From the 1918 Spanish Flu, to the 2009 Swine flu, influenza A viruses are a proven global pandemic threat. Pig farms are a near perfect breeding ground for influenza A viruses (Neumann et al. 2009). These viruses will likely cause the next global pandemic because of their ability to readily mutate, undergo reassortment and then turn into a more deadly virus infecting humans (Ma et al. 2009a). Factory farms, with a high population density of animals of the same species, are a perfect environment for facilitating mutation in these rapidly changing viruses.
The Spanish Flu infected 1/3 of the world’s population and killed 50 million people and in 2009, Swine flu lead to 300,000 deaths world wide. Molecular analysis shows Swine Flu had been circulating in pig populations for over a decade. It only came to the attention of the public when humans started showing symptoms. Before that, a 2007 review identified 50 cases of zoonotic swine influenza infection reported in the literature between 1958 and 2005 (Myers et al. 2007).
There are almost 700 million pigs worldwide. Pigs represent a significant reservoir of emerging and potential zoonosis. Farm workers, butchers, veterinarians and processing plant workers are at risk of being exposed to and spreading these novel pathogens. These workers already show serological evidence of prior swine influenza infection (Myers et al. 2006, Ramirez et al. 2006, Gray et al. 2007). Like, sars-cov-2, when a novel disease is unleashed upon a naive population, potential pandemics arise. In fact, the next global pandemic may come from a factory farm near you.
References
Stuart-Harris, C, Schild, G, Oxford, J. Influenza: The Virus and the Disease. London: Edward Arnold, 1985.
Gray, GC, McCarthy, T, Capuano, AW, Setterquist, SF, et al. Swine workers and swine influenza virus infections. Emerg Infect Dis 2007; 13:1871–1878.
Ma, W, Lager, KM, Vincent, AL, Janke, BH, et al. The role of swine in the generation of novel influenza viruses. Zoonoses Public Health 2009; 56:326–337.
Myers, KP, Olsen, CW, Gray, GC. Cases of swine influenza in humans: a review of the literature. Clin Infect Dis 2007; 44:1084–1088.
Myers, KP, Olsen, CW, Setterquist, SF, Capuano, AW, et al. Are swine workers in the United States at increased risk of infection with zoonotic influenza virus? Clin Infect Dis 2006; 42:14–20.
Neumann, G, Noda, T, Kawaoka, Y. Emergence and pandemic potential of swine-origin H1N1 influenza virus. Nature 2009; 459:931–939
Ramirez, A, Capuano, AW, Wellman, DA, Lesher, KA, et al. Preventing zoonotic influenza virus infection. Emerg Infect Dis 2006; 12:996–1000.