I've seen numerous news claims that Ebola isn't easily transmitted. This rests on the idea that Ebola doesn't pass through the air the way flu does. Most such sources of facile reassurance fail to mention that it only takes eight virus particles to infect you.

Airborne Transmission of Ebola

Dr Cherry explains why CDC recommended protection measures are inadequate. In some animal studies Ebola jumped as if airborne. Recall that Marburg virus, a close relative of Ebola, is airborne.

Currently the CDC advises healthcare workers to use goggles and simple face masks for respiratory and eye protection, and a fitted N-95 mask during aerosol-generating medical procedures. Since so many doctors and nurses are dying in West Africa, it is clear that this level of protection is inadequate. Full face respirators with P-100 (HEPA) replacement filters would provide greater airway and eye protection, ...

The United States Army Medical Research Institute of Infectious Diseases conducted a monkey to monkey Ebola study in December 1995... three control Rhesus monkeys were kept in cages separated 10 feet from the infected monkeys. ... 2 out of 3 control monkeys died of Ebola ...

We know that airborne transmission of Ebola occurs from pigs to monkeys in experimental settings. We also know that healthcare workers like Dr. Kent Brantly are contracting Ebola in West Africa despite CDC-level barrier protection measures against physical contact with the bodies and body fluids of Ebola victims, so it only makes sense to conclude that some -- possibly many -- of these doctors, nurses, and ancillary healthcare workers are being infected via airborne transmission. It makes perfect sense that sick humans, as they vomit, have diarrhea, cough, and expectorate sputum, and as medical procedures are performed on them, have the ability to shed infectious Ebola particles into the air at a similar or higher level compared to Sus scrofa (wild boar) in the pig-to-monkey study.

Dr. Brantly acquired Ebola while strictly following CDC guidelines (simple mask, goggles, or face shield, gloves, gown, leg covering, shoe covers), so it is likely he became infected by inhaling contaminated droplet nuclei into his lungs or having them settle into his conjunctival (eye) sacs despite the use of CDC level protection against direct contact.

Aerosol-generating medical procedures such as surgical operations, endotracheal intubation, airway suctioning,and the operation of mechanical ventilators or BiPap devices place healthcare workers at very great risk, and I suspect even bathing patients is likely to generate infectious airborne droplets into the air. “Casual contact” or spending hours in the same room with Ebola patients also places medical personnel at significant risk, even with the CDC-recommended protective measures listed above.

... the current CDC guidelines are inadequate for preventing nosocomial transmission of Ebola from patients to medical workers.

It is not feasible for all medical workers in the United States to use "spacesuits" with a self-contained breathing apparatus air supply, as used in BL4 labs and at hospitals specially equipped for Ebola, but at a minimum, the American healthcare system should immediately upgrade respiratory / eye protection to full face mask respirators with P-100 filters for known or suspected cases of Ebola.

Although less airborne than Influenza, it is reasonable to conclude that the West African strain of Ebola is at times spread by airborne means since over 170 medical workers have been infected to date, with 81 dead. These victims were using CDC level protective measures against direct contact with the bodies and body fluids of Ebola patients, leaving airborne transmission as the remaining alternative mode. Simple face masks, and N-95 masks as well, are not good enough to filter out Ebola contaminated airborne particles, and they do not have silicon rubber seals against the face to prevent entrainment (leaking) of contaminated room air in clinic and hospital settings. Likewise, goggles and face shields are inferior in eye protection compared to full face respirators with P-100 filters. Since CDC-level respiratory/eye precautions for Ebola are inadequate for healthcare workers in West Africa, I assume they will also be inadequate in the United States. [emphasis mine]

This is what NOT GOOD ENOUGH looks like:

image source

Tags: Ebola, airborne transmission

Views: 431

Replies to This Discussion

Disease Modellers predict 10,ooo Ebola deaths before the end of the year, and "hundreds of thousands in the months after that".

Given this new information, we've set up automatic monthly donations to Doctors Without Borders. I urge you to consider the same.

Disease modelers project a rapidly rising toll from Ebola

Extrapolating existing trends, the number of the sick and dying mounts rapidly from the current toll—more than 3000 cases and 1500 deaths—to around 10,000 cases by September 24, and hundreds of thousands in the months after that.

Last week, the World Health Organization (WHO) estimated that the number of cases could ultimately exceed 20,000. And scientists across the world are scrambling to create computer models that accurately describe the spread of the deadly virus. Not all of them look quite as bleak as Vespignani's. But the modelers all agree that current efforts to control the epidemic are not enough to stop the deadly pathogen in its tracks.

But the modelers are hampered by the paucity of data on the current outbreak and lack of knowledge about how Ebola spreads.

“Before this we have never had that much Ebola, so the epidemiology was never well developed,”...

If the disease keeps spreading as it has, most of the modelers Science talked to say WHO’s estimate will turn out to be conservative. “If the epidemic in Liberia were to continue in this way until the 1st of December, the cumulative number of cases would exceed 100,000,” predicts Althaus.

