H1N1 flu virus link to USA pig industry

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CDC Confirms link to USA pig industry

by Michael Greger, MD

Michael Greger, MD

Michael Greger, MD

Factory farming and long-distance live animal transport apparently led to the emergence of the ancestors of the current swine flu threat.

A preliminary analysis of the H1N1 swine flu virus isolated from human cases in California and Texas reveals that six of the eight viral gene segments arose from North American swine flu strains circulating since 1998, when a new strain was first identified on a factory farm in North Carolina.

This analysis, first released by Columbia University’s Center for Computation Biology, has now been reportedly confirmed by researchers at the University of Edinburgh, St. Jude’s Children’s Research Hospital and virologist Ruben Donis, chief of the molecular virology and vaccines branch at the U.S. Centers for Disease Control and Prevention. Dr. Robert Webster, the director of the U.S. Collaborating Center of the World Health Organization, and considered the “godfather of flu research,”[1] is reported as saying “The triple reassortant in pigs [first discovered in the U.S. in 1998] seems to be the precursor.”

Plaguing People and Pigs

The worst plague in human history was triggered by an H1N1 avian flu virus, which jumped the species barrier from birds to humans[2] and went on to kill as many as 50 to 100 million people in the 1918 flu pandemic.[3] We then passed the virus to pigs, where it has continued to circulate, becoming one of the most common causes of respiratory disease on North American pig farms.[4]

Tracing the Origins of Today’s Virus

Since the progenitor of the swine flu virus currently threatening to trigger a human pandemic has now been identified, it is critical to explore what led to its original emergence and spread. Scientists postulate that a human flu virus may have starting circulating in U.S. pig farms as early as 1995, but “by mutation or simply by obtaining a critical density, caused disease in pigs and began to spread rapidly through swine herds in North America. [emphasis added]”[9] It is therefore likely no coincidence that the virus emerged in North Carolina, the home of the nation’s largest pig production operation. North Carolina has the densest pig population in North America and reportedly boasts more than twice as many corporate pig mega-factories as any other state.[10]

The year of emergence, 1998, was the year North Carolina’s pig population hit ten million, up from two million just six years earlier.[11] Concurrently, the number of pig farms was decreasing, from 15,000 in 1986 to 3,600 in 2000.[12] How can five times more animals be raised on almost five times fewer farms? By crowding about 25 times more pigs into each operation.

In the 1980s, more than 85% of all North Carolina pig farms had fewer than 100 animals. By the end of the 1990s, operations confining more than 1,000 animals controlled about 99% of the state’s pig population.[13] Given that the primary route of swine flu transmission is thought to be the same as human flu—via droplets or aerosols of infected nasal secretions[14]—it’s no wonder experts blame overcrowding for the emergence of new flu virus mutants.

“A Recipe for Disaster”

The European Commission’s agricultural directorate warns that the “concentration of production is giving rise to an increasing risk of disease epidemics.”[26] Concern over epidemic disease is so great that Danish laws have capped the number of pigs per farm and put a ceiling on the total number of pigs allowed to be raised in the country.[27]

No such limit exists in the United States or in Mexico. The fact that the first confirmed human case of swine flu appeared in close proximity to the largest pig factory in Mexico, which slaughters nearly a million pigs a year (out of a country-wide total of 15 million), may not have been a coincidence.

Warnings Unheeded

The public health community has been warning about the risks posed by factory farms for years. More than five years ago, in 2003, the American Public Health Association, the largest and oldest association of public health professionals in the world, called for a moratorium on factory farming.[28] In 2005, the United Nations urged that “[g]overnments, local authorities and international agencies need to take a greatly increased role in combating the role of factory-farming,” which, they said, combined with live animal markets, “provide ideal conditions for the [influenza] virus to spread and mutate into a more dangerous form.”[29]

Last April, the Pew Commission on Industrial Farm Animal Production released its final report. The prestigious, independent panel chaired by a former Kansas Governor and including a former U.S. Secretary of Agriculture, former Assistant Surgeon General, and the Dean of the University of Iowa College of Public Health, concluded that industrialized animal agriculture posed “unacceptable” public health risks: “Due to the large numbers of animals housed in close quarters in typical [industrial farm animal production] facilities there are many opportunities for animals to be infected by several strains of pathogens, leading to increased chance for a strain to emerge that can infect and spread in humans.”[30]

