Earlier today, in Osterholm: What We’re Afraid to Say About Ebola, we looked at an Op-Ed by Dr Osterholm, and an interview of Osterholm by Helen Branswell, which discussed the possibility that – over time – the Ebola virus could pick up mutations that would allow it to transmit more readily among humans.
As you might imagine, this has caused a bit of a stir this morning, even though the possibility had been briefly mentioned a week ago by the director of the CDC, Dr. Thomas Frieden (see CDC & WHO Press Briefings On Ebola).
Viral mutations are fairly common – particularly among single-stranded RNA viruses - but the vast majority of these mutations won’t significantly affect the virulence or transmissibility of a virus one way or another. Some mutations can even degrade a virus’s ability to replicate, transmit, or cause disease, while a relative few are likely to enhance one of those traits.
Since these are random events, Ebola hitting the right (or for us, the `wrong’) combination of mutations is on par with someone winning the lottery. It can happen, but it’s a long shot.
Still, if you buy enough tickets . . .
Only a couple of weeks ago the report in Science presented 99 genomes representing some of the thousands of those circulating in Sierra Leone this year. I say thousands because each infected person has a range of subtley different viral variants among the billions of viruses per millilitre of blood that all compete to be the champion. The words "mutant" and "ebolavirus" are now hard to avoid. And of course as soon as you talk mutations, you can only see one endgame - a virus that is easily transmissible and
turns us all into zombies.spreads across the world in a pandemic and kills as many as 80% of those it infects.
The bottom line, as succinctly expressed by Ian, is that despite the conventional wisdom of the not-so-distant past, Ebola clearly doesn't "need" to be airborne to spread efficiently.