In general, the chance of further spread beyond West Africa is small, Vespignani says, but the risk grows with the scale of the epidemic. Ghana, the United Kingdom, and the United States are among the countries most likely to have an introduced case, according to the model.

The models are only as good as the data fed to them; up to three-quarters of Ebola cases may go unreported.

“Quarantines and curfews tend to instill fear and distrust towards the whole of the outbreak response including health structures,” a representative for Doctors Without Borders told Science.

Paul Seabright, a researcher at the Toulouse School of Economics in France who has studied such measures, says they are an incentive for people to keep it secret if they have had contact with a patient. [emphasis mine]

Given the outpouring of charitable donations for ALS. I suggest an empathy gimmick. Show that you care about Ebola victims and the fear with which all West Africans now live by posting a picture of yourself bleeding from eyes ears and mouth. Like this.

I'm sure simulated blood is more effective than my poor Photoshop effort.

Frontline did a 26 minute video Ebola Outbreak.

Actually watching people facing Ebola is very different from reading about it.

Ebola model update - 5 days old.

image source

A Sept 2nd risk estimate for international spread of Ebola.

Results: We model the short-term growth rate of the disease in the affected West African countries and estimate the basic reproductive number to be in the range 1.5 − 2.0 (interval at the 1/10 relative likelihood). We simulated the international spreading of the outbreak and provide the estimate for the probability of Ebola virus disease case importation in countries across the world. Results indicate that the short-term (3 and 6 weeks) probability of international spread outside the African region is small, but not negligible. The extension of the outbreak is more likely occurring in African countries, increasing the risk of international dissemination on a longer time scale.

Assessing the International Spreading Risk Associated with the 2014...

BTW, one possible case just turned up in Australia.

A seriously ill Gold Coast man isolated and assessed for Ebola viru...

ProMED reports that

Bjorg Marit Andersen, MD, PhD
Professor in Hygiene and Infection Control
Speciality: Medical Microbiology
Former chief, Department of Hospital Infections
Oslo University Hospital - Ulleval
Gaustadveien 1a 0372 Oslo, Norway

recommends that healthcare workers should upgrade personal protective equipment to the standard used during the SARS epidemic.

3] Infection control is not working
Date: 14 Sep 2014
From: Bjorg Marit Andersen <bomarand@hotmail.com> [edited]


Infection control concerning EVD is not working, especially when more than 240 [now 300] healthcare personnel have been infected, and more than 120 workers have died. Guidelines used to control SARS in 2003 should be used, not "contact and droplet protection of 1-2 meters," as is still recommended by WHO.

Personal protective equipment (PPE) for contact and airborne infections should be used because of
a) respiratory symptoms,
b) a big distance -- up to 9 meters -- for droplets when coughing and sneezing (Bourouiba et al. J Fluid Mechanics 2014;745:537-563.),
c) re-aerolization from the environment, bed clothes etc.,
d) long survival of the virus outside the body, and
e) high lethality.

Healthcare workers (HCW) and helpers should be protected with PPE as they were during the SARS epidemic. The SARS epidemic was an infection control success by the healthcare system of some countries in Asia in 2003. But WHO should not repeat the same failure as was done during the early phase of the SARS-epidemic by using "contact and droplet isolation." Separate hospitals for EVD should be built, like in China (1000 beds in 8 days for SARS), and only patients with laboratory documented EVD should be cohorted. Suspected cases should be isolated separately.

HCW and helpers should be trained and especially observed concerning [putting] PPE on and taking [it] off. The observers should also use PPE. During the SARS epidemic, HCW were re-contaminated by not knowing how to take off PPE.

but

[The above directions are perfectly correct. Unfortunately, investigators are concluding that health worker infections are occurring outside the hospitals. - Mod.JW]

14 Sep 2014 Ebola virus disease - West Africa (164): Sierra Leone, infect. control, susp.

from http://www.promedmail.org/

Dr. Brantly acquired Ebola while strictly following CDC guidelines (simple mask, goggles, or face shield, gloves, gown, leg covering, shoe covers)

Dr. Brantly saw many patients who didn't obviously have Ebola, who may have been carriers, and without such protections, I'm pretty sure.  They were using the CDC protections when seeing the patients who were already sick with Ebola.  I saw a Dateline video on his case. 

Many sources claim that Ebola isn't contagious until symptoms appear. In the field this distinction may be difficult, so you may be correct about how Dr. Brantly got Ebola.  This article by national experts at the University of Minnesota Center for Infectious Disease Research and Policy goes into detail about the recommended level of protection, even with nonsymptomatic patients. Notice that with the patient's first cough or sneeze, the protection required jumps instantly.

While the personal protective equipment shown in photo costs more for a single suit, it's far better protection, more comfortable and more cost effective in the long run. The equipment now used takes 15 minutes to don and workers can only tolerate wearing it for 40 minutes. Also, removing contaminated suits is high risk.

COMMENTARY: Health workers need optimal respiratory protection for ...

