Bacon, Lettuce, and What?

Nicholas D. Kristof, "Our Pigs, Our Food, Our Health"

One of the first clues that pigs could infect people with MRSA came in the Netherlands in 2004, when a young woman tested positive for a new strain of MRSA, called ST398. The family lived on a farm, so public health authorities swept in — and found that three family members, three co-workers and 8 of 10 pigs tested all carried MRSA.

Since then, that strain of MRSA has spread rapidly through the Netherlands — especially in swine-producing areas. A small Dutch study found pig farmers there were 760 times more likely than the general population to carry MRSA (without necessarily showing symptoms), and Scientific American reports that this strain of MRSA has turned up in 12 percent of Dutch retail pork samples.

Now this same strain of MRSA has also been found in the United States. A new study by Tara Smith, a University of Iowa epidemiologist, found that 45 percent of pig farmers she sampled carried MRSA, as did 49 percent of the hogs tested.