4 ms·

There's already limited evidence that some transmission is occurring via atomized saliva/mucous. A truly airbone variant could cause a "get in your bunker and r

There's already limited evidence that some transmission is occurring via atomized saliva/mucous. A truly airbone variant could cause a "get in your bunker and ride it out" kind of event.

freyrs3 12y ago
Might as well start worrying about an airborne mutation of HIV while we're at it. Wouldn't start heading for the bunker just yet.
danieltillett 12y ago
Yes Ebola can be transmitted that way, but it is an unlikely route. The way Ebola is constructed it is very unlikely to become airborne [1], but it could increase in natural reproductive efficiency (R0). We really have no idea of the R0 for Ebola right now as we don’t have the people on the ground recording what is happening in the community. Ebola does not have to become airborne for it to be a problem. Polio is not airborne and it has a very high R0 (5 − 7). The difference is polio is adapted for human-to-human transmission while Ebola is very unlikely to be. I don’t want to find out how well adapted Ebola can become. [1] Something that I have noticed about the discussion here is many people are unclear about what it mean for a virus to be “airborne” (this is not surprising since most people are not virologists). What airborne mean is that the virus is adapted to spreading via small mucosal droplets. The classic virus for this is rhinovirus (the most common cold virus). Rhinovirus infects the mucosal cells of the upper respiratory tract, it causes you to produce lots of mucus, it makes you sneeze a lot releasing this mucus in small droplets into the air, the virus is hardy enough to survive in the small mucosal droplets, and it doesn’t make you that ill so you still go to work where you can spread it around your co-workers. Doing all the things required the evolution of many interlocking adaptations in the Rhinovirus genome. Ebola's infection mechanism is nothing like Rhinovirus. While in theory it is possible that Ebola could acquire all the adaptions required to be spread efficiently by small mucosal droplets, it is really unlikely as there are so many changes required. This is why most experts think it is unlikely that Ebola will become “airborne”.
- TheOtherHobbes 12y ago
  Not everyone is convinced: http://www.cidrap.umn.edu/news-perspective/2014/09/commentary-health-workers-need-optimal-respiratory-protection-ebola http://www.cidrap.umn.edu/news-perspective/2014/09/commentar... Some health workers have been infected even though they were equipped with significant protection. Clearly infection rates in unprotected populations would be non-trivial, even without the kind of mutation that would make Ebola as infectious as a rhinovirus. Given that many public spaces in Western cities are more densely populated than equivalent spaces in Africa, and there are much greater numbers passing through them, I'm genuinely concerned this has the potential to blow up in a vey bad way. I'm not heading for the hills yet, but if case numbers begin increasing I'm going to consider it seriously.
  - throwaway5752 12y ago
    The linked article is making a nuanced claim in general about aerosol transmission in general, not a specific change in the structure of the Ebola virus.
  - pdabbadabba 12y ago
    I'm not a doctor or epidemiologist, but I think, as a matter of common sense, that there's a distinction between being an "airborne contagion" and being merely transmissible through saliva. We know that Ebola can be transmitted through saliva, but it does not cause any symptoms that would tend to aerosolize that saliva (coughing or sneezing). This would mean that you're not at all likely to get Ebola if you just happen to stand near an infected person, but we will still occasionally hear of people who seem to have been infected "through the air." These, one would think, would tend to be healthcare workers since they see patients at their sickest and may be performing procedures (e.g. intubation) that aerosolize saliva.
- yoshizar 12y ago
  Wasn't there strong circumstantial evidence that the Ebola Reston strain was spreading without any bodily contact? It was discovered in lab monkeys in Virgina and spread from room to room of monkeys without any direct contact between the monkeys. It's possible caretakers were spreading it, but it seemed more likely that the strain had gone airborne.
nostrademons 12y ago
Usually the progression of most diseases is toward easier transmission but lower mortality rates. Viruses that kill their hosts have a hard time becoming endemic. My prediction for Ebola is that it eventually becomes like norovirus (stomach flu): a common gastrointestinal ailment that is painful and inconvenient, but seldom lethal, and spreads easily through contaminated surfaces.
