Our guest blogger is Aysha Akhtar MD, MPH, a fellow for the Oxford Center for Animal Ethics and a neurologist and public health specialist at the Food and Drug Administration.
In order to better avert the threat of swine flu epidemics like the one currently spreading around the globe, public health efforts must address the conditions that allow pigs to become breeding grounds for infectious disease. As the number of confirmed cases of swine flu around the globe increases, we grow closer and closer to having a pandemic on our hands. Surprisingly, however, there is very little discussion about how swine flu got started in the first place.
The primary reservoir for influenza viruses is aquatic birds, but humans are not readily directly infected by the strains from those animals. Pigs, however, are highly susceptible to both avian and human influenza A viruses. In pigs, viruses swap genes, and new influenza strains emerge with the potential to infect humans. The current swine influenza A, called H1N1, is a triple hybrid avian/pig/human virus, “definitely” of swine origin.
More focus needs to be placed on preventing pathogens from getting into the human population in the first place, and that means starting at the farm. The source of the current epidemic has not yet been identified, but the first confirmed case of swine flu occurred in La Gloria, Mexico, a town surrounded by industrial pig farms, partly owned by Smithfields Foods. Even if these particular farms are not confirmed as the primary source, based on research into the previous outbreaks of swine flu, it makes sense to consider factory farms as very likely potential sites for the development of these pathogens.
In recent years the influenza virus has undergone an “evolutionary surge,” with new variants emerging rapidly. According to the World Health Organization, we are seeing more new infectious diseases and epidemics than ever before, and they are appearing at an alarming rate. Increased human travel is certainly a factor, but perhaps the most significant variable is the change in animal agricultural practices that have occurred in the last few decades:
– By 2020, world meat production is expected to double.
– The percentage of operations in North America with 5,000 or more animals expanded from 18 percent in 1993 to 53 percent in 2002.
As a result of the rise in animal product demand, traditional farming practices have been mostly replaced in developed countries by immense intensive animal operations, and developing countries are rapidly catching up.
Increasingly, thousands of animals are confined in these operations, often crowded into sheds. The crowding leads to stressful and profoundly unhygienic conditions. Animals continuously inhale and recirculate aerosolized fecal matter, methane, and ammonia. The wastes and fumes emanating from these intensive operations are so concentrated that nearby human communities commonly have substantial increases in respiratory illnesses such as asthma. The combination of reduced immunity due to prolonged stress in the pigs and the high-density confinement render these operations perfect breeding grounds for new pathogens. Under these conditions, new strains of swine flu are rapidly generated and transmitted from one pig to another by the respiratory route.
In 1998, 2,400 pigs in a North Carolina operation were sickened by a strain of swine flu not seen before. Since that time numerous new flu viruses have emerged and have swept across pig operations throughout North America. WHO and other organizations cite intensive pig farming and other animal factory operations as a significant contributing factor to zoonotic pathogens. Because of the high infectious disease rates in these operations, farm animals are given a constant influx of antibiotics and vaccinations, exacerbating the problem by selecting for drug-resistant bacteria and new, vaccine-resistant viruses.
The high-density intensive animal operations need to go. Not only are they hotbeds for pathogens, but they are also environmentally unsustainable and cruel to the animals involved. The American Public Health Association, recognizing the adverse public health consequences of these intensive farms, has called for a moratorium. That’s a great step in the right direction, but it is not enough. To reduce the supply, the demand for animal products must decrease. We need to address the root of the problem: the intensive farm animal operations and our own appetites.
Read more in the extended version of this post at Science Progress. The opinions expressed here are those of the author and do not represent the official position of the U.S. Food and Drug Administration or the U.S. government.