Wuhan Coronavirus
Pandemics are fascinating in so many ways, so every time one potentially pops up, I read a little more. I'm going to share some information.First off, if you want some historical background, this is a terrific book that I highly recommend: Pale Rider: The Spanish Flu of 1918 and How It Changed the World. A third of the world infected, deaths of 50-100 million people. Fatality rates are incredibly difficult to calculate because many deaths come from secondary infections, which is part of the reason for the wide range.
The case-fatality rate of the Spanish flu was 2.5%, according to the CDC (1918 Influenza: the Mother of All Pandemics). If you want to go into serious rabbit hole territory, here's an article about how case-fatality rate is calculated: The Time Required to Estimate the Case Fatality Ratio of Influenza Using Only the Tip of an Iceberg: Joint Estimation of the Virulence and the Transmission Potential.
The case-fatality rate of SARS was 17%, which is one of the reasons it didn't get very far. That high of a fatality rate severely limits the ability of a virus to spread, because the people who get infected have a limited window to transmit the virus.
At 2.5%, on the other hand, the Spanish flu was well-suited to infect a huge number of people, and the sheer number infected made even a 2.5% fatality rate incredibly high in terms of deaths. Plus, there were an untold additional number who died from secondary infections.
So far, the case-fatality rate of the Coronavirus is 3%. Certainly, that's a little worrying, although it's also true that containment ability worldwide has improved since SARS, where almost everything went wrong. Lessons learned, etc.
Birds were the host of the 1918 flu, but bats hosted SARS, and it's strongly believed that bats are the host of this current virus as well.
Why are bats such excellent disease reservoirs?
I thought you might ask that: Why Bats Are Such Good Hosts for Ebola and Other Deadly Diseases?
You know some of the reasons (they live in incredibly close proximity, they fly long distances), but here's an excerpt that blew my mind:
Even though bat genomes contain many of the same ingredients as other mammals, bats use them differently. In particular, the bat genes coding for proteins that detect and repair damaged DNA are much more prevalent than expected...
...DNA damage repair genes are frequent targets for invading viruses, which could be what is applying the evolutionary pressure. The findings also mesh with the anecdotal observation that bats rarely (if ever) develop tumors—perhaps because the repair genes can outpace any malignant growth.
...Newer, still-unpublished findings suggest that unlike in humans or mice, where defenses such as anti-tumor and anti-viral genes are activated only in response to a threat, in bats these genes seem to be perpetually turned on. That activity keeps levels of any harbored viruses simmering below the point at which they could cause harm. In other words, evolution has conspired to turn bats’ surveillance mechanisms up to 11.
As for why, Wang suggests a link with flight, which boosts a bat’s metabolic rate to a level many times higher than when it is resting. Such sustained energy production generates stress that can damage cells and DNA if it isn’t quickly detected and repaired.
So perhaps initially, those damage-repair proteins got turned way up to combat the damage caused by bats doing what bats do, which is flying around every night. If true, the ability to carry lethal viruses might have come second, as a sort of coevolutionary accident, Wang says.
All right, I've kept you long enough, but there's one more link to share: a real-time tracking of confirmed infections. A pandemic scoreboard, if you will: Wuhan Coronavirus Global Cases (by Johns Hopkins).
[UPDATE: Here are some surreal photos taken in Wuhan: Coronavirus: Photos From Wuhan Under Quarantine.]
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