- danieltillett 12y ago
  Firstly, this might happen over millions of years, but this is unlikely to occur anytime in the short term. Many viruses that have been in the human population for a long time have quite high death rates in immune naive populations (think of small pox as an example). Secondly, the mechanism of transmission of Ebola is quite closely tied to the cause of death. To be transmitted it needs to turn you into a massive viral factory and then make you very “leaky” so the virus gets spilled out into the environment. Any mutations that decrease mortality are also likely to decrease the infectiousness of Ebola Thirdly, Ebola is starting off from a very high death rate. Even if there was a major decrease in the mortality rate (say it only kill 5% instead of 50 to 75% people), it would still be a huge problem.
  - thret 12y ago
    http://en.wikipedia.org/wiki/History_of_syphilis http://en.wikipedia.org/wiki/History_of_syphilis "The first well-recorded European outbreak of what is now known as syphilis occurred in 1495 among French troops besieging Naples, Italy.[3] From this centre, the disease swept across Europe. As Jared Diamond describes it, "[W]hen syphilis was first definitely recorded in Europe in 1495, its pustules often covered the body from the head to the knees, caused flesh to fall from people's faces, and led to death within a few months." The disease then was much more lethal than it is today. Diamond concludes,"[B]y 1546, the disease had evolved into the disease with the symptoms so well known to us today." It doesn't take millions of years for diseases to adapt.
    - danieltillett 12y ago
      Of course is doesn’t always take millions of years, but it can take millions of years and it is not something you should expect will happen quickly. Even in the case of syphilis it still took 50 years. The evolution of syphilis (to a slower disease course) is exactly what we should be most worried about happening with Ebola as it will then be more effectively spread - just because syphilis is not as quickly lethal as it once was it is not something that you want to catch and leave untreated.
throwaway5752 12y ago
People here are so inclined toward numbers that I fear people are latching basic reproduction rate (R0) without proper context. The transmissibility of a disease is not some kind of invariant property of the pathogen. It's not meaningful to talk about the R0 of Ebola in any kind of historic sense. Jungle/rural outbreaks are going completely different from urban ones, and this is a very different outbreak than previous ones. Very simply, if you have a 100% transmissible disease and are in a sealed room with 0 people until the pathogen is gone, your R0 is zero. If you're in a room with 100 people, it's 100. I guess I'm saying that I'd love a reliable citation for your claim. Changes in R0 aren't necessarily evidence of that, and those claims (especially airborne transmission) is just needlessly and baselessly worrying people.
tjradcliffe 12y ago
As others have pointed out, Ebola lacks a large number of important features that rhinoviruses, for example, have. It is possible given sufficient time Ebola will mutate in ways that generate those features. It is also possible, given sufficient time, Ebola will mutate into flesh-eating flying monkeys (admittedly, this is marginally less likely than becoming airborne.) Viruses--parasite and pathogens generally-are incredibly narrowly adapted to their preferred mode of attack. They have to be, because the chinks in the host's immune system are almost by definition incredibly narrow. If they weren't the host species would not have survived. This gives pathogens and parasites very little room to maneuver. They can't just arbitrarily bolt on new capabilities. They have relatively little genetic material to work with: 19 kilobases in the case of Ebola, which is less than the coding length of the majority of human genes (which can run comfortably into the hundreds of kilobases). So think of Ebola like an evil eight-bit micro-controller. It's only got 256 bytes to work with. It has been carefully programmed with a tiny attack program that depends on a very specific weakness in the target system that requires it be plugged into a USB port controlled by a particular chipset rev from a particular manufacturer. The claim "it might go airborne" is equivalent to the claim that such a chip, under millions of random mutations, might be able to infect systems via network ports while remaining the same in every other respect. This is not (provably) impossible, but it is of such low probability that I'm pretty sure anyone concerned about it should be in a state of panic regarding cows, coconuts, coronal mass ejections, and other far-more-probable causes of death if they want to make any claims to intellectual consistency.

