We know that indiscriminate feeding of antibiotics to livestock has led to higher rates of human infection by antibiotic-resistant bacteria. But how might factory-farming practices increase the threat from the influenza virus?
Michael Greger, M.D., director of public health and animal agriculture for The Humane Society of the United States, listed on the Society's website some of the reasons that "Factory farms can be considered viral breeding grounds." Quoting Dr. Greger, they are: (1)
* The sheer number of confined animals: With so many animals--stressed, deprived and suffering from poor welfare--overcrowded in today's factory farms, a pathogen can run rampant and mutate among so many confined "hosts." As Johns Hopkins School of Public Health Professor Ellen Silbergeld put it: "Instead of a virus only having one spin of the roulette wheel, it has thousands and thousands of spins, for no extra cost. It drives the evolution of new diseases."
* The unnatural stocking density: Swine flu is transmitted like human flu, via infected nasal secretions and respiratory droplets. So, when pigs are intensively confined on factory farms, the large viral loads considered necessary for the emergence of rare flu mutants can rapidly transfer from animal to animal.
* The stress crippling their immune systems: Breeding sows confined in gestation crates can't even turn around and their health can suffer immensely. According to veterinary scientists, crowding more pigs per pen "allows more opportunities for direct nose-to-nose contact or for aerosol spread of the [swine flu] virus between pen mates. Furthermore, a large number of pigs per pen creates physiological stress, which in turn can alter the immune system and predispose pigs to infection."
* The lack of adequate fresh air: The dankness helps keep the virus alive.
* The decaying fecal waste: The millions of gallons of excrement produced by a typical operation decompose and release ammonia, burning the pigs' respiratory tracts, which may predispose them to respiratory infection in the first place.
* The lack of adequate sunlight: In factory farms, there may be no sunlight. The UV rays in sunlight are quite effective in destroying the influenza virus. Thirty minutes in direct sunlight completely inactivates the flu virus, but it can last for days in the shade, and weeks in moist manure.
* Pharmacological crutches: Just as the US pork industry jeopardizes the public through the mass feeding of human...