>>Is there potential for transmission in public transit; if someone with Ebola were to shed blood or sweat and another passenger came in contact with the blood or sweat?
So is there the potential? What often happens is people come with scenarios that are, say, like this. So you're in a taxi and they say, well, what if the person who was in the taxi before me was a sick person who was bleeding or had vomiting, and then [the taxi driver] dropped them off at the hospital. And the passenger had contaminated the seats with vomitus or stool. And then I get into the taxi and I put my hand on the seat, and then I touch my eye. Could I get Ebola like that? Yes, you could get Ebola like that.
Is that really what our major concern is? Those things are probably very [rare].
>>How much do we in fact know about transmission?
We don't really have lots of sound data of what period people start shedding virus and from what tissues. And so that would be incredibly valuable data. What we do have is the epidemiological data, and when we put that together from past outbreaks, it really appears that most infections occur from very sick people late in the course of their illness.
One thing that happens, and it's very clear from both human as well as non-human primate data, that in Ebola, the sicker you are, the higher your viremia — the level of virus in your blood. Conversely, if you're not very sick, you have a very low level of virus in your blood, you're not particularly infectious.
And when you think about it, the virus, it's not jumping off the wall, it has to get from one person to another. And so if I have Ebola right now – which I don't, by the way, I haven't been in West Africa for over a month. But if I had Ebola right now, even if I said, “OK, I have a fever and a headache, but I still feel well enough to have this conversation,” your risk of getting Ebola from being around me and probably even shaking my hand, is extremely low to nil, because I just don't have very much virus.
It's clearly not transmitted from casual contacts. Going and shaking hands with a person who's not sick does not transmit Ebola. And then someone will ask: Well, what if they had a sick family member at home and they didn't wash their hands? So you can always come up with something where you say, “Yeah, that could do that.” And the example I use is, OK, there's a plane that's flying overhead, and could that plane crash now into this building and kill us? It could, but it's probably not the most likely thing we need to worry about.
So we know how this is spread. This is spread from direct contact with sick people, and that's where we need to focus. And is there somebody somewhere who had indirect contact through one of those things, from being in the wrong taxi or kind of the wrong situation? It probably happens and we don't know it, but it doesn't happen very often, and it's not where we need to focus our public health approach..
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This sure looks like a case of "Yes, But...I don't want to consider vehicular Ebola fomite infection" to me..
As in, "We don't want the public to think about it for fear of what the public's fear will do to out international public health logistics."
This is very much a case of needing "public trust" to function and the international public health authorities treating the 'irrational public' as something to be despised and lied to in order to maintain control...
...which is the surest way to lose public trust in the "smart phone Internet" era. It isn't irrational to fear something that will kill you and your loved ones horribly.
All major health organizations value ‘public trust’ over the public.
It’s how they roll.
Basically stay the hell away from people who are visibly ill, bleeding, puking, s*****ting, coughing, etc. and don't go where they've been if you can avoid it. We knew this. If they're not doing those yet, they're not shedding much of a viral load.
There are no absolutes here. It is not possible to avoid all risk save by avoiding all people.
Once Ebola appears in your area, wear nitrile gloves, waterproof shoes or booties and N95 masks, and cover your eye area with goggles to keep you from rubbing your eyes with your hands when outside your home. Then spray a bleach solution on your gloves and rinse the footwear off in a bleach solution before re-entering your house, take off the gloves and the goggles, spritz the goggles ditto, take off the footwear and enter your house. And don't let the kids outside save for vaccination.
Dr. Bausch just said the fomite contamination threat forms a continuum rather than being a pure yes/no issue, just as the PPE manufacturer said last week that the non-exhalation airborne transmission threat forms a continuum based on distance. People can certainly contract Ebola at distances greater than three feet from large droplets emitted from the mouth, trachea and esophagus of victims by coughing and sneezing, but the danger of that drops off dramatically after three feet. It just doesn’t end entirely at three feet. The stuff can waft around for dozens of feet and 10-15 minutes, but its viral load will be going off-scale very fast.
