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Humans and livestock create the "perfect storm" for pandemics

Humans have created the “perfect storm” for the emergence of pandemics like COVID-19, according to a new study from the University of East Anglia. The report from Professor Cock Van Oosterhout describes how the world’s vast population of people, pets, and livestock supports an optimal breeding ground for zoonotic diseases that are passed from animals to humans.

The research highlights the urgent need for measures to control the transmission of pathogens such as SARS-CoV-2, including vaccination passports and reducing meat consumption.

“We humans have been living in a non-sustainable way over the past few centuries. We now have a vast population size – not only of humans but also of domesticated animals and livestock,” said Professor Van Oosterhout.

“This makes an ideal breeding ground for the evolution and transmission of zoonotic infectious diseases that jump from an animal to a human host.”

According to the study, global livestock biomass is more than 10 times higher than that of all wildlife combined. At the same time, the genetic effective size of the world’s livestock is 80 times lower than the minimum viable population size of free-living species.

Professor Van Oosterhout explained that the genetic effective size determines how much genetic variation can be maintained in the population, and this genetic variation is critical to counter the evolution of infectious diseases.

“The combination of high livestock biomass and low genetic variation has tipped the co-evolutionary balance with zoonotic pathogens.”

“Habitat destruction, illegal wildlife trade and other human activities have brought many species into contact with each other – and this facilitates a spill-over, spillback and hybridization of the pathogens.”

“Given that we are in close contact with our domesticated animals and livestock, there are many opportunities for the spill-over of viruses from animals to humans, and spillback from humans back to animals.”

“Altogether, these conditions have created a perfect storm for the evolution and transmission of zoonotic infectious diseases.”

According to Professor Van Oosterhout, COVID-19 has shown us that humans are not immune to the evolutionary processes that drive the adaptations of pathogens.

“We urgently need to reset this co-evolutionary imbalance and control the transmission of pathogens such as SARS-CoV-2 by using vaccination passports, maximising genetic variation in livestock, and reducing our consumption of animal protein. We also need to be aware of pathogen reservoirs, both locally and globally.”

“It is time that we start to recognize that our health, the environment, and our global economy are all closely interlinked. Pathogens like SARS-CoV-2 will continue to evolve when allowed to infect humans, anywhere in the world. In turn, this poses a threat to the human population at large, also in countries that have the infection under control.”

“Our society is facing significant threat, and we all need to do what we can both at an individual and societal level to improve our long term prospects as a species. These changes needs to be implemented globally to effectively combat pandemics.”

The study is published in the journal Virulence.

By Chrissy Sexton, Staff Writer

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