posted on Aug, 7 2014 @ 02:05 AM
SPECULATION: The current virus might be transmitted by indirect means, not just close personal contact with an infected patient's body
FACT: Here is what I see as the problem. There is a distinction between droplet transmission and airborne transmission. The CDC describes droplet
transmission as follows:
I.B.3.b. Droplet transmission:
Droplet transmission is, technically, a form of contact transmission, and some infectious agents transmitted by the droplet route also may be
transmitted by the direct and indirect contact routes.
The maximum distance for droplet transmission is currently unresolved, although pathogens transmitted by the droplet route have not been
transmitted through the air over long distances, in contrast to the airborne pathogens discussed below. Historically, the area of
defined risk has been a distance of less than 3 feet around the patient and is based on epidemiologic and simulated studies of selected
infections 103, 104.
Now the CDC proceeds to say:
Droplet size is another variable under discussion. Droplets traditionally have been defined as being greater than 5 μm in size. Droplet
nuclei, particles arising from desiccation of suspended droplets, have been associated with airborne transmission and defined as less than 5 μm in
Observations of particle dynamics have demonstrated that a range of droplet sizes, including those with diameters of 30μm or greater, can remain
suspended in the air. The behavior of droplets and droplet nuclei affect recommendations for preventing transmission. Whereas
fine airborne particles containing pathogens that are able to remain infective may transmit infections over long distances, requiring AIIR to prevent
its dissemination within a facility; organisms transmitted by the droplet route do not remain infective over long distances, and therefore do not
require special air handling and ventilation.
So infectious droplet range is under question. (I'll come back to this.)
The CDC defines airborne transmission as follows:
I.B.3.c. Airborne transmission:
Airborne transmission occurs by dissemination of either airborne droplet nuclei or small particles in the respirable size range
containing infectious agents that remain infective over time and distance (e.g., spores of Aspergillus spp, and Mycobacterium tuberculosis).
Note that airborne transmission involves droplets too. So the distinction hinges on infectious droplets under 5 micrometers that remain infective
over time and distance.
First, let's cover the distance issue.
In April of this year, a study published in the Journal of Fluid Mechanics, addressed this very issue:
Droplets from coughs and sneezes travel farther than you think
It is common knowledge that when we cough or sneeze, we should cover our mouth and nose with a tissue to prevent germs from becoming airborne. Now,
new research from the Massachusetts Institute of Technology suggests this instruction is more important than ever; they found that
droplets from coughs or sneezes can travel up to 200 times farther than previously thought.
The team found that, contrary to previous beliefs, each droplet from a cough or sneeze is connected through interaction with a gas cloud.
Droplets that are 100 micrometers in diameter were found to travel five times farther than past estimates, while droplets 10 micrometers
in diameter were found to travel 200 times farther. In addition, the team found that droplets less that 50 micrometers in size are often
able to stay airborne long enough to enter ceiling ventilation units.
That certainly calls into question the three feet language I've see thrown about in the media. Moreover, the question of "what happens to pathogens in
the droplets carried by the gas cloud" is still under investigation.
Now, let's cover the time issue.
SURVIVAL OUTSIDE HOST: The virus can survive in liquid or dried material for a number of days (23). Infectivity is
found to be stable at room temperature or at 4°C for several days, and indefinitely stable at -70°C (6, 20). Infectivity can be preserved by
So Ebola can live outside a host in liquid
material at room temperature
for several days
Finally, let's discuss the size of the Ebola virus:
It is an elongated filamentous molecule, which can vary between 800 - 1000 nm in length, and can reach up to14000 nm long (due to concatamerization)
with a uniform diameter of 80 nm.
Incidentally, 1 micrometer equals 1000 nanometers, which is relevant when you consider the less than 5 micrometer airborne distinction described
Now all of this is not to say the current Ebola crisis we are facing is in fact airborne.
But it is meant to warn against DEFINITIVE pronouncements that it is not or can't be.
edit on 7-8-2014 by loam because: (no reason given)