Researchers have warned that ancient pathogens, frozen for millennia in glaciers, ice caps, and permafrost, could emerge due to global warming as the ice melts and pose a significant threat. The study says these “time-traveling” microbes if released from their dormant state, can cause ecological chaos, throw ecosystems out of balance, and lead to the extinction of numerous host species worldwide.
The melting polar ice could expose an incredible treasure trove of ancient microbes, including some deadly to humans and animals. The thawing permafrost and ice also threaten human health, potentially releasing dangerous diseases like smallpox or the 1918 influenza strain that killed tens of millions of people.
Researchers have discovered several pathogens from ancient permafrost, but the risk to humans is growing as polar regions warm up. For example, a recently uncovered corpse in Siberia contained the deadly anthrax bacteria, which can kill within 24 hours. In addition, the recent deaths of two children in Finland have been linked to exposure to anthrax spores.
A team of European scientists has published a paper in the journal PLOS Computational Biology warning that permafrost and ice are a storehouse of pathogens from the distant past. The researchers used a software called Avida to simulate the release of one type of ancient pathogen into modern biological communities and found that the results were alarming.
The researchers say these models show that the release of just a single dormant virus can trigger ecological disruption and potentially cause the loss of host species worldwide. The simulated pathogens can also re-infect other organisms, leading to further environmental damage and biodiversity loss.
The research builds on previous studies showing that microorganisms can be revived after lying dormant for a long time, such as the revival of a 30,000-year-old virus in 2014 that was discovered in permafrost in Siberia. The virus, known as Pithovirus sibericum, infects amoebas and is not dangerous to humans. Still, it suggests that viruses dangerous to human life might also be capable of surviving freezing for eons.
The researchers used a new algorithm for screening ancient DNA, called HOPS (High-Throughput Pathogen Screening), which has much higher sensitivity than existing algorithms such as MIDAS, metaBIT, and SPARSE and fewer false positives than Kraken. It is designed for use with large metagenomic datasets and can identify the presence of simulated and real ancient pathogens in complex samples with high reliability. It can also detect the re-emergence of long-frozen pathogens in natural populations with high accuracy, and it provides detailed visualizations and statistical data at every evaluation step. Scientists hope to use the tool in future studies to help understand how ancient pathogens behave in natural environments. The full paper is available online in the journal PLOS Computational Biology. It is freely accessible through the PLOS open access policy.
