Posted on 10/26/2014 5:07:51 PM PDT by nomad
Bacteria thaws and ‘wakes up’ then.
As for viruses .... [quick google blurbs ....]
Can flu viruses survive winter in frozen lakes? - health - 29 ...
Nov 29, 2006 ... Evidence of viruses frozen in Siberian lakes prompts scientists to ... “Our hypothesis is that influenza can survive in ice over the winter and ...
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BBC News - 30,000-year-old giant virus ‘comes back to life’ - BBC.com
Mar 3, 2014 ... It was found frozen in a deep layer of the Siberian permafrost, but after it ... “If it is true that these viruses survive in the same way those amoeba ...
Thank you for your expertise too.
As for how to treat healthcare workers who return from hot spots, I fully support any honors that can be showered on them and maximum comfort/entertainment/dining/what-have-you during their isolation/quarantine.
Not in nature, but in the subway/Metro I think you might find something close.
...and a ridiculous number of people will remove a glove with their teeth.
One of the doctors was emphasizing the constant washing of hands....so sounds like you understand that issue.
Indeed—airplanes give it quite an extended, airborne range.
For all practical purposes, ejected droplets in my climate at ambient temperature in the winter form particulates. I have seen both spit and urine freeze on the way to the ground.
This also raises the question of viral longevity at low temperatures (subzero Fahrenheit), because for all practical purposes the ejected virus would be contained in a particle of ice.
With temperatures of -30F and wind speeds of 20 MPH considered a relatively normal day, those will likely get mixed in with the finely powdered snow which is normal here.
The joke is that the snow doesn't melt, it wears out on its way to Minnesota. In reality, it sublimates, which would eventually leave the little virons naked and freezing, stuck on a surface somewhere.
Keep in mind that solar angle is low (and so is UV), and that daylight hours are down to eight or so in midwinter. There is plenty of shade.
This raises questions, should an outbreak make its way here, of how long the virus would remain viable in such environs. Similar concerns have been raised by people in slightly milder climates, and I think they have raised a valid question.
As far as I know, there is no data which could conceivably predict that, but lingering 'frozen particulate fomites' could present a hazard to emergency personnel (especially near hospital entrances) and to the casual passerby in any location where the virus has been shed.
We become acclimated to such temperatures fairly readily (kids ride their bicycles in the snow in that weather), although the relatively dry air often wreaks havoc with sinuses and air passages.
The combination of irritated pharyngeal mucosa and readily inhalable frozen particulates is an unknown, but may present a hazard that cannot be extrapolated from tropical data.
Only in static air. Settling velocity can be overcome by wind speed and direction, keeping a droplet suspended.
We do. Dogs.
It remains to be seen if dogs can transmit the virus to humans or not. If they can we have big problems.
You can go "what if... what if?" all day long, and bring up any number of highly improbable scenarios. The fact is, freak occurrences happen all the time. Do you ever read the MMWR--the Morbidity and Mortality Weekly Report--posted on the CDC website? There are articles about the improbable events pretty frequently there. But in reality, risk management is about identifying the most likely event, analyzing it to determine if it represents a tolerable level of risk, and taking steps to mitigate the risk to a tolerable level. More people in the United States have developed fatal cases of rabies from organ donations than have gotten Ebola from blood transfusions.
A lot of these people aren’t assuming the strawman idea that a virus is magic, but a lot of everyday people are aware that in the face of unknowns, extreme caution is highly justified.
For the most part, the reason these are unknowns is that, until recently, most people weren't even aware of Ebola and they know nothing about it. It is not a strawman to point out that many of the... beliefs, for lack of better word... they express about Ebola are not attributes of any virus. For instance, the insistence that Ebola can somehow penetrate properly used PPE. No virus can do that. Therefore, it is a magic belief. Or the belief that Ebola can go airborne--which, if people knew anything about viral biology, they would understand is nearly impossible. And so on. Ebola really is not a supernatural entity that has all of the fantastic powers attributed to it, it is a virus that isn't even that hardy and certainly isn't very transmissible.
Thanks for the ping!
Viruses are challenging, and so are bacteria. We are fighting a never ending war with them. The antibiotics, antivirals, and vaccines we make to fight them are never 100% effective, and those few survivors can mutate to be resistant to the drugs or vaccines.
At least it means job security for us scientists.
Correct on both counts.
One of the problems with Ebola is that while we know some definite ways to become infected, we don't know all ways to become infected. (We know how much it takes (in terms of exposure) to become infected, but we do not know how little it takes to become infected.)
