Viral Origins: Past and Present Part 2

This is the second of 2 posts on the origin of SARS-CoV-2, and why we should all not simply regard it as a deeply traumatic, but once-in-a-lifetime experience. See also Viral Origins: Past and Present Part 1.

Why are Zoonoses increasing?

Zoonoses (human infections of animal origin) have become increasingly important in recent decades. Viral infections in this category include HIV, Ebola, West Nile Virus, and the Coronavirus diseases MERS, SARS, and most recently COVID-19 caused by SARS-CoV-2. This is not an accident: it results from the relentless tendency of humans to plunder ecosystems without regard for the consequences.

The COVID-19 Pandemic.

Industrial-scale farming in China has resulted in the economic marginalisation of millions of small farmers. These farmers have been forced to move into the production of more exotic species——animals that were once eaten only for subsistence. The bigger operations have, however, also pushed the farmers out physically, as they have taken up more prime farming land. The small farmers have been forced to operate closer to zones which can’t be cultivated, such as forests where bats are found. This is a problem because bats are well known to act as reservoirs for coronaviruses.

Viral Origins:

In the case of SARS, it is known that bats of the genus Rhinolophus were the reservoir of the virus, and that a small carnivore, the palm civet (Paguma larvata), may have served as an intermediate host between bats and the first human cases. The way in which the related COVID virus SARS-CoV-2 evolved and spread to humans is slightly less clear. There are close similarities between SARS-CoV-2 and coronaviruses found in bats and pangolins. Genetic comparisons suggest that the SARS-Cov-2 virus is the result of a recombination between two different viruses, one close to a bat virus, and the other close to a pangolin virus.

In December 2019, 27 of the first 41 people hospitalised in China (66%) passed through a “wet market” in the centre of Wuhan city in Hubei province. However, according to a study conducted at Wuhan Hospital, the very first human case identified didn’t frequent this market. Instead, a molecular dating estimate based on the SARS-CoV-2 genetic sequences indicated an origin in November. This raises questions about the link between the COVID-19 pandemic and wildlife.

Why this is a Global Problem:

It is easy to see this sort of thing as purely a Chinese problem but, as noted in my previous post, influenza pandemics have originated in the USA. Also, the agricultural businesses in China are major recipients of foreign investment.

Factory Farming

Influenza viruses that infect animals, including poultry and pigs, have intermittently spilled over into humans ever since we have been domesticating these animals. However, factory farm production allows the virulence of those viruses to be greatly increased just before they spill over. This phenomenon has been documented in Europe, Australia and the US more than it has in poor or emerging economies. It is the mechanism that gave rise to the Swine Flu pandemic in 2009.

Industrial farming is only part of the problem, however. Activities such as logging, mining, road-building, rapid urbanisation, and wars are destroying natural ecosystems, and creating the conditions that making switching of viruses between animals and humans far more likely.

Jane Goodall, the well known conservationist, has said that humanity will be “finished” if we fail to drastically change our food systems in response to the COVID pandemic, and the climate crisis.

The connections between intensive farming and disease outbreaks were examined by the FAIRR global investor network in a new report. It showed that more than 70% of the biggest meat, fish and dairy producers were in danger of increasing the risk of future zoonotic pandemics due to lax safety standards, and closely confined animals. The also noted the overuse of antibiotics, with the associated risk of increased antibiotic resistance.

This video from Vox shows how environmental destruction led to outbreaks of Ebola and West Nile Virus.

Conclusion:

The current pandemic is awful. As of today, there have been 11,418,475 documented cases of COVID-19, and it has killed 533,958 people, but it won’t, hopefully, last forever. What will last forever however, if we don’t change our ways, is the risk of a further pandemic: perhaps with another coronavirus that is even more infectious than SARS-CoV-2, and has the mortality rate of SARS (11% instead of 1%).

Medicine

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