Will the Ebola virus go airborne? | Hacker News Reader

Will the Ebola virus go airborne?

nature.com

65 pointsetiam58 comments

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.

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.

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.

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".

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.

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.

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.

> 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.

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.

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.

Life, uh, finds a way.

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!

Often these types of articles go in one ear and out the other of people with irrational fear of the unknown or are incapable of understanding the way a researcher might discuss the topic. I feel this is often the case simply because those spreading misinformation love to use very charged words that incite a lot of emotion while those in authority to speak on the subject use terms with strong meaning in science but have much less impact in regular speech.

This is a good example. The article's quotes use plenty of words like "remote chance" or "highly unlikely" which don't seem to drive home the point that its "so nearly close to impossible its not worth humoring". Meanwhile, New York Time's publishes an article read my many more viewers with comparisons to the Plague, using terms like "hyper-evolution" and really ridiculous comparisons that are just taken out of context for the sake of fear.

Its no wonder you get such "stupid" responses on news article comments, the entire thing is written to rile up readers and get an emotional response while hiding the actual science.

Heck, even reading the two articles side by side you get very different stories of the same event (regarding the Ebola lab tests between Pigs/Monkeys in 2012). On NYTimes they indicate that Pig -> Monkey transference was possible then the Monkeys all had to be euthanized to "contain the outbreak". Meanwhile SA article states that the virus was never capable of going Monkey -> Monkey.

> Will the Ebola virus go airborne?

> Experts say the possibility remains remote.

Seems like the article is acknowledging Betteridge's Law of Headlines in the subtitle. Very convenient!

Just for reference (I did not know about it)

Betteridge's Law: "Any headline which ends in a question mark can be answered by the word no." [1]

[1] http://en.wikipedia.org/wiki/Betteridge's_law_of_headlines

"Betteridge's observation of some headlines that end in question marks"

This "law" fails many tabloid-style headlines, and other obvious cases.

eg.

"Where's the money?" (headline about corruption involving tax-payer money)

"Is Betteridge's Law of headlines ever worth invoking?"

"Manchester United: Will they ever return to form?"

Betteridge's Law of Headlines should really be referenced more often with clickbaity titles like this.

I wish either the title requirements or HN users with sufficient karma could allow/add a @SavedYouAClick-style tag to these stories that would list on the front page ("Will the Ebola Virus Go Airborne? [Probably Not]"), rather than having the Betteridge's Law of Headlines discussion in every such thread.

Agreed, that would be even better still.

Someone was collecting all the times it got references on HN. It was useful the first few times, after that it became a race to see who could post "FRIST", er, "BETTERIDGE" in each comment section.

This article, as well as the nytimes.com op-ed piece, misquote/misinterpret the 2012 Canadian study that supposedly showed transmission from pigs to monkeys via air.

From the text of the study:

"Under conditions of the current study, transmission of ZEBOV could have occurred either by inhalation (of aerosol or larger droplets), and/or droplet inoculation of eyes and mucosal surfaces and/or by fomites due to droplets generated during the cleaning of the room."

Also from the study:

"The experimental setting of the present study could not quantify the relative contribution of aerosol, small and large droplets in the air, and droplets landing inside the NHP cages (fomites) to EBOV transmission between pigs and macaques. These parameters will need to be investigated using an experimental approach specifically designed to address this question."

People need to be careful about how they read these academic articles. The authors of the two aforementioned news articles misinterpreted the findings of the study in a way that supports their personal viewpoints.

I do agree that this issue needs attention, but not misinformation.

Link to actual study: http://www.nature.com/srep/2012/121115/srep00811/full/srep00...

I mentioned this in a previous discussion on Ebola, but thought it might be worth repeating. Last week, the BBC broadcast a generally informative documentary about Ebola. The programme talks to survivors of the virus, to the staff of Médecins Sans Frontières (MSF) treating victims, to Peter Piot, the Belgian doctor who discovered the virus (and established that the disease was not airborne) and the medical staff seeking a cure. There are some harrowing scenes.

For UK viewers, it's available on iPlayer until Friday 19 Sept. 2014 http://www.bbc.co.uk/iplayer/episode/b04hcthj/

For everyone else, someone's uploaded it to YouTube, although the last 10 minutes are missing https://www.youtube.com/watch?v=bjuQofIleOg

Great article. Isn't it obviously that Ebola or any other deadly virus is unlikely to become highly contagious via air simply because we don't see mass airbourn infections very often. (Do we ever see them?) If such mutations were likely, then we would see them. Massive plagues, wiping out something like %50 of the population would be common. There have been mass plagues in history of course, however, they are somewhat rare and often the result of poor sanitation. That's not as much of a problem in the modern world, although the third world still struggles with it. Worse yet, if airborn mutations were likely, then we would probably not see them at all, because evolution would not have brought about highly complex creatures. We would always get killed off by disease before making that far.

The flaw in this is that our mobility and density is unprecedented, so things that were not feasible for a startup plague in the past may now be feasible.

