Anchor Marco Werman speaks with Ellen Silbergeld, professor of environmental health sciences at Johns Hopkins School of Public Health, about what scientists know so far about the swine flu virus, or "Influenza AH1N1." Some think industrial-size pig farms in Mexico may have played a role in creating the virus.
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MARCO WERMAN: Health officials have begun avoiding the term “swine flu†for the virus that's caused so much trouble in Mexico and elsewhere. The virus is, in fact, a hybrid. It combines genetic elements of swine, bird, and human flu viruses from North America and Eurasia. No one knows where or how this novel virus came to be, but that hasn't stopped people from speculating. Some scientists and public health researchers are looking closely at a large industrial pig farm near where some of the first cases of the disease were reported. There's no direct evidence to suggest that the hog farm was the source of the virus, or even that any hog farm was the source. But it's the kind of thing that researchers are concerned about. Ellen Silbergeld is a professor of Environmental Health Sciences at John Hopkins School of Public Health in Baltimore. She's studied the health implications of industrial livestock production.
ELLEN SILBERGELD: I think we really don't know in terms of specific pig farms. On the other hand, I think we know a good deal about the operation of these kinds of large-scale food animal production facilities. And for many years, there's been a great deal of concern about their potential contribution to the evolution and spread of newly emerging diseases.
WERMAN: So there is a strong suspicion that potentially a large-scale pig farm could have caused or at least contributed to the virus. What is it about the way these pig farms are kind of organized and how big they've gotten that could have contributed to this virus?
SILBERGELD: There are three aspects to this mode of production which have been of concern. One is the large amount of animals that are crowded together in one facility. For pigs, this can be between 2 and 6,000 animals per building.
WERMAN: So “crowded†in short?
SILBERGELD: Crowded. Very crowded. Second, these facilities are not biosecure. Because you have so many animals in one building, it is essential to have very high rate of ventilation, or else these animals will die of heatstroke. Because of that simple reason, there's ample opportunity for pathogens, bacteria, viruses, to enter these buildings and also to escape. And this has been demonstrated in numerous studies around the world by us and other researchers. Part of the lack of security, which in many ways may well be the most worrying aspect of their operation, is the very large volumes of waste that are produced by thousands of animals held in confinement. In most countries in the world, including the United States, there are no regulations in terms of pre-treating this waste before they're used for a variety of purposes such as fertilizer or simply as land disposal. In contrast to what is required for the utilization of human bio-solids which are widely used as fertilizer, but they have to be tested. There are no such requirements for animal waste, which is astounding.
WERMAN: Is it your impression that large-scale pig farms in Mexico are operated any differently from large-scale pig farms in the US?
SILBERGELD: No. I don't believe they are. This pig farm was under contract to Smithfield, which is a multi-national corporation based in the United States. And these corporations which contract with farmers to produce the animals, actually set the conditions under which animals are raised. And thus, I expect this pig farm is probably very similar to ones I have visited in the United States.
WERMAN: And how has Mexico handled this crisis? How would you rate it?
SIBERGELD: From what I can see, I think that the world should be very grateful that this occurred in Mexico.
WERMAN: Why is that?
SIBERGELD: Because of the rapidity of response, the transparency of the transfer of information, and the potential for us really to understand some of the dynamics of something as critical as this. I can think of many places in the world where this would not have happened, would not have unfolded in this way, and the consequences could have been vastly more serious.
WERMAN: Ellen Sibergeld, a Professor of Environmental Health Science, is at Johns Hopkins School of Public Health. Dr. Silbergeld, thank you very much for speaking with us.
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