{"id":16805,"date":"2021-01-22T09:00:36","date_gmt":"2021-01-22T14:00:36","guid":{"rendered":"https:\/\/www.vrg.org\/blog\/?p=16805"},"modified":"2021-01-18T14:50:26","modified_gmt":"2021-01-18T19:50:26","slug":"risk-of-viral-pandemics-from-concentrated-animal-feeding-operations-and-wet-markets","status":"publish","type":"post","link":"https:\/\/www.vrg.org\/blog\/2021\/01\/22\/risk-of-viral-pandemics-from-concentrated-animal-feeding-operations-and-wet-markets\/","title":{"rendered":"Risk of Viral Pandemics from Concentrated Animal Feeding Operations and Wet Markets"},"content":{"rendered":"\n
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Researched by Jacqueline Tang, VRG Intern<\/p>\n\n\n\n

The Covid-19 pandemic, caused by the novel coronavirus known as SARS-CoV-2,\npresents many unique challenges to public health. People may be wondering how a\nmassive pandemic allegedly arose from one wet market\u2014and how to prevent the\nnext crisis. Unfortunately, the answer is complicated. It involves our\nrelationships with animals (both wild and domestic) and with the environment.\nClimate change further influences all of these interactions.<\/p>\n\n\n\n

   Recently wet markets (that sell\nlive animals for food) have come under scrutiny for the dangerous mixing of\nwild animals and humans. The criticism of these markets is filled with\nethnocentrism and Western ideals. Although wet markets are undoubtedly perfect\nplaces for viral multiplication and transmission, people fail to recognize two\nother major factors:<\/p>\n\n\n\n

1. The role of concentrated animal feeding operations (CAFOs) in spreading\ninfectious disease to people.<\/p>\n\n\n\n

2. Humans\u2019 relationships with the Earth\u2019s ecosystems, both near and\ndistant. <\/p>\n\n\n\n

THE ORIGINS OF ZOONOTIC DISEASES<\/p>\n\n\n\n

Viruses that come from animals, also called zoonotic viruses, are a major\nthreat to society and public health. According to the Centers for Disease\nControl and Prevention, (CDC), a division of the United States Department of\nHealth and Human Services, \u201c… scientists estimate that more than six out of\nevery 10 known infectious diseases in people can be spread from animals, and\nthree out of every four new or emerging infectious diseases in people come from\nanimals.\u201d1<\/sup> Since humans come in contact with animals in many ways,\nit\u2019s important to consider different situations where zoonotic diseases can be\neasily transmitted across species.          <\/p>\n\n\n\n

WET MARKETS<\/p>\n\n\n\n

Recently, wet markets have come under scrutiny for the dangerous\ncommingling of wild animals and humans. Also, they bring an exotic combination\nof animals, which normally are not found close to each other in the wild,\ntogether in one place. At a wet market:<\/p>\n\n\n\n

A. Wild animals can infect domesticated animals.<\/p>\n\n\n\n

B. Viruses can spread between different species. <\/p>\n\n\n\n

     Birds and bats especially carry\nmany viruses. When they come in contact with an animal of a different species,\na virus can mutate and adapt, eventually gaining the ability to infect a new\nhost. In this manner, viruses spread widely.2<\/sup><\/p>\n\n\n\n

     Some viruses are unable to\ndirectly infect a human, including avian (from birds) forms of influenza and\nsome types of coronaviruses. These viruses require an intermediate host that\nserves as the go-between such that the virus can enter a new species. In the\nintermediate host, a virus changes sufficiently through mutations that enable\nit to adapt to a new host. Later, when given the chance to infect a human at\nclose proximity, it may be able to do so by binding to specific cell receptors.3,4<\/sup><\/p>\n\n\n\n

     The risk of wet markets stems\nfrom being places that allow for many different types of species to come in\ncontact for the first time. This gives viruses numerous potential hosts and\ngreater possibility of genetic recombination through mutation. Without certain\nmutations, a particular virus may not be able to exploit a new species. <\/p>\n\n\n\n