Specific to the veal crate-like metal stalls that confine breeding pigs like those on the North Carolina factory from which the first hybrid swine flu virus was discovered in North America, the Pew Commission asserted that “[p]ractices that restrict natural motion, such as sow gestation crates, induce high levels of stress in the animals and threaten their health, which in turn may threaten human health.”[31] Unfortunately we don’t tend to “shore up the levees” until after the disaster, but now that we know swine flu viruses can evolve to efficiently transmit human-to-human we need to follow the Pew Commission’s recommendations to abolish extreme confinement practices like gestation crates as they’re already doing in Europe, and to follow the advice of the American Public Health Association to declare a moratorium on factory farms.

A “Reservoir of Viruses” in the U.S.

With massive concentrations of farm animals within whom to mutate, these new swine flu viruses in North America seem to be on an evolutionary fast track, jumping and reassorting between species at an unprecedented rate.[32] This reassorting, Webster’s team concludes, makes the 65 million strong U.S. pig population an “increasingly important reservoir of viruses with human pandemic potential.”[33] “We used to think that the only important source of genetic change in swine influenza was in Southeast Asia,” said Christopher Olsen, a molecular virologist at the University of Wisconsin, Madison. Now, “we need to look in our own backyard for where the next pandemic may appear.”[34]

Dr. Michael Greger is director of public health and animal agriculture for The Humane Society of the United States.

——————————————————————————–

References

[1] Council on Foreign Relations. 2005. Session 1: Avian flu-where do we stand? Conference on the Global Threat of Pandemic Influenza, November 16. http://cfr.org/publication/9230/council_…uenza_session_1.html

[2] Belshe RB. 2005. The origins of pandemic influenza-lessons from the 1918 virus. New England Journal of Medicine 353(21):2209-11.

[3] Johnson NPAS, Mueller J. Updating the accounts: global mortality of the 1918–1920 “Spanish” influenza pandemic. Bull Hist Med. 2002;76:105–15.

[4] Zhou NN, Senne DA, Landgraf JS, et al. 1999. Genetic reassortment of avian, swine, and human influenza A viruses in American pigs. Journal of Virology 73:8851-6. http://birdflubook.org/resources/ZHOU8851.pdf

[5] Wuethrich B. 2003. Chasing the fickle swine flu. Science 299:1502-5. http://birdflubook.org/resources/WUETHRICH1502.pdf

[6] Zhou NN, Senne DA, Landgraf JS, et al. 1999. Genetic reassortment of avian, swine, and human influenza A viruses in American pigs. Journal of Virology 73:8851-6. http://birdflubook.org/resources/ZHOU8851.pdf

[7] Webby RJ, Swenson SL, Krauss SL, Gerrish PJ, Goyal SM, and Webster RG. 2000. Evolution of swine H3N2 influenza viruses in the United States. Journal of Virology 74:8243-51.

[8] Rabadan, R. 2009. Influenza A (H1N1) “swine flu”: worldwide (04) [1] ProMED Digest 2009. 28 April. Volume 2009 : Number 196. http://www.promedmail.org/pls/otn/f?p=2400:1001:1580522401053605::NO::F2400_P1001_BACK_PAGE,F2400_P1001_
PUB_MAIL_ID:1000,77250.

[9] Webby RJ, Swenson SL, Krauss SL, Gerrish PJ, Goyal SM, and Webster RG. 2000. Evolution of swine H3N2 influenza viruses in the United States. Journal of Virology 74:8243-51.

[10] Environmental Defense. 2000. Factory hog farming: the big picture. November. http://www.edf.org/documents/2563_FactoryHogFarmingBigPicture.pdf

[11] Duke University Center on Globalization, Governance and Competitiveness. 2006. Hog farming overview. February 23. http://www.soc.duke.edu/NC_GlobalEconomy/hog/overview.php

[12] North Carolina Department of Agriculture and Consumer Services. 2001. North Carolina agriculture overview. February 23. http://ncagr.com/stats/general/livestoc.htm

[13] Wuethrich B. 2003. Chasing the fickle swine flu. Science 299:1502-5. http://BirdFluBook.org/resources/WUETHRICH1502.pdf

[14] Brown IH. 2000. The epidemiology and evolution of influenza viruses in pigs. Veterinary Medicine 74:29-46. http://BirdFluBook.org/resources/Brown29.pdf

[15] 1993. Overcrowding pigs pays-if it’s managed properly. National Hog Farmer, November 15.

