Comment by themgt | Hacker News Reader

Comment by themgt | Hacker News Reader

I really see the strong, immediate pushback against this idea as mainly an attempt to calm the lay audience. Ebola has been airborne in other species before, and it's very nearly airborne in humans - this is certainly not a virus like HIV where even unprotected sexual intercourse has a low infection rate - we've got a huge number of infected doctors and healthcare workers, and there are calls for this to be treated like SARS:

"Infection control concerning EVD is not working, especially when more than 240 [now 300] healthcare personnel have been infected, and more than 120 workers have died. Guidelines used to control SARS in 2003 should be used, not "contact and droplet protection of 1-2 meters," as is still recommended by WHO.

Personal protective equipment (PPE) for contact and airborne infections should be used because of a) respiratory symptoms, b) a big distance -- up to 9 meters -- for droplets when coughing and sneezing (Bourouiba et al. J Fluid Mechanics 2014;745:537-563.), c) re-aerolization from the environment, bed clothes etc., d) long survival of the virus outside the body, and e) high lethality.

Healthcare workers (HCW) and helpers should be protected with PPE as they were during the SARS epidemic."

http://www.promedmail.org/direct.php?id=20140914.2773490

The real question is more like, will Ebola mutate to be more airborne than it already is?

The article addresses the so-called airborne nature of Ebola in other species and calls into question whether or not it was truly airborne in those instances. Furthermore, "very nearly airborne" is not a fair characterization. Bodily fluids transmit the disease, and Ebola's particular ability to make people spew lots of virus all over the place from every available orifice seems to be the primary way to spread. The odds of getting droplets in the eye, on a small cut on your skin, etc... as a healthcare worker are very high if someone is spraying virus-laden blood all over the place. But this is not what we're talking about with a truly airborne virus. In the case of an airborne virus like influenza, you have infection via the upper respiratory tract from viral particles that survive for extended amounts of time in aerosols suspended in the air. There is no evidence Ebola can or does spread in this manner.

Obviously nobody can predict the future, but viruses that infect via the airway are highly evolved to do so. The article touches on it a bit, but doesn't get into the real specifics. I'm going from memory here, but I recall that in things like the common cold and influenza, the viral proteins have specific humidity, pH, and temperature requirements in order to dock with receptors in just the right part of the airway in order to maximize infection. You don't get that without significant evolutionary pressure which as far as I can tell is totally absent in the current environment. The virus is easily spreading via direct contact with body fluids, so even if it develops an ability to spread by air, this offers little advantage over the plain old bodily fluid route.

That's all well and good but a slew of actual virologists disagree with this, citing examples such as no viruses affecting humans ever changing from being spreadable via bodily fluid/direct contact to becoming aerosol. This includes all viruses that have ever been known to affect human beings.

So, yes, while it is theoretically possible, it is extremely unlikely and really not worth discussing because no good can come from it.

What are the harms of assuming it is an airborne virus? This seems like a case where, as of today, global leaders are not scared enough. A bit of misinformed public hysteria could be just what politicians need to act.

What are the harms of assuming it is an airborne virus?

Oh, I donno, maybe panicked and unneeded responses to that hypothetical scenario when sober but aggressive responses to the present very real and already deadly situation are sorely need?

Just what comes to mind...

As the parent comment states, the question isn't will Ebola completely change it's infection vector to become airborne. Someone who has Ebola today can cough blood. If you become infected from someone coughing blood on you, does it matter that the infection came from the blood on their breath or from virus on their breath?

It seems that virologists are answering the wrong question and getting caught up on semantics, perhaps to prevent more hand wringing and panic.

Edit: removed statements about Reston, as they seem to have been remembered incorrectly from Hot Zone, the book about the primate-only Ebola outbreak in Virginia in the 90s.

You're confusing "spreads via an exchange of body fluids" (getting sneezed or coughed on by an infected individual would be included in this category) with "can survive and therefore spread via the air without any direct contact with bodily fluids" (walking outside of your house and breathing). You can't even call that a "semantic" distinction without coming off as really dishonest considering it's a totally different infection vector.

Anyway, I'm just arguing the points I've heard made by ACTUAL VIROLOGISTS. Read: PhDs who have been studying this exact behavior in viruses for many years. They've all said the same thing: theoretically possible, extremely unlikely.

I think we're actually in agreement.

To be fair tho, influenza is airborne, but you're not going to contract it by going outside and breathing, unless you're being breathed on by someone with the flu, or shaking their hand.

My point is that being breathed on, or even in close proximity to someone with Ebola is likely to result in you contracting the disease without actually touching them, as it is with influenza.

So, does it matter if the virus isn't 'airborne' in the strict medical sense if it is just as contractable as one that is from things like coughing?

It's a question, and not a rhetorical one.

Yeah, honestly I'm not qualified to answer that question. If I had to guess, one of the reasons why going airborne would be so bad is that it allows the virus to sprawl (geographically) much faster than it ever could otherwise (because it would be subject to wind etc).

Basically it could and would spread much faster and further if it were truly airborne. Also pretty much makes it impossible to contain because we can't just quarantine the earth's atmosphere.

In a few months it's flu season. A large part of the population will be sneezing and coughing. I don't wish to find out what happens when someone with ebola is introduced in such a system (e.g. infected doctor returning to the west). But your call for silence on the subject is nothing but short-sightedness.

It's not my call to make. It's the call of the numerous individuals who are infinitely more qualified than anyone reading and posting on HN. People that work at places like the CDC and have years of training and experience researching the effects of viruses like Ebola. They're all saying not to worry about that.