     The cramped conditions in wet markets lead to animals being under severe stress. As a result, wild animals, already carrying many viruses that they are immune to, will shed more viral particles in the market.5<\/sup> This means that there is a greater chance of viral infection for humans and other animals that are in the wet market. Unfortunately, stressful conditions for animals is not unique to wet markets. Conventional animal agriculture also places extreme stress on food animals.<\/p>\n\n\n\n

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CONCENTRATED ANIMAL FEEDING OPERATIONS (CAFOs)<\/p>\n\n\n\n

According to the Natural Resources Conservation Service, a division of the\nUnited States Department of Agriculture (USDA), CAFOs \u201ccongregate animals,\nfeed, manure and urine, dead animals, and production operations on a small land\narea.\u201d6<\/sup><\/p>\n\n\n\n

     CAFOs present many challenges for public\nhealth. The risk lies in their scale and sanitation. Many individuals of the\nsame species, known as monocultures, are housed together in small cages, rooms,\nor buildings. If a virus is able to infiltrate (either from wild animal, human,\nor another method), it will easily spread between animals. <\/p>\n\n\n\n

     The lack of genetic diversity within\nlivestock also facilitates viral transmission between animals.7<\/sup> The\nFood and Agriculture Organization of the United Nations (FAO of the UN) stated\nthat \u201clivestock health is the weakest link in our global health chain, and\ndisease drivers in livestock as well as wildlife are having increasing impacts\non humans.\u201d8<\/sup><\/p>\n\n\n\n

THE WET MARKET-CAFO CONNECTION<\/p>\n\n\n\n

Besides the contributions to pandemic risk that wet markets and CAFOs\npresent when considered individually, their connection is also problematic. For\nexample, consider the case of influenza, a common virus in poultry and swine. Influenza\nis more common within CAFOs compared to wet markets. For example, in a\nsystematic review over a six-year period, researchers noted that of 364 avian\ninfluenza outbreaks, 56.1% originated in poultry CAFOs while only 0.8% started\nin wet markets.9<\/sup><\/p>\n\n\n\n

     Scientists also report that many viruses\nundergo genetic recombination that occur among individuals of the same species and<\/em>\nbetween species. In other words, if a wild animal comes in contact with\nlivestock, either directly or indirectly, it can easily spread certain viruses\nto the domestic food animals.10<\/sup><\/p>\n\n\n\n

     Typically, viruses are not very pathogenic in\nthe wild host. Once infected by a wild virus, domestic animals serve as\n\u201camplifier hosts\u201d in which that virus often becomes more pathogenic than it was\nin the native species. Through genetic recombination and\/or mutation, the wild\nvirus becomes adapted to the new host.11<\/sup> <\/p>\n\n\n\n

     The transport of both domesticated and wild\nanimals can also magnify zoonotic viruses. The animals being transported might\nbe exposed to viruses that their immune systems have never encountered. During\nthis exposure, foreign viruses have the potential to recombine and create completely\nnovel viruses.12<\/sup>      <\/p>\n\n\n\n

     J.F. Chan and colleagues,<\/em>\nin a 2013 Trends in Microbiology<\/em> article state that in the wild, bats\nand birds are favorable reservoirs for most emerging viruses because of several\n\u201cunique ecological, biological, immunological, and genetic features.\u201d The loss\nof biodiversity and habitats for bats and birds leads to an increased\ninteraction with humans and other species, including domesticated animals. The\nresearchers report that the increased crowding of different wildlife species at\nwet markets has made it easier for viruses to jump between species.13<\/sup>\n<\/p>\n\n\n\n

     In some countries, animal\nagriculture also occurs in mixed species settings. For example, in China,\nit\u2019s common to raise pigs along with ducks and other avian species. 14<\/sup>\nThe high probability of viral transmission caused by interspecies mixing cannot\nbe overstated. <\/p>\n\n\n\n

