Animal-To-Human Diseases Could Kill 12 Times More People By 2050

Most modern epidemics have been caused by pathogens that spread from animals to humans. These zoonotic diseases are predicted to increase as climate change and deforestation worsen

Disease epidemics transmitted from animals to humans could kill at least 12 times more people in 2050 than they did in 2020, according to a recently published study. These zoonotic diseases are known as “spillover events” when they enter the human population. Such spillovers could be more frequent in the future due to intensifying climate change and deforestation — both of which mean that humans come into contact with animals more frequently.

This prediction is, of course, dependent upon both animals and people still being alive on the planet in 2050 in sufficient numbers to share diseases, a situation that appears increasingly debatable due to the erratic natures of the intensifying climate catastrophe and mass extinction events gripping the planet.

The researchers, all of whom are employed by Ginkgo Bioworks, a Boston-based biotech company that specializes in using genetic engineering to produce bacteria with industrial applications for other biotech companies, analysed nearly 60 years of epidemiological data and found that the number of epidemics has been increasing by almost 5% every year between 1963 and 2019, with deaths up by 9%.

“If these annual rates of increase continue, we would expect the analysed pathogens to cause four times the number of spillover events and 12 times the number of deaths in 2050 than in 2020,” they wrote in their paper.

The team came to this conclusion after analyzing historic trends for four distinct types of viruses: Filoviruses (such as Ebola and Marburg), SARS Coronavirus-1 (which causes SARS), Nipah virus (associated with swelling of the brain), and Machupo virus (which causes Bolivian haemorrhagic fever). The team examined more than 3,150 outbreaks between 1963 and 2019, identifying 75 spillover events in 24 countries that killed 50 or more people. The events caused 17,232 deaths, with 15,771 caused by filoviruses and occurring mostly in Africa.

These viral diseases typically spread to humans through direct contact with infected animals, by vectors such as ticks or mosquitoes, through contact with an area where infected animals live, or by consuming contaminated food or water.

“Our evaluation of the historical evidence suggests that the series of recent epidemics sparked by zoonotic spillover are not an aberration or random cluster, but follow a multi-decade trend in which spillover-driven epidemics have become both larger and more frequent,” the authors note in their study.

The research team further pointed out that their estimates were “conservative” as they did not include COVID-19 in their study because it is “several orders of magnitude larger than other events”. The World Health Organisation has claimed that COVID was “likely” transmitted from bats to humans, although some scientists dispute this assertion.

The study’s authors note that although human-driven climate change is expected to lead to an increase in zoonotic diseases, its impact on global health is “difficult to characterise”. Further, the researchers note in their study that the “ultimate package of measures” designed to support pandemic preparedness is not clear.

“What is clear, however, from the historical trends,” the authors note, “is that urgent action is needed to address a large and growing risk to global health.”

Source:

Amanda Jean Meadows, Nicole Stephenson, Nita K. Madhav, and Ben Oppenheim (2023). Historical trends demonstrate a pattern of increasingly frequent and severe spillover events of high-consequence zoonotic viruses, BMJ Global Health 8:e012026 | doi:10.1136/bmjgh-2023-012026

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