There are selection pressures against infections that kill the host. That may explain why highly quickly-lethal viruses are rare.

This is generally true, though occasionally parasitoid relationships are selected for (where there's a fitness advantage to killing off the host). Though these relationships typically only occur with an r selected host (many offspring, low probability of survival). Thankfully however humans are very heavily K selected (few offspring, high probability of survival).

>>we don't see mass airbourn infections very often.

Flu?

Common cold, also. Rhinoviruses aren't exactly rare.

The question of "will Ebola become airborne" is academically interesting, but not particularly relevant. The virus spreads just fine with its current mechanism: when you're excreting loads of virus via blood, saliva, sweat, feces and vomit, "body fluids" becomes a very effective means of transmission.

I live in San Francisco, and I can't tell you the number of times I encounter "body fluids" out in public. Last night, I nearly stepped in a pile of vomit on Market Street. Imagine that the vomit was from a man who recently returned from Nigeria. He'd been coming down with flu-like symptoms, and was on his way to his minimum-wage job as a prep cook, when he felt nauseous and threw up on the sidewalk. But it's a big city, and vomit on the sidewalk isn't uncommon. Nobody notices.

Over the course of several hours, dozens of people accidentally step in the vomit, getting it on their shoes. Some of those people go home, take off their shoes, and touch their face without washing their hands. The virus has now spread to unsuspecting people all over the city. Meanwhile, the prep cook is sweating over a pile of lettuce in a hot, cramped kitchen. His fever isn't helping matters, and it won't be long until he feels ill again, and visits the bathroom. He's supposed to wash his hands before returning to work, but he's not feeling well, so he doesn't do the greatest job. Back to work -- there are salads to prep!

It's the start of cold and flu season, so the dozens of people infected in the last day won't think twice when they come down with a fever. They'll go to work for a few days with what they think is a cold (because most people do, these days), and spread body fluids in all the normal ways that people do: touching their faces, then shaking hands. Touching the office lunch without washing their hands. Coughing. Sweating. Throwing up in the bathroom -- how many people get sick during a workday? How many people disinfect the aftermath with bleach?

It will be a week or more before anyone realizes that there are people dying across the city from what looks like a bad fever -- why would anyone suspect Ebola in the US? By the time epidemiologists become aware that there's even a problem, the virus will have spread to hundreds of random individuals in one of the most densely populated cities in the world....

What really makes it "not particularly relevant" is the articles that have said it's just not that likely to hop an international flight and show up in the US.

Which is what people really care about. Is that all it takes, one infected person to get on a plane? Or is this really going to be a West African problem - a terrible one, maybe, but it still has way fewer casualties than the civil wars that are all too common in the area.

It's one thing for a doctor to say that we're losing the chance to contain this thing, if we don't commit more resources... It'd be another to have them offer a timeline where it starts to impact Europe or the Americas.

It _is_ rather frightening to imagine all the invisible ways this virus could spread if it makes it over to a major city in the states. However, my understanding is that usually, within only a few days of expressing symptoms such as fever, vomiting, etc., patients are on their death bed if their immune system hasn't kicked in. This makes it seem less likely that someone will return to work one or two days after first coming down with a fever due to Ebola.

>but not particularly relevant. The virus spreads just fine with its current mechanism

This strikes me as a rather weak argument. Just because something "works" doesn't mean evolution/gene mutation won't find a way to make it work more "efficiently".

I'm also wary of drawing parallels to anything we see in a "modern" country...sure flu etc is contagious too - beyond that they are barely comparable though.

I don't think the issue is whether mutation might make it work more efficiently, but the probability that this might happen.

To estimate that you need to understand the precise mechanisms of variability, and the likelihood that the genetic elements that create Ebola symptoms could combine with the genetic elements that make influenza and rhinoviruses so infectious.

Obviously there's no teleology in mutation. But as infected populations increase, so does the possibility of dangerous recombination.

How much it increases, and whether we're talking about lottery odds, poker odds, or coin toss odds, is something only virologists know.

But apparently there's a second order health problem. You don't just want to minimise the spread for obvious practical reasons - you also want to minimise it because the bigger the infected population, the bigger the risk of dangerous mutation.

> In fact, there’s almost no historical precedent for any virus to change its basic mode of transmission so radically.

almost no meaning "just" smallpox?

I suspect that this conclusion has more to do with lack of data, than what's actually occurring in nature. Although we've made a lot of progress over the last two hundred or so years in biology, there're still plenty of things that remain unknown.

as it is already infectious on the infected fluid contact, it just need to learn to hitch a ride in a micro-drops of fluid people breath out (like the flu virus, though in case of flu the virus learned to make people cough - it helps to shoot the micro-drops out)

At the present rate its going to be a disaster with or without airborne anyway.

https://en.wikipedia.org/wiki/Betteridge's_law_of_headlines

Are risks ever downplayed due to question marks in headlines?

Have we reached Peak-Betteridge?

Will we be following on after this with the weather?

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