Research shows how the world’s population has created an ideal breeding ground for infectious diseases

The way that many of us live has created the “perfect storm” for the evolution and transmission of infectious diseases like Covid-19 according to a researcher at the University of East Anglia.

A new editorial published today describes how the world’s vast population of people, pets and livestock has created an ideal breeding ground for infectious diseases which are passed between humans and animals.

It shows how we urgently need to control the transmission of pathogens such as SARS-CoV-2 by using vaccination passports, maximizing genetic variation in livestock, and reducing how much meat we eat.

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

Cock Van Oosterhout, Professor, UEA’s School of Environmental Sciences

Prof Van Oosterhout’s article shows how the world’s biomass of livestock is more than 10 times higher than that of all wildlife combined.

‘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.

But the genetic effective size of the world’s livestock is 80 times lower than the minimum viable population size of free-living species.

Prof Van Oosterhout said: “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.

“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, maximizing 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.”

Cock Van Oosterhout

‘Mitigating the threat of emerging infectious diseases; a coevolutionary perspective’ is published in the journal Virulence on May 7, 2021. This work was supported by the Earth and Life Systems Alliance (ELSA) of the Norwich Research Park.