Saturday, 1 February 2020

Letter to the Editor: Zoonoses and Disease Outbreaks - It's Time We Take A Closer Look At Animal Agriculture, Not Just The Wildlife Trade


The international community heaved a collective sigh of relief when China announced a ban, albeit temporary, on wildlife trade in an effort to contain the 2019-nCoV coronavirus (Jan 26). Environmental and wildlife conservation groups both outside and within China wasted no time in urging China to make the ban permanent, citing the protection of human health, biodiversity, and wildlife populations as the reason. 

It would be commendable if China were to codify and enforce a permanent ban on wildlife consumption and trade, but in the meantime, a temporary ban would help contain further spread of the virus and give some measure of protection for wildlife. Yet the recent plaudits for China’s bold move is marred by the fact that until the announcement was made, the outrage and vitriol directed at China by the media and international community smacks of double standards, hypocrisy, racial malice, and schadenfreude. 

The media and international community persuaded itself that China’s predilection for consuming wildlife and exotic meats is the reason why it does not deserve its recent wealth and rise as a world superpower, and that its citizens deserve to suffer for their barbarism and dirty and uncivilised ways. If the international community were really so concerned about wildlife conservation and biodiversity, we would see the same level of outrage over fox hunting in the United Kingdom, the USA’s trophy hunting industry, the systematic hunting of minke whales by Norway, Australia’s kangaroo meat industry, and Canada’s annual slaughter of seals and sea lions. Yet for the most part, these countries have been able to carry on exploiting and killing wildlife with relative impunity, and these activities are passed off as being civilised, sophisticated, or an economic or environmental necessity. 

The fact that some countries with a longstanding culture of exploiting, killing, and consuming wildlife have managed to avoid being the country of origin of zoonotic disease outbreaks, while other countries suffer huge losses from the same, indicates that there is more we have yet to learn about the wildlife trade, the spread of pathogens, and ways to contain and control disease outbreaks. 

It would be neat and convenient indeed if the blame for the 2019-nCoV coronavirus outbreak could be placed squarely on Wuhan’s wildlife markets. However, scientists are still struggling to pinpoint the original host of the virus and how it first infected people. The premature blaming of snakes and bats as the original hosts of the virus shows us how truly novel this coronavirus is and how little we know about it, and indeed, about other zoonotic diseases. Until today, the scientific and medical community have yet to be able to confirm that Ebola originated from bats. 

This leaves us with two issues to be addressed, namely, that: 
(1) Wildlife needs to be protected in and of itself, and measures must be taken by all countries to end wildlife trade, ban the exploitation and killing of wildlife, and halt the destruction of wildlife habitats, whether or not the killing of any particular species or population has an adverse impact on human health and safety; and 

(2) In order to protect human health, we need to protect animal health and welfare. To do so, we need to stop scapegoating citizens of developing nations who consume wildlife and bushmeat, and instead, examine how intensive animal agriculture and low animal welfare standards have directly resulted in threats to human health, safety, and well-being. 

Following China’s official announcement linking the virus to Wuhan’s wildlife markets, social media was rife with comments such as “Why can’t they just be civilised and eat domestic farmed animals like the rest of us?”, “Serves them right for eating endangered animals instead of animals raised for food!”, and even “Eat more chicken and beef!”, as if eating farmed meat could miraculously inoculate humans against zoonotic diseases. 

History has shown us repeatedly that not only does eating farmed meat not inoculate humans against diseases, but that intensive animal agriculture is a major driver of zoonosis and disease outbreaks. 

If zoonotic diseases such as SARS, Ebola, West Nile Virus, Nipah Virus, Avian Influenza, and 2019-nCoV were merely transmitted to those who directly handle and consume wildlife, they would not have had the pandemic effects that they did. But wildlife diseases can and do afflict domestic animals, and cross species to humans with alarming rapidity. Farm animals frequently become intermediate or amplifier hosts for pathogens. 

Researchers, including those from the Centre for Global Health Science and Security of Georgetown University, Washington DC, estimate that 70% of zoonotic diseases come from wildlife, and then made the leap from wildlife to humans. Deforestation and human encroachment into previously forested areas for agriculture have been identified as factors in the spread of zoonosis, as farm and domestic animals come into contact with wildlife and wild birds. The crowded and unhealthy conditions in factory farms then expedite the spread of viruses such as Avian Influenza, and bacterial pathogens, such as E. coli, Campylobacter and salmonella. The Japanese Encephalitis Virus, for instance, was transmitted by the Culex mosquito (which usually feeds on wild birds and mammals) to farmed pigs, which became carriers for the virus and then amplified these infections in humans. The Nipah Virus became an outbreak because virus-infected fruit bats transmitted their virus to the farmed pigs via the consumption of fruit contaminated with bat saliva or urine. In the case of the Nipah Virus outbreak in Malaysia, there was no evidence of direct transmission from bats to humans, and almost all the human cases had direct contact with the infected pigs. Clearly abstinence from hunting, poaching, and wildlife products would have made no difference at all in the case of the Nipah Virus. 

Intensive animal farming is usually characterised by high animal population density and low genetic diversity, both of which are factors that promote increased pathogen transmission and adaptation. Farmed poultry live in conditions that suppress their immunity and make them more susceptible to infections. Avian influenza virus is reported to be “subclinical or of low pathogenicity in wild birds”, yet become highly pathogenic when transmitted to domestic poultry. A 2010 study published in Veterinary Record reports that a large-scale UK survey found that battery-cage poultry farms are 6 times more likely than cage-free farms to be infected with the strain of salmonella most commonly associated with food poisoning. 

The risk of zoonotic diseases must be managed through improvement in farm animal welfare standards, and disease management and control measures. These can include mitigating measures such as using slower-growing animal breeds, creating diets and management conditions that minimise stress to animals, increasing surveillance and vaccination to monitor and minimise the spread of disease, limiting live animal transportation time to reduce stress and cruelty, investing more in research and knowledge transfer to improve farm animal health and welfare standards, reducing non-therapeutic antibiotic use to reduce the risk of antibiotic resistance, and encouraging consumers to eat less or no meat products or replace conventional meat products with higher welfare animal products such as grass-fed beef or free-range or certified humanely raised poultry. 

On a personal level, we can reduce and mitigate the risk of zoonotic diseases and infections by choosing a plant-based diet and limiting our exposure to wildlife, which should remain wild and protected against unnecessary human contact. At an institutional level, those with the political and economic leverage must reduce and mitigate the said risk by disallowing deforestation and expansion of agricultural activities into forested areas in order to minimise wildlife-to-domestic-animal and animal-to-human viral spillover, tightening biosecurity controls in farms and places that process or handle animal products, improving animal health and welfare standards, replacing factory farming systems with more humane and sustainable systems, setting restrictions and guidelines on the transportation of livestock and poultry, and removing barriers and creating incentives for the development, production, and consumption of plant-based foods and lab-grown meat to replace and eventually phase out conventionally-produced farmed meat. 


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