We believe there is scientific and epidemiologic evidence that Ebola virus has the potential to be transmitted via infectious aerosol particles both near and at a distance from infected patients, which means that healthcare workers should be wearing respirators, not facemasks.1

The minimum level of protection in high-risk settings should be a respirator with an assigned protection factor greater than 10. A powered air-purifying respirator (PAPR) with a hood or helmet offers many advantages over an N95 filtering facepiece or similar respirator, being more protective, comfortable, and cost-effective in the long run.

We strongly urge the US Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) to seek funds for the purchase and transport of PAPRs to all healthcare workers currently fighting the battle against Ebola throughout Africa—and beyond.

We recommend using "aerosol transmissible" rather than the outmoded terms "droplet" or "airborne" to describe pathogens that can transmit disease via infectious particles suspended in air.

Caring for a patient in the early stages of disease (no bleeding, vomiting, diarrhea, coughing, sneezing, etc). ... an air purifying (negative pressure) half-facepiece respirator such as an N95 filtering facepiece respirator. This type of respirator requires fit testing.

Caring for a patient in the later stages of disease (bleeding, vomiting, diarrhea, etc). If we assume ... a standard patient room ... equivalent to either a full-facepiece air-purifying (negative-pressure) respirator or a half-facepiece PAPR (positive pressure), but standards differ in other countries. Fit testing is required for these types of respirators.

The control level (room ventilation) can have a big effect on respirator selection. For the same patient housed in a negative-pressure airborne infection isolation room (6-12 ACH), a respirator with an assigned protection factor of 25 is required. This would correspond in the United States to a PAPR with a loose-fitting facepiece or with a helmet or hood. This type of respirator does not need fit testing.

Implications for protecting health workers in Africa

... the minimum level of protection should be an N95 filtering facepiece respirator.

This type of respirator, however, would only be appropriate only when the likelihood of aerosol exposure is very low. For healthcare workers caring for many patients in an epidemic situation, this type of respirator may not provide an adequate level of protection.

Our risk assessment indicates that a PAPR with a full facepiece (APF = 50) or a hood or helmet (APF = 25) would be a better choice for patient care during epidemic conditions.

We recognize that PAPRs present some logistical and infection-control problems. Batteries require frequent charging (which requires a reliable source of electricity), and the entire ensemble requires careful handling and disinfection between uses. A PAPR is also more expensive to buy and maintain than other types of respirators.

On the other hand, a PAPR with a loose-fitting facepiece (hood or helmet) does not require fit testing. Wearing this type of respirator minimizes the need for other types of PPE, such as head coverings and goggles. And, most important, it is much more comfortable to wear than a negative-pressure respirator like an N95, especially in hot environments.

A recent report from a Medecins Sans Frontieres healthcare worker in Sierra Leone30 notes that healthcare workers cannot tolerate the required PPE for more than 40 minutes. Exiting the workplace every 40 minutes requires removal and disinfection or disposal (burning) of all PPE. A PAPR would allow much longer work periods, use less PPE, require fewer doffing episodes, generate less infectious waste, and be more protective. In the long run, we suspect this type of protection could also be less expensive.

A powered air-purifying respirator (PAPR).

I looked into PAPR's a bit as a possibility for my dog allergy.  I got the impression from what I read though, that a powered respirator is for people who don't have strong breathing ability, so they can't draw air well through the filters of an unpowered respirator.

Maybe this is wrong, though. 

I use a P100 respirator for my dog allergy.  It filters better than a N95 respirator.  But dog allergen and at least one kind of mold, aren't well filtered out by the P100 respirator. 

I found it very very difficult to breathe through an N-95 mask, and I have normal breathing.

I use 3M P100 2091 filters on my facemask, and they're easy to breathe through.

It is socially isolating, though.  People like to see the expression on one's face, and not much shows while I'm wearing the facemask.  My voice comes through muffled, so it's hard to get my meaning across.  And I get a certain amount of people muttering that I'm a nut for wearing the facemask, or staring at me.  Once recently someone called the police when I was waiting outside the bicycle store, while they worked on my bike.  I think it was mostly because I was wearing my facemask. 

It makes me look like a space alien with giant pink nostrils:

99.97% filter efficiency for particulates doesn't sound the same as a HEPA filter. Aren't virus particles much smaller than the particulates this is intended to remove? Nevertheless, it sounds more helpful than an ordinary surgical mask.

HEPA filters are supposed to remove 99.97% of particles 0.3 micrometers in size. 

Viruses are about 20-400 nanometers in diameter.  400 nm = 0.4 micrometers. 

But the Ebola virus isn't airborne in that sense - not floating around as isolated viruses in the air.  When people catch it through the air, it's in tiny droplets that someone might sneeze or cough out - much bigger particles than the virus itself. 

I posted a link earlier explaining that.  

In practice, the quality of HEPA filters varies a lot.  The big HEPA filter on the air cleaner I live next to, filters MUCH better than my facemask.  The facemask valves leak some, etc. etc. 

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