Posted on 09/04/2014 12:43:46 AM PDT by nickcarraway
A study in the journal Science, released last week, shows that the Ebola strain spreading across Western Africa has undergone a surprisingly high amount of genetic drift during the current outbreak. Experts say the mutations could eventually make the virus harder to diagnose and perhaps treat with a new therapeutic, should one come along.
In yesterday’s Wall Street Journal, I wrote that in response to the crisis, the Obama administration has stressed that the disease is unlikely to spread inside America. We will certainly see cases diagnosed here, and perhaps even experience some isolated clusters of disease. For now, though, the administration’s assurances are generally correct: Health-care workers in advanced Western nations maintain infection controls that can curtail the spread of non-airborne diseases like Ebola.
But our relative comfort in the U.S. is based on our belief that our public health tools could easily contain a virus spread only through direct contact. That would change radically if Ebola were to alter its mode of spread. We know the virus is mutating. Could it adapt in a way that makes it airborne?
(Excerpt) Read more at forbes.com ...
I guess epidemiology has coopted the term. In the study of evolution it means separation of a gene pool from another, usually geographically, and explains the different racial groups on the planet, along with other three components of evolution (mutation, mixture, and natural selection).
Applied to ebola, it would explain different strains appearing in different countries, for instance, or an airborne strain developing in one area.
As for viruses mutating within a single person, yes, that is a big danger, because of the heavy viral load of this disease, but is only tangentially related to genetic drift as it has usually been understood.
See post 62 also.
You forgot the most potent and overlooked of all, believe it or not.
Earwax.
Unfortunately, that control is proving counter productive at this point. Had they mustered up enough fear and panic to get the resources to stop the spread of this early on it would have been far less disruptive and it would be stamped out by now.
Instead, their mediocre response has allowed it to spread to more than 3000 people with no signs of slowing down. And they still don’t have effective quarantines and they’ve only started to get funding for equipment.
When I’ve seen the more elaborately equipped medical personnel using self contained breathing apparatus and oxygen tanks when dealing with these patients and I compare the statements of ‘it’s not airborne just droplets’ with the reality of the docs in space suits...I ask myself what the folks with the oxygen tanks know that we don’t?
Thank you.
“who would catch the disease but get better”
They could be barely sick with the disease but still act as reservoirs of infections to weaker folks until their better antibodies boot up. These silent “typhoid marys” are what may be a threat to populations that have no qualms with behaviors where sharing body fluids is a common as breathing. The Lib progressives screamed about aids and discrimination....how would they ever handle a super ebola plague that forced the surviving populations into moral behaviors that would rival the apostles themselves?
We have the ten commandments for a reason and even if one discounts the spiritual(which I don’t!)...nature herself can apply a most brutal scourge upon froward humanity!
The rhetoric does not meet the reality we’re seeing daily.
Another question: if Ebola is that difficult to contract, why is research on the virus limited to Level 4 laboratories?
The information being offered is so wildly different from what people are seeing in the video and reading on news sites, one has to wonder who believes that the rhetoric is going to overcome the images.
The day I see nursing staff and physicians in an Ebola treatment ward wearing no more than a surgical mask, goggles and pair of nitrile gloves, is the day I’ll give the rhetoric another look, starting with published studies demonstrating the difficulty of becoming infected via fomites, droplets, etc.
I suspect I’ll be waiting a long while.
The definition of genetic drift is the same, it is just that the time scale of the process in viruses is very short compared to the time scale when discussing large organisms. Also, the viruses don’t trade genetic material with each other, which further accelerates the process of genetic drift, since frequency of alleles is not a measure of drift.
The recent Science paper with the sequencing data shows phylogenetic trees; one of the trees (figure 3) is rooted back in February. It shows a single source for the outbreak, but the virus has already separated into two distinct clusters in Sierra Leone and Guinea, and each of those clusters appears to have sub clusters.
http://www.sciencemag.org/content/early/2014/08/27/science.1259657.full
I believe that is why they perform contact tracing of known cases.
The major problems I see are still cultural. As far as I know, many people in the affected areas do not believe that Ebola is a real disease. Sick people do not go to the hospital because they believe that hospitals are killing people (for their organs, even). Getting people to understand the risks and take precautions is a challenge in that environment.
I wager you will have to revise that statement fairly soon, possibly within a few weeks, but certainly by the end of the calendar year.
You’re welcome.
These folks would not be reservoirs, as after a single viral reproductive cycle beyond any illness, all the virus left in them would be dead. What their genetic anomaly accomplishes is to make their cells “slick” to viruses, so that they cannot attach themselves and burrow into the cells to reproduce. Or, they are only able to attach to a small number of cells. And this minor infection only lasts until their immune system destroys them and the cells they occupy.
Unless viruses can get into cells, they die, because the blood is very hostile to them. A breakdown product of vitamin D, for example, erodes their protective viral coat, so they break apart.
They got the first clue of this from homosexual men who were repeatedly infected with HIV, but shortly thereafter had no HIV in them. And it was the same with their ancestors, who might have been infected with the black plague many times, but were a dead end to the disease.