In the outbreaks so far, it is relatively easy to attribute infection to known means, which might be standing in the way of discovering other, less obvious, means of infection.
The unknowns have the potential to wreak havoc.
In one study, some 2% of the cases had uncertain incubation periods, possibly because the means of infection was not clear.
Whether those cases were infected by fomites, droplets carried on the wind, or an unknown human or animal carrier is just not known.
Pigs may present a similar problem, not just because they are a food animal, but because of increasing feral populations.
Ebola is an RNA virus.
Knowing how fragile RNA is, and the wide range of stability of proteins, I doubt that virus would be able to survive in those conditions. When you work in a lab, for instance, extracting RNA from Ebola viruses for PCR analysis, you go through a pretty ornate ritual to remove from the environment anything that could damage the samples. You wash the glassware with a special detergent, and rinse it with water that has been processed to remove anything that can damage RNA. You wash down all of the bench surfaces with a chemical to destroy anything that might damage RNA. You buy disposable lab supplies that are certified RNase and DNase free. You dedicate lab equipment for the purpose of analyzing RNA, and you never contaminate that equipment by using it to analyze any other type of biological molecule. People who work with RNA are extremely paranoid about anything that can destroy it, because it is so fragile. Your skin is saturated with enzymes that kill RNA, and those enzymes tend to be all over. Even when you put RNA into a special stabilizing solution, it has a shelf-life--about one month at -20C. When you put the purified samples in a -70C or -80C freezer, they last indefinitely--but once you remove them, you have to complete your analysis on them, because the RNA is not stable enough to freeze the leftovers for further analysis.
Proteins range in stability, but even the extremely stable proteins do not survive multiple freeze-thaw cycles. Changes in temperature are very destructive to any biological molecule.
Another RNA virus is rabies, which is endemic across the US. I have never heard of a case where rabies was transmitted by droplets of frozen saliva. Certainly, if rabies could transmit in that fashion, we'd have a lot of cases where someone out tramping through the snow in the winter kicked up a powder, or brushed their shoe, or otherwise made contact with virus-laden bits of ice. If rabies could transmit in that fashion, rabies would be a huge problem because of its endemicity. No one would know they'd been exposed, and so wouldn't get the prophylactic treatment. But rabies is not transmitted like that--the only way to get rabies is through direct contact with the saliva of an infected animal. All it has to do is enter through a break in the skin.
Usually we are lucky to have more than one or two thaws in a winter. Maybe global warming is cause for hope..
Rabies is a poor comparison, especially when you consider that a human would have to cut the trail of an infected animal and the odds of that are pretty slim, and even more so when you consider the odds of that particular patch of snow being contaminated.
My curiosity with Ebola, though, lies in the concept that humans congregate unlike the more territorial rabies carriers, and share space. Those shared spaces would have a significantly higher possibility of fomite contact, frozen or otherwise, and cold has been shown to preserve the virus. I even cited ER entrances as an area of possible concentration, due to the nature of the traffic there.
While winter is ertainly not at -70C ambient, but I have been in -40 (same temp either scale) and colder weather numerous times, and yes, life goes on despite the cold. I have seen a month here where the high temperature for the month was zero Fahrenheit (on one day, for about an hour), so this isn't the more temperate winter of much of the lower 48 I am talking about. Our snow sublimates during the winter, but seldom melts until spring.
Maybe where you live, the human population density is so low that humans and rabid animals never cross paths.
Here, the rabid animals are right in cities and towns.
The possibility is extremely remote, but *if* an Ebola patient were to show up at a hospital in ND in the dead of winter, and they were vomiting, the hospital would (I hope) be sanitizing the area—regardless of whether Ebola is suspected. There are plenty of nasty viruses that can be present in vomit.
The cold conditions that were shown to preserve the virus were in the controlled conditions of a laboratory. Laboratory freezers and fridges are made so as not to have temperature fluctuations, because those fluctations are very destructive to biological molecules. Winter in ND might be unrelentingly cold, but it does not remain at a stable temperature. Besides that, even in extremely cold temperatures, many enzymes are active, including the RNA destroying enzymes that are ubiquitous in the environment. For storage, viruses are suspended in special pH buffered solutions.
I have attempted to store proteins in a -20C freezer. I had boiled the proteins and added chemicals meant to stop any enzymatic reaction. Yet my proteins became degraded within a month. I can go on and on about the difficulty of preserving biological substances in a lab—the bottom line is that there is little reason to think an inherently unstable virus can somehow be durable in an uncontrolled environment. The temperature changes, the pH changes, variations in humidity, fragility of RNA, and so on, make it very unlikely that it will survive.
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