Over the past few months, eight people in Cambodia have died from a strain of avian flu, H5N1. Six of those people were children. Meanwhile, in Mexico, over 1 million chickens infected with a different strain of the bird flu, H7N5, were destroyed by authorities concerned with the human health risk. This is nothing new. In fact, in 2009, another strain of avian flu, H1N1, quickly became an international pandemic and resulted in more than 14,000 deaths worldwide.
The science and past experience is clear. Avian flu is deadly when contracted by human beings. However, the risk to humans is naturally considered low because the virus rarely jumps the species barrier. In fact, before the H1N1 pandemic, scientists believed that direct or indirect contact with an infected bird was necessary for transmission. Now we know that H1N1 can be transmitted from human to human in the same way as the traditional flu and is considered very contagious.
So how does a flu found in birds that can only be transmitted with direct or indirect contact with an infected bird transform into a highly contagious human transmitted disease? Several studies have shown that extreme confinement of animals at factory farms is the greatest factor in transforming these diseases.
The 2009 H1N1 pandemic was “the product of intensive farming.” Scientists traced the H1N1 virus to a strain of swine flu that had been circulating among large scale pig farms since 1998. This strain of swine flu was first identified on a factory farm in North Carolina. When the virus was discovered, all 2,400 pigs on the farm were infected. The virus quickly spread, infecting several thousand pigs in 23 states.
Pigs are considered ‘mixing vessels’ for influenza because they are susceptible to both avian and human influenza viruses. As a result, swine, avian, and human viruses co-mingle in pigs. This leads to gene swapping and mutation, and the creationof a hybrid influenza virus that can easily spread to humans.
When pigs are desperately crowded in confined operations, the risk of transmission is extremely high. In general, animals raised for food live in filthy and cruel conditions that reduce their ability to fight infections. As a result, if a novel virus appears on a farm, it easily replicates, spreads, and ultimately mutates. This is exactly what happened with the 2009 H1N1 epidemic.
Dr. Robert Webster is one of the world’s leading experts of flu virus evolution. He has called the intensive farming practices in the United States “unsound.” These practices emphasize the profitability of crowding more and more pigs into less space. As a result, most pig farmers in the U.S. now confine more than 5,000 animals on a single farm. The Pew Commission on Industrial Farm Animal Production concluded that industrialized animal agriculture posed “unacceptable” public health risks.” The public health risk associated with these practices led the American Public Health Association in 2003 to call for a moratorium on factory farming.
Yet, even with the knowledge that factory farming practices caused the H1N1 epidemic and the call from well-respected scientists and public health organizations to end these practices, nothing has been done. As a result, a new virus, H5N1, is currently following in the footsteps of H1N1.
A 2010 study confirmed widespread H5N1 infection in factory farm pigs. Interestingly, infected pigs show no symptoms of H5N1. This means that the virus can evade detection and further evolve in pig populations transported throughout the world. In the U.S., factory farmed pigs are bred in one state, fattened on a feed lot in another, and then slaughtered in yet another. The discovery of H5N1 in pigs is just the beginning of the next influenza outbreak. The H5N1 virus has a 60 percent mortality rate in humans. The H1N1 virus that killed over 14,000 people only had a mortality rate of less than 1 percent.
As Dr. Aysha Akhtar explains, “our risk for a deadly form of the ‘bird flu’ virus and other pathogens remains high as long as we don’t improve our treatment of animals.”