Reply #25: yes and no....

[mike_c]

As you suggest, raising pigs in dense and unsanitary conditions certainly fosters disease-- this is evidenced by the routine use of antibiotics in animal feed. But it's important to remember that the REAL culprit here is the adaptability of influenza A virus combined with host similarity between humans and pigs. Swine are a natural incubator for human flu strains, so non-human strains can easily recombine with human-infectious strains in pigs.