[16] Wuethrich B. 2003. Chasing the fickle swine flu. Science 299:1502-5. http://BirdFluBook.org/resources/WUETHRICH1502.pdf

[17] Webster RG and Hulse DJ. 2004. Microbial adaptation and change: avian influenza. Revue Scientifique et Technique 23(2):453-65.

[18] USDA. 2009. Poultry Slaughter 2008. Annual Summary. http://usda.mannlib.cornell.edu/usda/current/PoulSlauSu/PoulSlauSu-02-25-2009.pdf

[19] USDA. 2009. Chickens and Eggs 2008 Summary. http://usda.mannlib.cornell.edu/usda/current/ChickEgg/ChickEgg-02-26-2009.pdf

[20] Wuethrich B. 2003. Chasing the fickle swine flu. Science 299:1502-5. http://birdflubook.org/resources/WUETHRICH1502.pdf

[21] Shields DA and Mathews KH Jr. 2003. Interstate livestock movements. USDA Economic Research Service: Electronic Outlook Report from the Economic Research Service, June. usda.mannlib.cornell.edu/reports/erssor/livestock/ldp-mbb/2003/ldp-m108-01.pdf

[22] MacKenzie D. 1998. This little piggy fell ill. New Scientist, September 12.

[23] Ibid.

[24] Delgado C, Rosegrant M, Steinfeld H, Ehui S, and Courbois C. 1999. Livestock to 2020: the next food revolution. Food, Agriculture, and the Environment Discussion Paper 28. For the International Food Policy Research Institute, the Food and Agriculture Organization of the United Nations and the International Livestock Research Institute. http://ifpri.org/2020/dp/dp28.pdf

[25] Webster RG, Sharp GB, and Claas CJ. 1995. Interspecies transmission of influenza viruses. Americal Journal of Respiratory and Critical Care Medicine 152:525-30.

[26] MacKenzie D. 1998. This little piggy fell ill. New Scientist, September 12, p. 1818.

[27] Ibid.

[28] American Public Health Association. 2003. Precautionary moratorium on new concentrated animal feed operations. Policy number 20037. www.apha.org/advocacy/policy/policysearch/default.htm?id=1243

[29] United Nations. 2005. UN task forces battle misconceptions of avian flu, mount Indonesian campaign. UN News Centre, October 24. un.org/apps/news/story.asp?NewsID=16342&Cr=bird&Cr1=flu

[30] Pew Commission on Industrial Farm Animal Production. 2008. Expert panel highlights serious public health threats from industrial animal agriculture. Press release issued April 11. www.pewtrusts.org/news_room_detail.aspx?id=37968  Accessed August 26, 2008.

[31] Pew Commission on Industrial Farm Animal Production. 2008. Putting meat on the table: industrial farm animal production in America. Executive summary, p. 13. www.ncifap.org/_images/PCIFAPSmry.pdf  Accessed August 26, 2008.

[32] Wuethrich B. 2003. Chasing the fickle swine flu. Science 299:1502-5. http://birdflubook.org/resources/WUETHRICH1502.pdf

[33] Webby RJ, Rossow K, Erickson G, Sims Y, and Webster R. 2004. Multiple lineages of antigenically and genetically diverse influenza A virus co-circulate in the United States swine population. Virus Research 103:67-73. http://BirdFluBook.org/resources/webby67.pdf

[34] Wuethrich B. 2003. Chasing the fickle swine flu. Science 299:1502-5. http://BirdFluBook.org/resources/WUETHRICH1502.pdf

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2 Responses to “H1N1 flu virus link to USA pig industry”

  1. Dites AAAAA… (comme Agro-industrie) @ Sang et chlorophylle Says:

    […] Article de Michael Greger, directeur de la santé publique et de l’élevage pour “The Humane Society of the United States”. Le “Bulletin de l’Académie vétérinaire de France” écrivait également en 2004 : […]

  2. CDHPSA » Blog Archive » Le modèle agro-industriel mis en en cause ATTAC 6 Mai Says:

    […] de la santé publique et de l’élevage pour “The Humane Society of the United States”,https://sheepdrove.wordpress.com/200…. Le “Bulletin de l’Académie vétérinaire de France” écrivait également en 2004 : […]

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