\n\n“\u201cFactory farms are the best way to select for the most dangerous pathogens possible,\u201d said Rob Wallace, an evolutionary biologist at the Agroecology and Rural Economics Research Corps in St. Paul, Minnesota. To explain why, he offered a crash course in zoonotic transmission, from the point of view of the pathogen.<\/p>\n\n\n\n
\u201cIf you\u2019re a pathogen in a host,\u201d Wallace said, \u201cyou don\u2019t want to kill your host too fast before you can get into the next host \u2014 otherwise you\u2019re cutting off your own line of transmission. So there\u2019s a cap on how much of a badass you can be. The faster you replicate, the more likely you end up killing your host before the next host can come along.\u201d<\/p>\n\n\n\n
If you\u2019re deep in the wildernessor on a small farm, you (the pathogen) are not going to regularly come across hosts, so you\u2019ve got to keep your virulence, or harm inflicted on the host, pretty low so that you don\u2019t run out of hosts. \u201cBut if you get into a barn with 15,000 turkeys or 250,000 layer chickens, you can just burn right through,\u201d Wallace said. \u201cThere\u2019s no cap on your being a badass.\u201d<\/p>\n\n\n\n
This is part of why factory farms are a bigger risk for zoonotic outbreaks than the natural world or small farms.<\/p>\n\n\n\n
The biologist added that because we\u2019re increasingly trading poultry and livestock across international borders, we\u2019re ramping up the danger even more. Strains that were previously isolated from each other on opposite sides of the world can now recombine.<\/p>\n\n\n\n
\u201cTake influenza,\u201d Wallace said. \u201cIt has a segmented genome, so it trades its genomic parts like card players on a Saturday night. Usually, most hands are not too terrible, but some hands come out much more dangerous. An increase in the rate of recombination means an explosion in terms of the diversity of pathogens that are evolving.\u201d<\/p>\n\n\n\n
The world has already seen a really frightening example of this. Between 1997 and 2006, highly pathogenic strains of H5N1 bird flu were linked to poultry farms in China.<\/p>\n\n\n\n
\u201cOur entire understanding of how bad a pandemic could potentially be changed in 1997 with the emergence of the H5N1 avian influenza virus. All of a sudden, there was a flu virus that was killing over half the people it infected,\u201d Greger said.<\/p>\n\n\n\n
When people became infected with H5N1, it had a 60 percent mortality rate<\/a>. For comparison, experts<\/a> estimate<\/a> that Covid-19\u2019s mortality rate is probably somewhere in the neighborhood of 1 percent to 3 percent, though these estimates continue to evolve and vary widely by country and by age<\/a>. (If you\u2019re wondering why H5N1 didn\u2019t become as big a deal as Covid-19, it\u2019s because it mostly infected poultry rather than people; it wasn\u2019t as good at infecting humans as the coronavirus unfortunately is.)”<\/p>\n\n\n\n …<\/p>\n\n\n\n “The other pandemic risk associated with factory farms has to do with \u201chighly drug-resistant forms of bacterial pathogens,\u201d as Shah put it \u2014 that is, antibiotic resistance.<\/p>\n\n\n\n When a new antibiotic is introduced, it can have great, even life-saving results \u2014 for a while. But as we start to use and overuse antibiotics in the treatment of humans, crops, and animals, the bacteria evolve, with those that have a mutation to survive the antibiotic becoming more dominant. Gradually, the antibiotic becomes less effective, and we\u2019re left with a disease that we can no longer treat.”<\/p>\n\n\n\n …<\/p>\n\n\n\n “\u201cWe have abundant evidence documenting the fact that when you put animals in crowded, unsanitary conditions and use low-dose antibiotics for disease prevention, you set up a perfect incubator for spontaneous mutations in the DNA of the bacteria,\u201d said Robert Lawrence, a professor emeritus of environmental health at John Hopkins University.<\/p>\n\n\n\n \u201cWith more spontaneous mutations,\u201d he explained, \u201cthe odds increase that one of those mutations will provide resistance to the antibiotic that\u2019s present in the environment.\u201d Those resistant bacteria could become strains that spread all over the world. \u201cThat\u2019s the biggest human health risk of factory farms.\u201d”<\/p>\n\n\n\n …<\/p>\n\n\n\n ” factory farming presents us with a double bacterial risk. Say a bacterial outbreak emerges among chickens. The poultry can pass that bacteria on to us humans, causing serious infection. We\u2019d normally then want to use antibiotics to treat that infection, but precisely because we\u2019ve already overused antibiotics on our farmed animals, the bacteria may be resistant to the antibiotic. If the infection happens to be one that transmits well between people, we can end up with an untreatable bacterial pandemic.”<\/p>\n\n\n\n …<\/p>\n\n\n\n “Laborers in meat plants are typically stationed very close together along processing lines, which makes social distancing all but impossible.”<\/p>\n\n\n\n …<\/p>\n\n\n\n “We can absolutely have a meat production system that is better for human health, the climate, and animal welfare \u2014 if we\u2019re willing to abandon factory farming.<\/p>\n\n\n\n \u201cThe de-intensification of the livestock industry would go a long way toward reducing pandemic risk,\u201d Greger said. \u201cI mean decreasing long-distance live animal transport, moving toward a carcass-only trade, and having smaller and less-crowded farms. Basically, the animals could use a little social distancing, too.\u201d”<\/p>\n\n\n\n …<\/p>\n\n\n\n “We also need to reintroduce more biodiversity into our farms. Raising animals that are slightly different from each other genetically (rather than selecting for specific genes) will build in immunological firebreaks to help prevent the spread of infectious diseases”<\/p>\n\n\n\n