In 2005, the United Nations said that governments, local authorities, and international agencies "need to take a greatly increased role in combating the role of factory farming" which, they added, "provide[s] ideal conditions for the [influenza] virus to spread and mutate into a more dangerous form." In other words, these factory farms can be thought of as the original incubators of dangerous strains of the flu.
My colleague Michael Greger, M.D.-author of Bird Flu: A Virus of Our Own Hatching-calls factory farms breeding grounds for diseases: vast numbers of animals with immune systems weakened by unyielding stress, their lungs burning from ammonia emitted by decomposing excrement, and a lack of fresh air or sunlight. Put all these factors together and what you have is a perfect-storm environment for the emergence and spread of new "superstrains" of influenza. I encourage you to read Dr. Greger's op-ed on this flu outbreak in the Des Moines Register this week.
Let's take this current bird flu outbreak as an opportunity to stop and think whether we really want to continue allowing the poultry industry to operate in this way, exploiting immune-compromised and genetically-weakened animals and creating breeding grounds for disease that pose huge threats to humans and birds alike.