The Covid-19 is back to its killing ways in Pakistan after a long break as the it killed three people and infected another 55 during the last 24 hours, showed the figures released by the National Institute of Health (NIH) on Wednesday morning. The death toll in the country climbed up to 30,623 while the number of total infections now rose to 1,573,452 after adding the fresh 55 cases. During the last 24 hours (Tuesday), 8,815 tests were conducted throughout Pakistan whereas the positivity ratio stood at 0.62 percent. The number of patients in critical care was recorded at 45. Climate change may boost Arctic virus spillover risk A warming climate could bring viruses in the Arctic into contact with new environments and hosts, increasing the risk of viral spillover, according to research published Wednesday.

Viruses need hosts like humans, animals, plants or fungi to replicate and spread, and occasionally they can jump to a new one that lacks immunity, as seen during the Covid-19 pandemic. Scientists in Canada wanted to investigate how climate change might affect spillover risk by examining samples from the Arctic landscape of Lake Hazen. It is the largest lake in the world entirely north of the Arctic Circle, and was truly unlike any other place Ive been, researcher Graham Colby, now a medical student at University of Toronto, told AFP. The team sampled soil that becomes a riverbed for melted glacier water in the summer, as well as the lakebed itself -- which required clearing snow and drilling through two metres of ice, even in May when the research was carried out.

They used ropes and a snowmobile to lift the lake sediment through almost 300 metres (980 feet) of water, and samples were then sequenced for DNA and RNA, the genetic blueprints and messengers of life. This enabled us to know what viruses are in a given environment, and whatpotential hosts are also present, said Stephane Aris-Brosou, an associate professor in the University of Ottawa biology department, who led the work. But to find out how likely they were to jump hosts, the team needed to examine the equivalent of each virus and host family tree. Basically what we tried to do is measure how similar these trees are,said Audree Lemieux, first author of the research. Similar genealogies suggest a virus has evolved along with its host, but differences suggest spillover.

And if a virus has jumped hosts once, it is more likely to do so again. Very unpredictable - The analysis found pronounced differences between viruses and hosts in the lakebed, which is directly correlated to the risk of spillover, said Aris-Brosou. The difference was less stark in the riverbeds, which the researchers theorise is because water erodes the topsoil, removing organisms and limiting interactions between viruses and potential new hosts. Those instead wash into the lake, which has seen "dramatic change" in recent years, the study says, as increased water from melting glaciers deposits more sediment.That going to bring together hosts and viruses that would not normally encounter each other, Lemieux said.

The authors of the research, published in the Proceedings of the Royal Society B: Biological Sciences journal, caution they are neither forecasting an actual spillover nor a pandemic. The likelihood of dramatic events remains very low,Lemieux said. They also warn more work is needed to clarify how big the difference between viruses and hosts needs to be to create serious spillover risk. But they argue that warming weather could increase risks further if new potential hosts move into previously inhospitable regions. It could be anything from ticks to mosquitoes to certain animals, to bacteria and viruses themselves, said Lemieux. It really unpredictable... and the effect of spillover itself is very unpredictable, it can range from benign to an actual pandemic. The team wants more research and surveillance work in the region to understand the risks. Obviously weve seen in the past two years what the effects of spillover can be, said Lemieux.

Credit: Independent News Pakistan-INP