Viral spillover risk

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Key findings-

• As per the new study, climate change could shift the species range of certain viral vectors and reservoirs northwards, and the High Arctic zone could become fertile ground for emerging pandemics.
• To study the possibility of a viral spillover, researchers from the University of Ottawa collected sediment and soil samples from Lake Hazen in Canada – the largest High Arctic lake by volume in the world, and the region’s largest freshwater ecosystem.
• Then they undertook DNA and RNA sequencing to reconstruct the lake area’s virus composition. 
• They estimated the spillover risk and found that the chances of a virus moving to a new host increases with runoff from glacier melt, treated by them as a proxy for climate change. 
• As temperatures increase, the melting of glaciers increases as well, and there is a greater possibility for previously ice-trapped viruses and bacteria to find new hosts.
• In this study, while it was found that the risk of viral spillovers increases with changes in the environment at a particular location, driven by global warming, this by itself does not guarantee a higher possibility of a pandemic occurring via viruses here. “ 
• This is because there is another important link in the process. As long as viruses and their ‘bridge vectors’ – that act as hosts and lead to their spread – are not simultaneously present in the environment, the likelihood of dramatic events probably remains low.

What is viral spillover risk?

• Spillover infection, also known as pathogen spillover and spillover event, occurs when a reservoir population with a high pathogen prevalence comes into contact with a novel host population. 
• The pathogen is transmitted from the reservoir population and may or may not be transmitted within the host population. 
• Due to climate change and land use expansion, the risk of viral spillover is predicted to significantly increase.
• Viruses are some of the most abundant entities on earth, but they need to infect a host’s cell in order to replicate. 
• According to the research, these virus/host relationships seem relatively stable within superkingdoms, the major groupings of organisms. 
• However, below this rank, viruses may infect a new host from a reservoir host (in which it usually resides) by being able to transmit sustainably in a novel host – a process defined as ‘viral spillover’.

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