There's already limited evidence that some transmission is occurring via atomized saliva/mucous. A truly airbone variant could cause a "get in your bunker and ride it out" kind of event.

freyrs3 12y ago

Might as well start worrying about an airborne mutation of HIV while we're at it. Wouldn't start heading for the bunker just yet.

danieltillett 12y ago

Yes Ebola can be transmitted that way, but it is an unlikely route. The way Ebola is constructed it is very unlikely to become airborne [1], but it could increase in natural reproductive efficiency (R0). We really have no idea of the R0 for Ebola right now as we don’t have the people on the ground recording what is happening in the community. Ebola does not have to become airborne for it to be a problem. Polio is not airborne and it has a very high R0 (5 − 7). The difference is polio is adapted for human-to-human transmission while Ebola is very unlikely to be. I don’t want to find out how well adapted Ebola can become. [1] Something that I have noticed about the discussion here is many people are unclear about what it mean for a virus to be “airborne” (this is not surprising since most people are not virologists). What airborne mean is that the virus is adapted to spreading via small mucosal droplets. The classic virus for this is rhinovirus (the most common cold virus). Rhinovirus infects the mucosal cells of the upper respiratory tract, it causes you to produce lots of mucus, it makes you sneeze a lot releasing this mucus in small droplets into the air, the virus is hardy enough to survive in the small mucosal droplets, and it doesn’t make you that ill so you still go to work where you can spread it around your co-workers. Doing all the things required the evolution of many interlocking adaptations in the Rhinovirus genome. Ebola's infection mechanism is nothing like Rhinovirus. While in theory it is possible that Ebola could acquire all the adaptions required to be spread efficiently by small mucosal droplets, it is really unlikely as there are so many changes required. This is why most experts think it is unlikely that Ebola will become “airborne”.

TheOtherHobbes 12y ago
Not everyone is convinced: http://www.cidrap.umn.edu/news-perspective/2014/09/commentary-health-workers-need-optimal-respiratory-protection-ebola http://www.cidrap.umn.edu/news-perspective/2014/09/commentar... Some health workers have been infected even though they were equipped with significant protection. Clearly infection rates in unprotected populations would be non-trivial, even without the kind of mutation that would make Ebola as infectious as a rhinovirus. Given that many public spaces in Western cities are more densely populated than equivalent spaces in Africa, and there are much greater numbers passing through them, I'm genuinely concerned this has the potential to blow up in a vey bad way. I'm not heading for the hills yet, but if case numbers begin increasing I'm going to consider it seriously.
- throwaway5752 12y ago
  The linked article is making a nuanced claim in general about aerosol transmission in general, not a specific change in the structure of the Ebola virus.
- pdabbadabba 12y ago
  I'm not a doctor or epidemiologist, but I think, as a matter of common sense, that there's a distinction between being an "airborne contagion" and being merely transmissible through saliva. We know that Ebola can be transmitted through saliva, but it does not cause any symptoms that would tend to aerosolize that saliva (coughing or sneezing). This would mean that you're not at all likely to get Ebola if you just happen to stand near an infected person, but we will still occasionally hear of people who seem to have been infected "through the air." These, one would think, would tend to be healthcare workers since they see patients at their sickest and may be performing procedures (e.g. intubation) that aerosolize saliva.
yoshizar 12y ago
Wasn't there strong circumstantial evidence that the Ebola Reston strain was spreading without any bodily contact? It was discovered in lab monkeys in Virgina and spread from room to room of monkeys without any direct contact between the monkeys. It's possible caretakers were spreading it, but it seemed more likely that the strain had gone airborne.

nostrademons 12y ago

Usually the progression of most diseases is toward easier transmission but lower mortality rates. Viruses that kill their hosts have a hard time becoming endemic. My prediction for Ebola is that it eventually becomes like norovirus (stomach flu): a common gastrointestinal ailment that is painful and inconvenient, but seldom lethal, and spreads easily through contaminated surfaces.