THE ROLE OF INTERMEDIATE HOSTS IN VIRAL TRANSMISSION<\/p>\n\n\n\n

In a 2020 editorial by A. Rodriguez-Morales and fellow researchers\npublished in Le Infezioni in Medicina <\/em>many viruses use intermediate\nhosts like civets or camels because they cannot spread directly from the\noriginal infected animal (bat or bird) directly to humans.15<\/sup> <\/p>\n\n\n\n

     M. Konda and fellow\ninvestigators,<\/em> in a 2020 review article in Cureus<\/em> summarize the\nviral process in intermediate hosts16<\/sup>: <\/p>\n\n\n\n

1. Mutates and recombines in intermediate hosts, thus adapting to humans <\/p>\n\n\n\n

2. Binds to the correct cell receptor in humans<\/p>\n\n\n\n

3. Enters the human cell <\/p>\n\n\n\n

4. Integrates its own genetic material into the human cell\u2019s<\/p>\n\n\n\n

5. Commands the human cell to reproduce virus.        <\/p>\n\n\n\n

6. Human cell continues to reproduce more virus. <\/p>\n\n\n\n

     Scientists hypothesize that\nSARS-CoV-2, the virus that causes Covid-19, used an intermediate host between\nbat and humans just like its viral cousins responsible for other recent\ncoronavirus outbreaks.17<\/sup> <\/p>\n\n\n\n

CONCLUSIONS: PANDEMICS, WET MARKETS, AND CAFOs<\/p>\n\n\n\n

Both wet markets and CAFOs present unique challenges for the future of\npublic health. CAFOs, with thousands of genetically similar animals in close\nproximity, provide the perfect environment for a virus to spread. <\/p>\n\n\n\n

     Wet markets bring hundreds of\nwild species together in one place. They allow for interspecies viral\ntransmission and the potential of recombination to form novel pathogens. Wet\nmarkets also allow virus-infected animals, like wild bats and birds, to come\ninto contact with humans and domestic animals. <\/p>\n\n\n\n

     Both CAFOs and wet markets may have\nvery poor sanitation and living conditions for animals, creating stressed\nanimals that shed more virus. This situation facilitates rapid viral spread. <\/p>\n\n\n\n

     Wet markets and CAFOs jeopardize\npublic health and food security. Research should focus on prevention of\npandemics in both types of food systems. Ultimately, humans need to reevaluate\ntheir role in the Earth\u2019s ecosystems if we hope to prevent the next global\npandemic of a zoonotic virus like SARS-CoV-2.   \n<\/p>\n\n\n\n

Notes from the editors:<\/em><\/p>\n\n\n\n

WHAT IS A WET MARKET?<\/p>\n\n\n\n

According to researchers, \u201cA\ntypical wet market is a partially open commercial complex with vending stalls\norganized in rows; they often have slippery floors and narrow aisles along\nwhich independent vendors primarily sell \u2018wet\u2019 items such as meat, poultry,\nseafood, vegetables, and fruits.\u201d See: https:\/\/link.springer.com\/article\/10.1007\/s10460-019-09987-2<\/a>\n<\/p>\n\n\n\n

     In this sense of the term, wet markets\nexist all over the world, including the United States, where they are called \u201cfarmer’s\nmarkets.\u201d<\/p>\n\n\n\n

     In this paper, \u201cwet market\u201d refers to open\nmarkets selling live animals, including wild, domestic, and\/or domesticated\nwild animals, as well as animal products (eggs, meat, bones, organs, etc.).<\/p>\n\n\n\n

WHAT IS A CAFO (concentrated animal feeding operation)?<\/p>\n\n\n\n

The\nU.S. Environmental Protection Agency (EPA) defines Animal Feeding Operations (AFOs)\nas \u201cagricultural enterprises where animals are kept and raised in confined\nsituations. AFOs congregate animals, feed, manure and urine, dead animals, and\nproduction operations on a small land area. Feed is brought to the animals\nrather than the animals grazing or otherwise seeking feed in pastures, fields,\nor on rangeland. There are approximately 450,000 AFOs in the United States.\u201d\n19<\/sup><\/p>\n\n\n\n

