in swine, so probably this virus originated at some point in swine," said Raul Rabadan, a biologist at Columbia University in New York who has studied the strain's origins.

Though Rabadan and other researchers have suggested a swine origin for the current virus, the hog farming industry remains unconvinced.

Baker, the veterinarian, said, "Most of us on the animal side, we scratch our heads and say, Well, maybe not—it might have been turkeys or something."

Protecting Pigs From Swine Flu

To prevent a person-to-pig transmission of the new H1N1 swine flu, the National Pork Producers Council is recommending hog farms tell their sick employees to stay home and, when at work, to wash frequently and wear protective clothing when around the pigs.

Other suggestions include limiting the number of visitors allowed on the farms, monitoring workers who've recently been abroad, keeping a close eye on the pig herds for signs of infection, and, when it's available, encouraging workers to get the upcoming swine flu vaccine.

The U.S. Department of Agriculture has made a so-called "master seed" virus that several pharmaceutical firms are using to make swine flu vaccines for pigs, though they won't be ready until November, Baker said.

When the vaccine is available, the government will not require farmers to use it on their pigs, since meat from swine flu-infected pigs is safe to eat.

"Whether they would need to vaccinate for this novel H1N1 will be directly dependent upon the severity that we see in the human population and whether we start seeing cases in the swine population," said John Clifford, the USDA's chief veterinary officer, during a press briefing in September.

Farmers may choose to vaccinate the animals against flu anyway—a common practice, since sick animals eat less, grow slower, and fetch lower prices, USDA officials told National Geographic News during the briefing.

Given the perception of swine flu's association with swine some producers may want to vaccinate their pigs to protect their brand images, Baker said.

Industry Already Hit by Swine Flu

The hog farming industry has already lost hundreds of millions of dollars since the virus first emerged in humans this April, said Jennifer Greiner, director of science and technology for the National Pork Producers Council in Washington, D.C.

For example, she said, "We never saw the summer rally [in pork prices] this year that we have historically seen" during barbecuing season.

The pork industry has run an aggressive marketing campaign on the safety of pork but fears the message is failing to reach the public.

A well-publicized swine flu outbreak among swine could make matters even worse, Greiner said.

In one scenario, "we would see pork prices go down again and consumers would become fearful that if they ate pork, they would get H1N1," she said. "And we just restart the spiral downward."




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