What I got from Dr. Bausch’s statement was his reiteration of the viral load issue. The greater and denser the Ebola viral load is in anything, the more dangerous it is. Sure the LD/50 load is only 10 whatevers. More is more, and less is less. You might contract Ebola from a small viral load in dried saliva secretions on a doorknob 4-5 days after the emitter touched it, but the odds of that are low. But if the dude hawked up a clot of mucus onto the doorknob 20 minutes ago, you are in big trouble from touching it unless you are wearing glove and goggle PPE.
Living with uncertainty is hard. That is no reason to despair or worse, refuse to do what you can to protect your family and yourself.
I’m searching for short-term stop-gap solutions short of quarantine pending availability of vaccines, and things are looking better.
Consider things like a younger set of Wal-Mart greeters outside their stores, using remote thermometer sensors on prospective customers and accompanied by armed guards. No one with a detectible above-normal temperature will get inside. And dark glasses will be required inside due to all the U/V lamps. Ditto for grocery stores, public access buildings, etc.
There hasn't been much research done into fomite transmission (nor, for that matter, transdermal infection).
Simply put, the reason is that those infected have some other vector which can be blamed.
We are where it took Kimberly Bergalis' infection with AIDS via a dentist's drill to admit AIDS could be caught from fomites, too.
Rare? Sure, because other vectors or behaviours could be blamed for the infection.
The bottom line is that we do not know how many people were initially infected by fomite contact and then went on to become more infected by other means already known to be effective.
Without knowing that, we cannot assess the risk, only acknowledge it.
Needless to say, there is economic (and other) pressure to downplay the threat of fomites.
While Dr. Bausch’s replies seem very informed and “to the best of his extensive knowledge” kind of answers, I am reminded of the principles of failure analysis (fault trees) that were employed by NASA during the early Apollo development. While a NASA engineer could honestly state that the likelihood of failure of a given component was “1 in a million”, that was the wrong question to ask.
The proper way to look at the Apollo situation was to look at the overall Apollo system, and how all the parts depended on the other parts. This meant that a unit’s failure rate could not be considered in isolation, because its actual likelihood of failure depended on what was happening “upstream” from it. The net result was that an aggregate rate of failure might end up as 1 per 100 missions, because some $2 part that no one gave a second thought to was actually the weak link in a long chain (the chain only being as strong as its weakest link).
Relating that to Dr. Bausch’s answers, the question isn’t what are the odds that I will sit in a taxi that the previous occupant vomited in who had ebola. I’m sure that from our current vantage point, the odds are trivially small. But, the proper question is a very complex fault tree comprising what are the odds that the disease will work its ways to our borders (by intention or by accident) and then what are the odds that (not I but) some hapless American will be in the wrong place at the wrong time to unintentionally contract the disease. And if that happens, what are the odds that a typical American, or maybe an American at the fringes of society can be truly contact-traced in the proper manner, given that many people I know meet thousands of strange people per week as they traverse airports, downtown attractions, restaurants, etc.
The key to the problem is statistics, which is not the way a doctor is going to generally be thinking about the problem. In fact, I’m thinking that the fact that ebola only needs 1 to 10 virions to infect a person is in some significant measure causing the confusion on “how did this infection occur?” How many microparticles are exhaled during a sick sneeze? What are the odds that just one of those thousands stay afloat long enough to land on someone else? And what are the odds that it contains several virions? Asked that way, the perception of the transmission process gets revised quickly.
We don't really have lots of sound data of what period people start shedding virus and from what tissues. And so that would be incredibly valuable data.
I haven't found much at all regarding viral shedding phases, etc. I find a lot of assumptions based on epidemiological findings but not much data. Until now it hasn't been a real public health issue anywhere in the world, much less in first world countries, so very few researchers spent time on it. As often happens, the ZMAPP drug came about as a result of research into cystic fibrosis therapies.
So here we are, facing a serious viral disease about which little is known but much is assumed. I suppose a lot of research facilities are scrambling to start the studies that will eventually provide data on issues like transmission, immune responses, etc.