     \u201cA CAFO is another EPA term for a large\nconcentrated AFO. A CAFO is an AFO with more than 1,000 animal units (an\nanimal unit is defined as an animal equivalent of 1,000 pounds live weight and\nequates to 1,000 head of beef cattle, 700 dairy cows, 2,500 swine weighing more\nthan 55 lbs, 125 thousand broiler chickens, or 82 thousand laying hens or\npullets) confined on site for more than 45 days during the year. Any size\nAFO that discharges manure or wastewater into a natural or man-made ditch,\nstream or other waterway is defined as a CAFO, regardless of size.\u201d19<\/sup><\/p>\n\n\n\n

References<\/p>\n\n\n\n

1. Zoonotic Diseases. cdc.gov. https:\/\/www.cdc.gov\/onehealth\/basics\/zoonotic-diseases.html.\nPublished July 14, 2017. Accessed November 4, 2020. <\/p>\n\n\n\n

2. Chan JF, To KK, Tse H,\nJin DY, Yuen KY. Interspecies transmission and emergence\nof novel viruses: lessons from bats and birds. Trends Microbiol<\/em>.\n2013;21:544-555. <\/p>\n\n\n\n

3. Johnson KEE, Song T,\nGreenbaum B, Ghedin E. Getting the flu: 5 key facts about influenza virus\nevolution. PLoS Pathog<\/em>. 2017;13:e1006450. Published 2017 Aug 24. <\/p>\n\n\n\n

4. Konda M, Dodda B, Konala\nVM, Naramala S, Adapa S. Potential Zoonotic Origins of SARS-CoV-2 and Insights\nfor Preventing Future Pandemics Through One Health Approach. Cureus<\/em>.\n2020;12:e8932. Published 2020 Jun 30.<\/p>\n\n\n\n

5. Brook CE, Boots M,\nChandran K, et al. Accelerated viral dynamics in bat cell lines, with implications\nfor zoonotic emergence. Elife<\/em>. 2020;9:e48401. Published 2020 Feb 3.<\/p>\n\n\n\n

6. Animal Feeding\nOperations. NRCS.\nhttps:\/\/www.nrcs.usda.gov\/wps\/portal\/nrcs\/main\/national\/plantsanimals\/livestock\/afo\/.\nAccessed November 4, 2020. <\/p>\n\n\n\n

7. Jones BA, Grace D, Kock\nR, et al. Zoonosis emergence linked to agricultural intensification and\nenvironmental change. Proc Natl Acad Sci U S A<\/em>. 2013;110:8399-8404.\ndoi:10.1073\/pnas.1208059110<\/p>\n\n\n\n

8. Food and Agriculture Organization of the\nUnited Nations. World Livestock 2013 \u2013 Changing Disease Landscapes<\/em>. Rome, IT: FAO; 2013.<\/p>\n\n\n\n

9. Chatziprodromidou IP,\nArvanitidou M, Guitian J, et al. Global avian influenza outbreaks 2010-2016: a\nsystematic review of their distribution, avian species and virus subtype.\nSystematic Reviews. 2018 Jan;7(1):17.<\/p>\n\n\n\n

10. Keesing F, Belden LK,\nDaszak P, et al. Impacts of biodiversity on the emergence and transmission of\ninfectious diseases. Nature<\/em>. 2010;468:647-652.<\/p>\n\n\n\n

11. Jones BA, Grace D, Kock\nR, et al. Zoonosis emergence linked to agricultural intensification and\nenvironmental change. Proc Natl Acad Sci U S A<\/em>. 2013;110:8399-8404.\n<\/p>\n\n\n\n

