A recent study, published in BMJ Global Health, reveals that pathogens once confined to isolated animal populations have triggered escalating epidemics, forming a concerning trend likely to worsen.
In the past four years, the world witnessed how viruses crossing species can swiftly escalate into a global crisis, as seen with the rare 'perfect storm' of COVID-19. International researchers argue that the world has entered an alarming era of heightened vertebrate animal-to-human infections.
The Rise of Viral Epidemics
In the period from 1963 to 2019, an analysis of historical data conducted by biotech company Ginkgo Bioworks reveals that outbreaks caused by four devastating viruses originating from animals increased by almost 5% annually.
Deaths surged at a remarkable rate of 8.7% each year. Projections based on this alarming trend suggest that by 2050, fatalities from these four diseases alone could be at least 12 times higher than the records for 2020.
Many modern viral epidemics stem from populations of wild or domestic animals carrying pathogens without causing them harm, silently passing them from generation to generation. If the virus evolves to enter a human body, any interaction between humans and the animal host can lead to a zoonotic spillover event, introducing pathogenic pioneers into our population.
With access to an extensive infectious disease outbreak database, Ginkgo Bioworks examined the frequency and severity of zoonotic outbreaks reported by the World Health Organization.
Focusing on animal-borne viruses like SARS coronavirus 1, filoviruses (Ebola), Machupo virus (causing Bolivian hemorrhagic fever), and Nipah virus, the researchers identified 75 events spilling over into human populations in 24 countries. Filoviruses proved to be the deadliest, causing over 15,700 deaths in 40 outbreaks during the studied period.
Despite the fragmented appearance of events across decades, researchers argue that these epidemics do not result from random activities but indicate a rising trend. If the observed trend persists, it is expected that these pathogens could cause four times as many spillover events and 12 times more deaths in 2050 than in 2020, excluding monumental cases like COVID-19.
Governments, spurred by the response to rising death counts during deadly pandemics, might consider expanding infrastructure and technology for enhanced surveillance of potential animal virus outbreaks in the future.
Spillover Events Deadlier Due to Climate Change
Spillover events involve a virus adapting to a new species. For successful transmission, the virus should not harm its primary host species significantly, and the primary species serves as a reservoir.
Transmission requires close contact between the primary and secondary hosts, overcoming barriers like incompatibility and the new host's immune response. Spillover events are complex processes involving adaptation and transmission dynamics.
Human activities, such as encroaching into wild habitats and causing population relocations through widespread habitat loss and climate change, have significantly increased the chances of these encounters. Zoonotic infections have been the primary cause of modern epidemics.
The escalating severity and spread of zoonotic spillovers necessitate addressing root causes like the climate crisis and healthcare gaps and enhancing global cooperation to mitigate the impact of inevitable future pandemics, which threaten to burden humanity further.
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