danieltillett 12y ago
Firstly, this might happen over millions of years, but this is unlikely to occur anytime in the short term. Many viruses that have been in the human population for a long time have quite high death rates in immune naive populations (think of small pox as an example). Secondly, the mechanism of transmission of Ebola is quite closely tied to the cause of death. To be transmitted it needs to turn you into a massive viral factory and then make you very “leaky” so the virus gets spilled out into the environment. Any mutations that decrease mortality are also likely to decrease the infectiousness of Ebola Thirdly, Ebola is starting off from a very high death rate. Even if there was a major decrease in the mortality rate (say it only kill 5% instead of 50 to 75% people), it would still be a huge problem.
- thret 12y ago
  http://en.wikipedia.org/wiki/History_of_syphilis http://en.wikipedia.org/wiki/History_of_syphilis "The first well-recorded European outbreak of what is now known as syphilis occurred in 1495 among French troops besieging Naples, Italy.[3] From this centre, the disease swept across Europe. As Jared Diamond describes it, "[W]hen syphilis was first definitely recorded in Europe in 1495, its pustules often covered the body from the head to the knees, caused flesh to fall from people's faces, and led to death within a few months." The disease then was much more lethal than it is today. Diamond concludes,"[B]y 1546, the disease had evolved into the disease with the symptoms so well known to us today." It doesn't take millions of years for diseases to adapt.
  - danieltillett 12y ago
    Of course is doesn’t always take millions of years, but it can take millions of years and it is not something you should expect will happen quickly. Even in the case of syphilis it still took 50 years. The evolution of syphilis (to a slower disease course) is exactly what we should be most worried about happening with Ebola as it will then be more effectively spread - just because syphilis is not as quickly lethal as it once was it is not something that you want to catch and leave untreated.

throwaway5752 12y ago

People here are so inclined toward numbers that I fear people are latching basic reproduction rate (R0) without proper context. The transmissibility of a disease is not some kind of invariant property of the pathogen. It's not meaningful to talk about the R0 of Ebola in any kind of historic sense. Jungle/rural outbreaks are going completely different from urban ones, and this is a very different outbreak than previous ones. Very simply, if you have a 100% transmissible disease and are in a sealed room with 0 people until the pathogen is gone, your R0 is zero. If you're in a room with 100 people, it's 100. I guess I'm saying that I'd love a reliable citation for your claim. Changes in R0 aren't necessarily evidence of that, and those claims (especially airborne transmission) is just needlessly and baselessly worrying people.

tjradcliffe 12y ago

As others have pointed out, Ebola lacks a large number of important features that rhinoviruses, for example, have. It is possible given sufficient time Ebola will mutate in ways that generate those features. It is also possible, given sufficient time, Ebola will mutate into flesh-eating flying monkeys (admittedly, this is marginally less likely than becoming airborne.) Viruses--parasite and pathogens generally-are incredibly narrowly adapted to their preferred mode of attack. They have to be, because the chinks in the host's immune system are almost by definition incredibly narrow. If they weren't the host species would not have survived. This gives pathogens and parasites very little room to maneuver. They can't just arbitrarily bolt on new capabilities. They have relatively little genetic material to work with: 19 kilobases in the case of Ebola, which is less than the coding length of the majority of human genes (which can run comfortably into the hundreds of kilobases). So think of Ebola like an evil eight-bit micro-controller. It's only got 256 bytes to work with. It has been carefully programmed with a tiny attack program that depends on a very specific weakness in the target system that requires it be plugged into a USB port controlled by a particular chipset rev from a particular manufacturer. The claim "it might go airborne" is equivalent to the claim that such a chip, under millions of random mutations, might be able to infect systems via network ports while remaining the same in every other respect. This is not (provably) impossible, but it is of such low probability that I'm pretty sure anyone concerned about it should be in a state of panic regarding cows, coconuts, coronal mass ejections, and other far-more-probable causes of death if they want to make any claims to intellectual consistency.