No one is an island.

The links between agriculture and human health are complex. Anyone who’s read Diamond’s Guns, Germs, and Steel will be familiar with the notion that many devastating diseases – smallpox is perhaps the most obvious – crossed to humans from their livestock. However, those people who lived in close proximity to each other and to their animals eventually developed a degree of resistance.

There is, I think, a powerful tendency to imagine that this interplay between human and non-human is in the past, or at worst, still occurring in some parts of the world (China, Africa), but not North America.

One of my profs has done quite a bit of research into the outbreak of E. Coli O157:H7 in Walkerton, Ontario in 2000, and he would argue that’s certainly not the case. In a paper on the topic, Ali (2004) noted research that suggests that the virulence of that particular strain of E. Coli appears to be at least partly due to its ability to survive extreme environments, including the highly acidic environment of the stomach, and it may have acquired this ability through exposure to acidified soil and water. The acidic soil and water, of course, was the result of acid rain, caused by human activities which emitted sulfur dioxide into the air. Ali (2004) also stressed the fact that while the virulent strain of E. Coli is believed to have emerged first in Argentina, it is now widespread across North America. The human role in the transmission of the disease is better understood than our role in its creation. Many people have pointed out that E. Coli O157:H7 is particularly dangerous because it can survive high heat and freezing, and so poses a risk to anyone who buys meat which is contaminated; Walkerton also proved that a breakdown in the containment systems of intensive livestock operations or a breakdown in a water utility can put people at risk of illness or death.

With all of this in mind, it was interesting to read Nicholas Kristof’s column in The New York Times today:

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.

MRSA is methicillin-resistant Staphylococcus aureus, a disease which I at least have always thought of as a disease one is most likely to contract in hospital. Kristof’s article suggests that assumption is a dangerous one. Even if one cannot contract MRSA by eating pork, which is likely as it is typically transmitted by skin contact, many people work in the livestock industry. They can transmit the disease to each other and to their families and friends as well as contract it from contact with their animals. They might also spread it to healthy animals, and in today’s agricultural system, livestock may be sold and transported across a distance, further increasing the number of potential infections.

Kristof’s story is not finished:

So what’s going on here, and where do these antibiotic-resistant infections come from? Probably from the routine use — make that the insane overuse — of antibiotics in livestock feed. This is a system that may help breed virulent “superbugs” that pose a public health threat to us all. That’ll be the focus of my next column, on Sunday.

And his story is raising old questions about the safety of antibiotic use in agriculture. But it’s one that needs to be asked continuously, because we have not yet addressed the potential harms of the way we raise crops and livestock. I don’t think anyone can deny the raise them – we too will be affected.at more food is available at lower cost – at least in North America – than in the past, but there are also unintended consequences, and we cannot escape them.

We need to remember that although we no longer share close quarters with the animals we raise for food, we are still embedded in the same, increasingly complex, ecosystem that they are. When those animals are afflicted by disease – partly because of how we raise them – we too are affected. Until we recognize this in our food policies, this will continue.

Ali, S. Harris. (2004) “A Socio-Ecological Autopsy of the E. coli O157:H7 Outbreak in  Walkerton, Ontario, Canada.” Social Science and Medicine 58(12): 2601-2612

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