Putting aside that there are people who believe COVID is a form of Chinese bio-terrorism (!), a widely held view is that the SARS COVID19 virus had its beginnings in the wet markets of Wuhan. These are lightly regulated farmers markets that sell everything including exotic animals like bats and pangolin (a kind of aardvark). The strangeness of the Chinese diets or the lack of regulation or misunderstanding or prejudice or mistrust of the Chinese government has led people to believe that closing of Chinese wet markets would reduce the risk of future outbreaks.
This is poorly reasoned. A much bigger threat comes from Concentrated Animal Feeding Operations (CAFO).
It is true that 70% of novel human diseases that have emerged in humans over recent decades are of animal origin. But the source is not exotic species but usually traditional livestock concentrated in large populations. The historical evidence tells us this and science explains why.
- 2015 saw the introduction of H5N1 – avian influenza – into the US. While its spread devastated chicken and turkey farms, it was not easily contracted by humans. This was fortunate because it had a mortality rate of 50% for people who became infected. For this reason, in the early days of the spread it caused quite a panic.
- The H1N1 ‘swine flu’ came, as the name suggests, from pigs and is believed to have had factory farms as a source. The swine flu killed 12,000 Americans and hospitalized almost 300,000.
- The 1918 Spanish Flu is believed to have killed more than 50 million people worldwide. While there is a lot of ambiguity surrounding the beginnings of the 1918 pandemic (and a possible Chinese connection) the source appears was likely pigs, but maybe chickens and maybe both.
Micro-organisms are constantly passed between animals and humans; some are benign, some like salmonella frequently make people sick. There are several variants of salmonella now endemic (constantly present) in bird populations but salmonella is rarely passed between people. There are other forms of bacteria that can cause diseases like cholera and leprosy that are passed from person to person but are not present in animal populations. Most of the communicable diseases caused by bacteria have been identified and are understood by science and treatments have been developed.
Bacteria are tiny, single cell organisms. Bacteria evolve much like other organisms, so that there are billions of different kinds. But much smaller and much less complex are viruses. Viruses aren’t technically alive, they are strands of RNA protein that can replicate themselves inside other cells. Viruses don’t evolve through reproduction; they don’t eat, don’t have cell structure. What they do have is a process called re-assortment, which is a process of exchanging genetic material with other similar viruses. This is much faster and easier than evolution through reproduction.
Viruses like influenza are constantly changing – mutating – through introduction to genetic material. This, combined with changes when genes are copied over and over again (antigenic drift), means new variants of virus are always being created. Almost of these re-assortments ae failures in that they do not easily spread easily between more complex organisms. Some are benign in that they don’t affect the host organisms in meaningful ways. But occasionally there is a mutation that produces a new variant of a virus that is easily spread between organisms. These are called successful. And sometimes they can be deadly to people.
If you think about it, it is really a numbers game. The more the organisms involved, the more opportunity for re-assortment. A peasant farmer with one pig and one cow will offer viruses little interaction with genetic material. Also, if a deadly virus develops in an solitary animal and it dies, that virus dies too without being passed along. A CAFO with hundreds of animals, very much in close quarters, offers a rich environment for both virus mutation and transmission. Additionally, the fact that the animals are so close in their genetics means that the process of mutation is actually accelerated. From a United Nations report on the livestock and disease: “Epidemiology states that the transmission of a pathogen tends to increase with host density (Kilpatrick and Altizer, 2012). In this process, a pathogen may turn into a hyper-virulent disease agent; in monocultures involving mass rearing of genetically identical animals that are selected for high feed conversion, an emerging hyper-virulent pathogen will rapidly spread within a flock or herd“
More than 90% of the meat consumed in this country comes from CAFOs. Not only do viruses mutate and spread quickly in these populations, the scale of these operations exacerbates the problem of antibiotic resistance. The transportation of pigs domestically and internationally has led to some serious concern over the next swine-based influenza. We shouldn’t worry about the consumption of bats half a world away. We should instead be concerned about the giant virus laboratories we have created with CAFOs.