In researching my upcoming book on factory farming for St. Martins Press, I have come across many warnings from our past about the looming threat of pandemic influenza emerging from large-scale hog operations.
It now appears that six of the eight genetic components in the currently circulating virus are direct descendants of a swine flu virus that first emerged in North Carolina a decade ago. That bug was discovered in August 1998, at a 2,400-head breeding facility in Newton Grove, NC, where all the sows suddenly came down with a phlegmatic cough. Pregnant animals spontaneously aborted their litters.
Nasal swabs from the pigs were sent to the state agriculture department's Animal Disease Diagnostic Lab in Raleigh. State scientists at first did not think the outbreak was extraordinary. To them, it sounded like another case of "classic" swine flu, which had appeared many times before in North Carolina. That virus is also known to cause fevers and miscarriages in sows.
But when scientists ran the regular tests for swine flu, they were stumped. They simply did not recognize the virus they were looking at. Even more alarming, some of the sows who got sick had been vaccinated against classic swine flu. That vaccine had clearly failed to stop this particular infection.
(All of the pigs at Smithfield's facility in Mexico were also reportedly vaccinated against swine flu, but not against the current strain - and we now know that it was recently transmitted from a farmer to his pigs in Alberta, Canada).
By the end of 1998, the new bug had also acquired two bird flu gene segments as well, evolving into a previously unseen "triple reassortment" virus, a worrisome and unprecedented monster of human, hog and bird flu origin.
Fortunately for us, back in 1999, the new flu virus did not become a threat to people - humanity had dodged one big epidemiological bullet. Even so, scientists tried to warn the world that this would happen again, only next time it would bring far more calamitous results.
"It's a wake up call," Dr. Nancy Cox, an influenza expert at the CDC, told the Raleigh News & Observer at the time. "It showed a human flu strain has gotten into pigs and that strain may permanently establish itself in pigs," she said. "It can go both ways. You have veterinary consequences as well as human consequences of this interspecies transmission."
And the prestigious journal Science pronounced that, "After years of stability, the North American swine flu virus had jumped on an evolutionary fast track."
Even a decade ago, the planet was already well overdue for a global human pandemic, warned one of the top virologists in the world, Dr. Robert Webster, at St. Jude's Children's Research Hospital in Memphis. He said that children, teenagers and young adults born after the 1968 Asian flu pandemic would be especially vulnerable, because they would have no immunity to a reconstituted Asian flu virus.
Interestingly, nearly all the deaths in the current pandemic have occurred in people born after 1968, something that should probably be investigated.
And even though the feared leap to humans did not materialize (10% of US hog workers tested did show antibodies to the 1998 triple-assortment virus, but none had gotten sick) North Carolina's chief epidemiologist cautioned that the new virus could still jump back and forth between pigs and people.
"We don't know how often these reassortments occur in nature - probably more than we want to realize," agreed Dr. Newton MacCormack, chief of communicable disease control at the NC health department. "We're pretty lucky that most of these viruses reach a genetic dead end. The big problem is the rare occasion when one of these viruses gets into a human and begins to be passed from person to person."
The 1998 outbreak, though confined to pigs, spread with ferocious virulence. Soon after the North Carolina sows got sick, outbreaks were reported in Texas, Minnesota, and Iowa herds. Within months, pigs were getting sick nationwide. More than 4,300 samples were taken from swine in 23 states, and on average, 20.5% of them had the new triple-assortment virus. In Illinois and Iowa, 100% of the animals were infected, while Kansas and Oklahoma each reported rates of 90%. The long-distance transport of live animals - from farrowing to fattening to slaughtering - was blamed for the rapid dissemination.
Fortunately, back then the North Carolina agriculture department introduced new diagnostic tests that were advanced enough to identify emerging "reassortments" of novel viruses mixing human and animal components. Such vigilance, it was thought, would help prevent a similar outbreak in the future.
"These influenza viruses can shuffle like a deck of cards, but we will at least have one more diagnostic tool in our hands when this happens again," Dr. Gene Erickson, director of microbiological testing at the state agricultural lab, told the N&O. "That might give us some extra time when there is a true outbreak of a new virus."
Erickson added that "the best way to view this whole series of events would be as a valuable learning experience for all of us. We will be much better prepared should it happen again."
Ten years later, a new and deadly outbreak of swine flu would appear in people, most likely beginning in Mexico, and then spreading around the world - even before it was isolated and identified in a lab. The Mexican government apparently was not equipped with the same testing equipment that Dr. Erickson had installed in Raleigh.
We still don't know where the current virus emerged, ("pig zero," as some have called it). But we may one day learn that, if proper scientific monitoring of emerging viruses had been in place, a global pandemic might have been averted.
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