As swine flu fears sweep the world, governments everywhere are taking steps to prepare for a global pandemic, such as ramping up disease surveillance, reinforcing medicine stockpiles, and distributing infection control information to citizens. Egypt, however, with no confirmed cases of swine flu within its borders, added another step: Killing all 300,000 of its pigs.

"It has been decided to immediately start slaughtering all the pigs in Egypt using the full capacity of the country's slaughterhouses," Health Minister Hatem el-Gabaly said earlier this week, according to The Independent. The idea is to prevent the animals from passing the disease to humans.

But will such a move actually help? Not in the slightest, says Barbara Straw, a professor of large animal clinical science at Michigan State University's College of Veterinary Medicine in East Lansing: "It doesn't make any sense to kill pigs."

That's because there's no evidence that the flu strain that has caused illness in people in Mexico and 10 other countries is also infecting pigs, says Straw. And if the pigs don't harbor the virus, they cannot pass it to people, Straw adds.

But wait, isn't this swine flu, well, from swine? Actually, not really, says Arnon Shimshony, Israel's former chief veterinary officer. The reason swine flu has its name is that certain parts of its DNA resemble those found in flu viruses that commonly affect pigs, he explains. At some point in the virus's evolution, it probably passed through pigs, which could act like "mixing vessels" of human and avian flu viruses, Shimshony says. (This unusual susceptibility to flu viruses from other species is made possible by receptors on cells in the pig's respiratory tract, he says).

The virus may have a swine history, but it no longer affects swine, he says: "It has become a human problem, a pure human problem." So Shimshony doesn't think killing pigs makes any sense either. The only scenario in which pig-culling would be justified, Shimshony says, is if the particular strain causing the human epidemic began appearing in pigs.

All of this begs the question: Is "swine flu" a misnomer? Apparently the World Health Organization (WHO) and the Obama administration think so; both have begun referring to the virus as H1N1, partly out of fear that the appellation "swine flu" is harming the pork industry.

Still, we should note that there is precedent for influenza viruses to be capable of infecting two different species, although it's rare. A notable exception is avian flu, which can pass from birds to humans, so poultry culling, which has been ordered in Egypt, Hong Kong and other countries plagued by avian flu is prudent, MSU's Straw says. Egypt has had 67 cases of avian flu, 23 of them fatal, since 2006.

So if Egypt culls all these pigs, what happens to the pork? As we noted in our first post on swine flu, there is no evidence that eating bacon, pork chops, or other swine products can cause H1N1 infections, so it should be safe to eat. But assuming most of Egypt's Muslim majority is observant, only about 10 percent of the population—the Coptic Christian minority—is likely to eat it.

See our In-Depth Report for more on the swine flu outbreak.

Image of a piglet (from an unspecified country): be_khe via flickr