12. Liverani M, Waage J,\nBarnett T, et al. Understanding and managing zoonotic risk in the new livestock\nindustries. Environ Health Perspect<\/em>. 2013;121:873-877. <\/p>\n\n\n\n

13. Chan JF, To KK, Tse H,\nJin DY, Yuen KY. Interspecies transmission and emergence\nof novel viruses: lessons from bats and birds. Trends Microbiol<\/em>.\n2013;21:544-555. <\/p>\n\n\n\n

14. Keck F. Livestock Revolution and Ghostly\nApparitions: South China as a Sentinel\n Territory for Influenza\nPandemics. Current Anthropology<\/em>.\n2019:60:S20.<\/p>\n\n\n\n

15. Rodriguez-Morales AJ,\nBonilla-Aldana DK, Balbin-Ramon GJ, et al. History is repeating itself:\nProbable zoonotic spillover as the cause of the 2019 novel Coronavirus\nEpidemic. Infez Med<\/em>. 2020;28:3-5.<\/p>\n\n\n\n

16. Konda M, Dodda B, Konala VM, Naramala S, Adapa S. Potential Zoonotic Origins of SARS-CoV-2 and Insights for Preventing Future Pandemics Through One Health Approach.\u00a0Cureus<\/em>. 2020;12:e8932. Published 2020 Jun 30.<\/p>\n\n\n\n

17. Hu T, Liu Y, Zhao M,\nZhuang Q, Xu L, He Q. A comparison of COVID-19, SARS and MERS. PeerJ<\/em>.\n2020;8:e9725. Published 2020 Aug 19.<\/p>\n\n\n\n

18. Wet Market. Merriam-Webster.\nhttps:\/\/www.merriam-webster.com\/dictionary\/wet market. Accessed November 5,\n2020. <\/p>\n\n\n\n

19. Animal Feeding\nOperations. NRCS.\nhttps:\/\/www.nrcs.usda.gov\/wps\/portal\/nrcs\/main\/national\/plantsanimals\/livestock\/afo\/.\nAccessed <\/p>\n\n\n\n

Jacqueline Tang did a Vegetarian\nResource Group internship while a pre-med and public health major at Johns\nHopkins University. <\/em><\/p>\n\n\n\n

The contents of this posting,\nour website, and our other publications, including Vegetarian Journal, are not\nintended to provide personal medical advice. Medical advice should be obtained\nfrom a qualified health professional. We often depend on product and ingredient\ninformation from company statements. It is impossible to be 100% sure about a\nstatement, info can change, people have different views, and mistakes can be\nmade. Please use your best judgment about whether a product is suitable for\nyou. To be sure, do further research or confirmation on your own.<\/p>\n","protected":false},"excerpt":{"rendered":"

Researched by Jacqueline Tang, VRG Intern The Covid-19 pandemic, caused by the novel coronavirus known as SARS-CoV-2, presents many unique challenges to public health. People may be wondering how a massive pandemic allegedly arose from one wet market\u2014and how to prevent the next crisis. Unfortunately, the answer is complicated. It involves our relationships with animals […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-16805","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/www.vrg.org\/blog\/wp-json\/wp\/v2\/posts\/16805","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.vrg.org\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.vrg.org\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.vrg.org\/blog\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.vrg.org\/blog\/wp-json\/wp\/v2\/comments?post=16805"}],"version-history":[{"count":2,"href":"https:\/\/www.vrg.org\/blog\/wp-json\/wp\/v2\/posts\/16805\/revisions"}],"predecessor-version":[{"id":16810,"href":"https:\/\/www.vrg.org\/blog\/wp-json\/wp\/v2\/posts\/16805\/revisions\/16810"}],"wp:attachment":[{"href":"https:\/\/www.vrg.org\/blog\/wp-json\/wp\/v2\/media?parent=16805"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.vrg.org\/blog\/wp-json\/wp\/v2\/categories?post=16805"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.vrg.org\/blog\/wp-json\/wp\/v2\/tags?post=16805"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}