At a time when the world is reeling under the impact of the deadly CoVID-19 (Coronavirus Disease 2019) outbreak, I find myself, probably like many others, trying to come to terms with my new sedentary lifestyle. Besides other things, I spend at least a couple of hours each day on news networks, tracking latest developments on the outbreak, and listening to various world leaders and health-care experts speak, something I find interesting. For instance, ever since the virus has struct the United States of America, President Donald Trump has time and again referred to it as the “Chinese Virus” or the “Wuhan Virus”. Claiming to have done their research, several news channels are also convinced that the virus, like many other material goods in today’s world, is made in China. Although controversial and debatable, these claims cannot be completely debunked. In this blog article, I explore the origins and transmission lines of some of the other recent viruses that proved to be fatal to humankind, while also trying to understand the role of viruses at the human-animal interface.
CoVID-19 or 2019-nCoV (novel Coronavirus) is an infectious disease that was first reported in December 2019 in Wuhan, the capital of Hubei, China (Salata et al., 2019), and has since spread to almost all parts of the globe, causing the World Health Organization to declare it as a pandemic. The origin of the outbreak has been linked to Wuhan’s Huanan Seafood Wholesale Market (Salata et al., 2019), and although there is still no concrete evidence, scientists believe that the virus causing CoVID-19 jumped from bats to humans through a transmitter animal, most likely being the pangolin (van Staden, 2020). However, this is not the first time that a Coronavirus (CoV) has led to a health crisis. SARS-CoV (Severe Acute Respiratory Syndrome Coronavirus) was responsible for the SARS epidemic of 2002-03 that affected > 30 countries in five continents, resulting in 8,098 human cases and 774 fatalities (Greatorex et al., 2016). SARS-CoV was traced to wildlife wet markets in China where the virus spread from bats, the reservoir host, to palm civets, the amplification host while the two species were kept in market stalls in close proximity to each other (Fong, 2017; Rostal et al., 2013). The virus then jumped from palm civets to humans during contact and handling procedures at the market while being readied for consumption as food (Fong, 2017).
Wildlife markets in China’s Guangzhou, where SARS-CoV is said to have originated from, are known to trade in a variety of species such as palm civets, ferret badgers, barking deer, wild boars, hedgehogs, foxes, squirrels, bamboo rats, gerbils, various species of snakes, and endangered leopard cats, along with domestic dogs, cats, and rabbits (Karesh et al., 2005). In these markets, wild animals, including birds, mammals and reptiles, along with domestic animals are all kept in close proximity to one another and in very unhygienic conditions (Rostal et al., 2013). Markets such as these are then particularly prone to cross-species pathogen transmission due to the combination of high wildlife volumes, high-risk taxa for wildlife diseases and poor biosafety (Greatorex et al., 2016).
A similar cross-species transmission of Coronavirus occurred in 2012 in Jeddah, Saudi Arabia, when MERS-CoV (Middle East Respiratory Syndrome Coronavirus) possibly jumped from bats, the reservoir host, to camels, the intermediate host and then to humans leading to the MERS outbreak which resulted in 834 cases and 288 deaths (Fong, 2017). In this case, animal to human transmission may have occurred when infected camels came in contact with humans at slaughterhouses (Farag et al., 2015). Another virus which has jumped from animals to humans is the Simian Immunodeficiency Virus (SIV). It is believed that SIV jumped several times to people hunting and consuming non-human primates and eventually mutated into the Human Immunodeficiency Virus (HIV) strains, resulting in the Acquired Immunodeficiency Syndrome (AIDS) (Rostal et al., 2013) which has affected millions across the globe.
Viruses that originate in animals are known as zoonotic viruses and have a high tendency for recombination and mutation, allowing them to adapt to new hosts and novel ecological niches (Lau et al., 2005), and thereby making them extremely potent. According to one estimate, about 75% of emerging infectious diseases that pose a threat to global public health have zoonotic origins (Daszak et al., 2007). These viruses are able to proliferate, or in medical terms, “spillover”, by overcoming not just species barriers but also geographical barriers, thanks to the large-scale movement of wild animals through both legal and illegal global trade. Each year billions of plants, animals and their derivatives are moved around the world as trophies, food, clothing, decorative items, pets, and traditional medicine (Rosen & Smith, 2010).
Further, with economic development and the opening of borders, for instance, between China and its neighbouring countries in South-east Asia, the number of species entering the trade, including ‘rarities’ from remote locations have substantially risen (Zhang, et al., 2008). The increasingly global scope of the trade, combined with the ease and speed of modern-day transport, has ensured that not just animals, but also the viruses that they host are able to safely move around the globe (Karesh et al., 2005). As a matter of fact, air transport has been directly and indirectly responsible in the past for the inter and intra-continental spread of zoonotic diseases such as SARS, dengue fever and novel H1N1 (Mao et al., 2015), and at present has aided CoVID-19 in becoming a pandemic.
While throughout much of this article I have highlighted the origin and transfer mechanisms of zoonotic viruses, what receives much less attention are the viruses (e.g. measles, herpesviruses, poliovirus, etc.) which originate in humans and infect animals, and which are collectively referred to as “anthropozoonotic” viruses (Rostal et al., 2013). However, regardless of the categories that they are placed in, viruses, by mutating and changing their characteristics, have time and again proved their capability of moving back and forth between human and non-human species (Karesh & Cook, 2005). Just as societies, governments and economies are open to and accepting of an increasingly globalized world (Sheppard & Lynn, 2004), the arrival and spread of novel viruses are a reminder of the ongoing openness of both human and animal bodies to other forms of biological life (Greenhough, 2012). Outbreaks like CoVID-19 are also a grim reminder that animals are not always victims, and by acting as hosts and transmitters of deadly viruses, they do possess the ability to make humans prey (Ginn et al., 2014).
In conclusion, I would like to return to the title of my blog article Where Humans and Virus Meet. While geographically distinct wilderness spaces may permit only a limited number of wild species to meet and interact, wildlife markets are unique spaces where humans and non-humans, both domestic as well as wild species from distinct geographies, meet, mingle and transact. The wildlife market space is symbolic of not just how human agency affects non-human others through the processes of harvesting and consumption, but also of how human agency itself is affected by non-human others through the processes of pathogen transmission (Greenhough, 2012). According to Joost Van Loon (2005), an epidemic space “is a dense space, marked by complex connections between a wide range of nodes: patients, medical staff, equipment, modes of transportation, roads, hospital wards, virulent pathogens, parasites, animals, communication technologies, military personnel, weapons, barbed wire…”. My question is, “will epidemic spaces exist if wildlife market spaces cease to exist?”
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Featured Image by Miroslava Chrienova from Pixabay
2 responses to “Where Humans and Virus Meet”
[…] Where Humans and Virus Meet […]
I must say, this was a comprehensive and very easy to follow- blog. Lucid yet effective! Thank you!