I am aware of all of this. What's interesting is that the report specifically identifies Human transference and the how and why of it. I wish I understood more about the actual science being discussed.
Some pathogens are limited in the cell type and location they infect. Influenza, for example, is generally restricted to respiratory epithelial cells, which explains why flu is primarily a respiratory infection and is most likely aerosol transmissible. HIV infects T-helper cells in the lymphoid tissues and is primarily a bloodborne pathogen with low probability for transmission via aerosols.
Ebola virus, on the other hand, is a broader-acting and more non-specific pathogen that can impede the proper functioning of macrophages and dendritic cells—immune response cells located throughout the epithelium.15,16 Epithelial tissues are found throughout the body, including in the respiratory tract. Ebola prevents these cells from carrying out their antiviral functions but does not interfere with the initial inflammatory response, which attracts additional cells to the infection site. The latter contribute to further dissemination of the virus and similar adverse consequences far beyond the initial infection site.
Direct injection and exposure via a skin break or mucous membranes are the most efficient ways for Ebola to transmit. It may be that inhalation is a less efficient route of transmission for Ebola and other filoviruses, as lung involvement has not been reported in all non-human primate studies of Ebola aerosol infectivity.27 However, the respiratory and gastrointestinal systems are not complete barriers to Ebola virus. Experimental studies have demonstrated that it is possible to infect non-human primates and other mammals with filovirus aerosols.25-27
Altogether, these epidemiologic and experimental data offer enough evidence to suggest that Ebola and other filoviruses may be opportunistic with respect to aerosol transmission.28 That is, other routes of entry may be more important and probable, but, given the right conditions, it is possible that transmission could also occur via aerosols.
The potential for transmission via inhalation of aerosols, therefore, cannot be ruled out by the observed risk factors or our knowledge of the infection process. Many body fluids, such as vomit, diarrhea, blood, and saliva, are capable of creating inhalable aerosol particles in the immediate vicinity of an infected person. Cough was identified among some cases in a 1995 outbreak in Kikwit, Democratic Republic of the Congo,11 and coughs are known to emit viruses in respirable particles.17The act of vomiting produces an aerosol and has been implicated in airborne transmission of gastrointestinal viruses.18,19 Regarding diarrhea, even when contained by toilets, toilet flushing emits a pathogen-laden aerosol that disperses in the air.20-22
Experimental work has shown that Marburg and Ebola viruses can be isolated from sera and tissue culture medium at room temperature for up to 46 days, but at room temperature no virus was recovered from glass, metal, or plastic surfaces.23 Aerosolized (1-3 mcm) Marburg, Ebola, and Reston viruses, at 50% to 55% relative humidity and 72°F, had biological decay rates of 3.04%, 3.06%. and 1.55% per minute, respectively. These rates indicate that 99% loss in aerosol infectivity would occur in 93, 104, and 162 minutes, respectively.23
In still air, 3-mcm particles can take up to an hour to settle. With air currents, these and smaller particles can be transported considerable distances before they are deposited on a surface.
To summarize, for the following reasons we believe that Ebola could be an opportunistic aerosol-transmissible disease requiring adequate respiratory protection:
- Patients and procedures generate aerosols, and Ebola virus remains viable in aerosols for up to 90 minutes.
- All sizes of aerosol particles are easily inhaled both near to and far from the patient.
- Crowding, limited air exchange, and close interactions with patients all contribute to the probability that healthcare workers will be exposed to high concentrations of very toxic infectious aerosols.
- Ebola targets immune response cells found in all epithelial tissues, including in the respiratory and gastrointestinal system.
- Experimental data support aerosols as a mode of disease transmission in non-human primates.
Risk level and working conditions suggest that a PAPR will be more protective, cost-effective, and comfortable than an N95 filtering facepiece respirator.
http://www.cidrap.umn.edu/news-pers...ers-need-optimal-respiratory-protection-ebola