Bottom line, they would not be reservoirs like Typhoid Mary.
Some things I won’t bet on, but my best guess is you are correct.
And that actually is fairly accurate. An airborne disease is spread because viruses or bacteria within a fluid are shed when the fluid evaporates, for instance during the act of breathing when there is a high pathogen concentration in the upper airways. Airborne particles can remain suspended for hours and are carried on the breeze--you do not have to be in the same room with an infected person to breathe contaminated air.
We both know that by that definition, Ebola is "airborne."
Ebola is not airborne by that definition or any other.
I agree that the general public has no concept of the varied degrees and definitions applied in medicine but honestly, that makes the lies by omission that much worse IMO. Instead of announcing the facts, they weasel out of it by saying "technically Ebola is not transmitted by droplet nuclei, the most effective means of airborne transmission."
I do not know what these supposed "lies by omission" are. As far as I can tell, health officials making public statements about Ebola are being as accurate as possible about the disease. There are many things that are not known about Ebola, and of course, it is impossible to make statements about what is not known. I see no problem with the MSF statement or the WHO pamphlet.
That's going to be a real comfort to those who sicken and die because they inhaled infectious droplets while crammed on a subway or in an amphitheater or wherever, shoulder to shoulder with an infected (and likely unaware) person and clueless of the risk. Patients who picked up three Ebola particles from the elevator button will be relieved to know that the authorities were "technically correct."
Ebola is spread by droplets, fomites, and direct contact with infected bodily fluids, none of which are airborne transmission. While it is true that someone could be in the path of a droplet (for instance, from a patient vomiting blood) and be exposed that way, that is not airborne transmission. It is transmission through direct contact with infectious fluid.
To illustrate why knowing the difference between droplet/fomite/direct contact transmission and airborne transmission is important, I have linked a video: Ebola patient escapes quarantine centre in search of food. In this video, a man escaped from the hospital and went to a local market looking for food. The people at the market recognized that he was an Ebola patient, and kept their distance (about 10 feet or so). However, they were curious, and gathered in large numbers outside of that distance. The only people who got near the man were wearing the full protective gear. I noticed that several people were running around spraying (probably bleach) wherever that man walked. That's to kill any virus that he might have spit or bled.
If Ebola were airborne, that incident would have potentially exposed hundreds of people--anyone downwind of him--and spraying bleach where he walked would have no effect whatsoever.
I simply don't know how to respond to this. How many common, everyday events meet the criteria of being less than 3 feet from someone coughing and sneezing?
First of all, coughing and sneezing are not Ebola symptoms. Second, I think most people try to avoid those who are coughing and sneezing. Third, it is very unusual to be within 3 feet of someone who is vomiting blood or is having diarrhea. I don't think I would approach anyone vomiting blood--would you?
Reasonably intelligent people are listening to the authorities pronouncements, watching video reports of physicians and staff clad head to toe in PPE contracting and dying of Ebola, and noticing the conflict. These people may not be scientists or medical personnel but they're smart enough to realize that it doesn't add up.
The physicians and other medical personnel are wearing full PPE while treating patients, but that doesn't mean they can't come into contact with someone who has Ebola and has not presented for treatment or with surfaces contaminated with virus (aka fomites) when they are not caring for patients. There are also issues with whether they are wearing the PPE properly.
I don't know how many people will die from this outbreak but I think it will be a lot, somewhere in the millions. Given what's happened to date I see no serious effort to implement effective epidemiological controls, eg enforced quarantine.
There is a lot going on--contact tracing, and so forth. I do not think this outbreak will extend into the millions. I think that as more people become educated about the disease and begin to realize that it is, in fact, real, they will be more likely to adhere to the infection control measures communicated by the authorities. The bottom line is that this disease is not spread so much by characteristics of the virus, but by human behavior.
If you look at the video I linked, it appears that people *are* getting the message about the virus--they *do* realize that it is real, and not some conspiracy against them.
Indeed.
If it were airborne, we’d already be in the midst of a pandemic unlike any ever seen.
Even before airplanes, that 1918 flu managed to sweep around the world pretty quickly, within months. These days, with rapid and efficient travel, there is just no way we could stop a highly infectious airborne disease.
That report is accurate. Ebola virus biology does not suggest that it can become airborne. Thank God, because if it were airborne, we'd be looking at deaths in the tens, if not hundreds, of millions right now.
I have to wonder if some of our behavior that protects us from infection is a cultural legacy from being survivors of some really bad pandemics in the past.
We won’t eat dead things unless we know they were killed while healthy. Africans eat dead animals they find in the forest.
There are other major behavior differences that would make a disease like Ebola have a difficult time establishing itself here the way it has in Africa.
What they know, and the rest of us in medical professions know is that the viremia in an infected patient--the quantity of virus in a given quantity of blood--is very high compared to other bloodborne diseases, but the number of virus particles needed to cause infection is very low, around 10. If you are working with a patient who has millions of viruses per milliter of blood, and a tiny drop of blood too small to be seen contains enough virus to cause deadly disease--well, you'd probably want to cover up, too.
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