opinion

Factory farms are hotbeds for viruses

In Iowa, poultry producers are losing birds due to the latest avian influenza (H5N2) outbreaks on factory farms. The poultry industry nationally has already lost tens of millions of dollars. Since the government compensates producers for birds who are killed to prevent the flu from spreading, taxpayer dollars, as well as animal lives, are being squandered.

The largest outbreak of bird flu in American history was an H5N2 virus, which led to the deaths of 17 million domestic birds and cost the nation more than $400 million during an outbreak in Pennsylvania that started in 1983. In 2002, the first case of human infection with an avian influenza virus was reported. The emergence and spread of virulent strains of avian influenza has been attributed by experts to the intensely overcrowded, unsanitary, and stressful conditions that often characterize large-scale factory farming in industrialized agriculture.

In nature, disease-causing strains of avian influenza rarely spread far because the birds sicken and die before they can fly to spread it to others. However, in unnatural, intensive agricultural systems, pathogens are more easily able to evolve from mild strains to dangerous, highly pathogenic forms. Nine out of 10 chickens used for egg production in the U.S. are confined in barren wire cages. These cages are stacked in often windowless sheds that typically confine more than 100,000 animals each.

Due to the extreme confinement, hens — who are highly intelligent and social animals — cannot engage in natural behaviors like nesting, perching, or even spreading their wings. High levels of stress can lead to weakened immunity, rendering animals much more susceptible to disease. This makes the average poultry factory farm a hotbed for outbreaks of avian flu.

Overcrowding vast numbers of animals beak-to-beak in their own waste presents threats to human and animal health. The poultry industry looks for easy scapegoats such as wild ducks and geese, even though these animals have flown over North America for millennia. Until our society demands hygienic and animal welfare reforms, dangerous pathogens will continue to multiply and spread. The best-case scenario is that these outbreaks will continue to squander taxpayer money on endless games of Whack-a-Mole. The worst-case scenario — the jump of a highly contagious strain to humans — is unfathomable.

MICHAEL GREGER, M.D., is the author of "Bird Flu: A Virus of Our Own Hatching" and the director of public health and animal agriculture at The Humane Society of the United States. Contact: mgreger@humanesociety.org