Even if they strongly suspected it will become airborne (based on something other than theory), do you think they'd just announce it to the public like "oh, hey, btw..."? Can you imagine the hysteria that would cause? Not "a bit" like another poster suggested. The effect of the hysteria could very well be worse than what the virus might cause on its own. It's really impossible to know, that is why we take measures to prevent getting worked into a highly irrational hysteria. These measures would include things like listening to qualified individuals and not ignoring the rational points they are trying to make to you.

I didn't actually find the article that reassuring. It boiled down to "it's unlikely to evolve true airborne transmission because it doesn't need to bother, it's plenty infectious through another route already."

Evolution doesn't ask itself whether it needs to "bother".

It doesn't ask itself that, but an airborne mutation wouldn't have a meaningful advantage, since the current virus is highly effective in spreading already.

exactly what the article was talking about.

The article's point is that it needs several mutations to become airborne and that those mutations have a cost; so unless the benefit of becoming airborne outweighs the cost, it won't happen.

Bear in mind that the traditional method of dealing with Ebola was simply to shut down travel in/out of affected settlements until the disease ran its course. This isn't working as well this time for a variety of reasons (I'll guess increased urbanization, better transportation, and problems with public information -- e.g. distrust of governments telling people to do sensible things).

What's probably far more likely is that a less lethal mutation will displace it. A disease that kills and kills quickly is maladaptive -- that's why the Ebola reservoir is believed to be bats which can catch it but not suffer ill effects.

Cost simply isn't how it works, the mutations are completely random. It has no direction other than chance as to if it becomes airborne. People can talk about it but a strain this virulent going airborne would be a disaster.

> Cost simply isn't how it works, the mutations are completely random. It has no direction other than chance as to if it becomes airborne.

A random walk on a gradient tends to go downhill, and becoming airborne is a long uphill trek.

Theoretically possible, but unlikely to the point I'm more concerned with other things.

Costs are exactly how it works, the "randomness" of mutations notwithstanding. Becoming airborne is not inherently an advantage for ebola - if the costs outweigh the benefits the virus with said mutation will not survive to replicate enough, thus the mutation will lose out long term.

Mutations are random, but to get a new "feature" you need many small mutations in the right direction. To accumulate the useful mutations you usually need that the intermediate mutations have some are useful alone. Most of the time these mutations have a side cost, so if the intermediate steps are not useful they are "discarded" because the non mutated members of the population outnumber the mutated population.

I think that most of us understand more about ostrich than about virus. Let's make a think experiment. How difficult is that ostrich become airborne? How many mutation they need? Is it possible? Is it dangerous?

I hope there is an ornithologist nearby, but I'll try:

* Stronger chest muscles

* More white meat in the chest muscles

* Longer wings

* Better feathers

* Lighter bones

* Shorter and lighter legs, to reduce weight

* Less brain? (less weight)

* Do you need some special brain areas to fly?

Ostrich is a case of neoteny ( http://en.wikipedia.org/wiki/Neoteny ), so many features can be possible changed at one. But it's a old case, so the genes for the features needed to fly are probably partially overwritten with garbage since a long time.

This is irrelevant. To be transmitted via an airborne vector does not require Ebola to mutate into a flying virus.

Life, uh, finds a way.

Not explicitly, but this is the nature of evolution; advantages against costs translate to greater success and replication.

You might say, for example, it would be advantageous if humans had feet that allowed them to climb trees faster or hold things with them. But that of course becomes a disadvantage for upright movement, etc. In this very article they discuss this concept in terms of costs for the Ebola virus to become airborne.

The link you quote is speculating on the needed guidelines based on "existing guidelines" failing - yet with these primitive conditions it's hard to see the infection of health care worker as being caused by these guidelines.

The level of protection being used by health care workers in the affected area seems to be determined by the fact that these are essentially the poorest nations in the world, with health care systems that barely functioned before the outbreak.

Reports indicate most Ebola clinics lack running water. Hopefully reports of donated masks and gloves indicate they will enough supplies soon. But until recently, many also lacked even rubber gloves.

I'm sure a good supply of PPEs would appreciated anyone could offer them, however.

> I really see the strong, immediate pushback against this idea as mainly an attempt to calm the lay audience.

Little off-topic, but reminds me of something I read once - if the government tells you to panic, it's probably nothing important and will blow over soon. When they tell you to keep calm and carry on, then it's probably the time to be really worried.

It's an interesting statement but if taken at its face value, we should have all been a lot more worried about December 21st, 2012 and the Mayan Calendar ending.

Maybe the Y2K hype softened most of those who would react.

Y2K wasn't hype: if we hadn't done the work, the outcome would have been moderately gruesome. (Not world-ending-apocalyptic gruesome, but not-getting-paid-for-a-month-and-the-stock-market-crashed gruesome.)

Indeed, it was largely due to Y2K resilience preparations that the Federal Reserve managed to keep running on 9/11:

http://www.dailykos.com/story/2014/09/10/1328813/-The-Astoni...

Upshot: it might look like hype, but sometimes it's actually the symptom of a bullet dodged just in time. (Which is why I hope that this time next year, when we look back at the Ebola outbreak, there will be plenty of folks saying "nope, it was overhyped fear-mongering".)

With that in mind, I remember being particularly interested in the way, during the gore/bush election recounts and court battles, the "rule of law" turn of phrase was suddenly injected into common (tv news) discourse and repeated ad nauseam.

I'd never heard that term being used in low-brow discourse before, and suddenly we heard it from every news source, every five minutes.

When has a modern government told its citizens to panic?

Terrorists!

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