Some of the pigs in a 5,000-porker Northern Ireland pig farm have been coughing. You'll never guess what the diagnosis is.

Yes, it's swine flu, and health authorities are quickly trying to figure how they became the latest animal victims of the famous virus named after them.

About 4,500 hogs at the "piggery" in Greenhill have come down with the pandemic flu. Five pigs died in the outbreak, which was detected two months ago when the animals stopped behaving like pigs: They lost their appetites.

Veterinary officer Nigel Gibbens told Bloomberg News said no known cases of human flu have been linked with the outbreak, which resembles infections in pigs in Canada, Australia and Argentina.

“What is critically important in this situation is good outbreak investigation to develop a better understanding of how the pigs picked up this virus,” the International Society for Infectious Diseases said. Such a probe “will help determine potential exposures of the pigs and whether this is another instance of the virus traveling from humans, in a reverse fashion, to infect swine.”

It's a real chicken-and-egg problem, so to speak, for researchers. Did pigs infect some humans who then infected some pigs? Which species got it first? Can pigs be treated with Tamiflu? Should they wash their hooves more often, especially after, well, you know...

"Everything that goes around, comes around," was the scientific wisdom offered by a Greenhill pub patron. "I mean, it's swine flu, isn't it? Why shouldn't pigs get it?"

Why indeed?

The new H1N1 flu strain, discovered in Mexico and the U.S. in April, has swept across almost 200 countries in four months. The virus has genetic material from pig, bird and human flu strains. More is of pig origin, prompting the reference to “swine flu.” The World Health Organization is now referring to the virus as the pandemic (H1N1) 2009 virus, according to Bloomberg.

U.S. Agriculture Secretary Tom Vilsack appealed to the media to stop calling the H1N1 virus swine flu, saying the term hurts sales of pork and adds to losses for hog farmers. The H1N1 virus is not transmitted through properly handled pork.