Scientific American: U.S. Pig Farms May Be 'Flu Factories'

Enlarge this image toggle caption Matthias Rietschel/APN Matthias Rietschel/APN

Last year's H1N1 pandemic was a wake-up call to many scientists to how unpredictable and dangerous viruses circulating in the animal world can be if they jump to humans. The outbreak of avian flu in 2006 was our first clue.

Since then, there's been a lot of talk about monitoring the health of the animals most likely to pass on a flu virus with pandemic potential -- pigs and birds.

But an article just published in Scientific American says our pig monitoring is pretty bad. So bad that American pigs farms are virtually "flu factories," according to author Helen Branswell, a Nieman Fellow in global health reporting at Harvard University.

Why is monitoring so slack? The problem, Branswell writes, is that the pork industry is reluctant to share data with human health officials. And, Branswell says that industry results of pig flu tests are kept confidential.

An official from the Centers for Disease Control and Prevention tells Branswell that every so often, CDC will get a call when someone catches swine flu directly from a pig. But, usually, it's too late for CDC to investigate. The pigs "had often gone off to slaughter by the time we were able to figure out what the exposure actually was," the official tells Branswell.

H1N1, of course, wasn't a pure swine flu -- it had two genes from flu viruses that normally circulate in pigs as well as bird flu and human flu genes. But pigs (and birds) remain the species most likely to host new pandemic viruses.

Scientists, especially in Asia, have gotten a lot better at monitoring birds, but know far less about viruses that infect the nearly one billion domesticated pigs around the world. And about 12 years ago, those viruses began evolving and recombining into new forms that could sicken humans much faster than before, making monitoring a bigger priority.

Earlier this year, the CDC and U.S. Department of Agriculture finally got serious about a surveillance system for pigs they've been discussing for years. But the program requires the support of pork producers. And they "have to date been reluctant to support what many see as a bid by government to meddle in their affairs," Branswell says.

Shots called up the National Pork Producers Council to get the industry's take on the program. Spokesman Dave Warner acknowledged that some producers may be averse to reporting sick pigs because they're afraid that the government will quarantine them.

Still, NPPC officials say they are advocates of the USDA-CDC pig surveillance program. And they say many producers are already submitting blood samples of their pigs to the government for analysis.

Even if we can get a handle on surveillance in the U.S. sometime soon, the next H1N1 could just as easily come from another country, like China, which produces nearly half of the world's pigs, and is doing even less surveillance.