The 1918 influenza pandemic was the deadliest event in human history (50 million or more deaths, equivalent in proportion to 200 million in today’s global population). For more than a century, it has stood as a benchmark against which all other pandemics and disease emergences have been measured. We should remember the 1918 pandemic as we deal with yet another infectious-disease emergency: the growing epidemic of novel coronavirus infectious disease (Covid-19), which is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This virus has been spreading throughout China for at least 2 months, has been exported to at least 36 other countries, and has been seeding more than two secondary cases for every primary case. The World Health Organization has declared the epidemic a Public Health Emergency of International Concern. If public health efforts cannot control viral spread, we will soon be witnessing the birth of a fatal global pandemic.
[SARS-Co-V2] RNA sequences closely resemble those of viruses that silently circulate in bats, and epidemiologic information implicates a bat-origin virus infecting unidentified animal species sold in China’s live-animal markets. We have recently seen many such emerging zoonoses, including the 2003 bat-coronavirus–derived SARS (an earlier severe acute respiratory syndrome, caused by a closely related coronavirus), which came terrifyingly close to causing a deadly global pandemic that was prevented only by swift global public health actions and luck. Now, 17 years later, we stand at a similar precipice. How did we get to this point, and what happens next?
We must realize that in our crowded world of 7.8 billion people, a combination of altered human behaviors, environmental changes, and inadequate global public health mechanisms now easily turn obscure animal viruses into existential human threats.We have created a global, human-dominated ecosystem that serves as a playground for the emergence and host-switching of animal viruses, especially genetically error-prone RNA viruses, whose high mutation rates have, for millions of years, provided opportunities to switch to new hosts in new ecosystems. It took the genome of the human species 8 million years to evolve by 1%. Many animal RNA viruses can evolve by more than 1% in a matter of days. It is not difficult to understand why we increasingly see the emergence of zoonotic viruses...With Covid-19, are we seeing a replay of 1918? Although we did not “witness” the beginning of the 1918 pandemic, evidence suggests that wherever it began, it silently spread around the world, causing mostly mild cases but also mortality of 0.5 to 1% or higher — a rate that was initially too low to be detected against a high background rate of death from unrelated respiratory illnesses. Then it suddenly exploded in urban centers almost everywhere at once, making a dramatic entrance after a long, stealthy approach. We are now recognizing early stages of Covid-19 emergence in the form of growing and geographically expanding case totals, and there are alarming similarities between the two respiratory disease emergences. Like pandemic influenza in 1918, Covid-19 is associated with respiratory spread, an undetermined percentage of infected people with presymptomatic or asymptomatic cases transmitting infection to others, and a high fatality rate.
More at the link. Posted as a companion piece to the previous post with the "bats for sale" video.
N95 respirator!
ReplyDeleteI-)