[yeison]

According to this article, it seems like a lot of health care workers are catching the disease. Even the westerners who are familiar with the transmission mechanism of the disease. Therefore, isn't possible that we are underestimating how easily the disease can spread?

[timr]

"isn't it possible that we are underestimating how easily the disease can spread?"

Yes, though the number of health care workers catching the disease in West Africa is more indicative of the total lack of basic medical supplies there, than anything else. Last that I heard, the MSF has a very low rate of transmission to medical staff because they're properly outfitted and strict about decontamination protocols.

That said, too many people are repeating the "it isn't airborne" line as if it has great significance. Ebola doesn't need to be "airborne" -- it's contagious enough, simply because it's very difficult for human beings not to come into contact with "bodily fluids", particularly when they're caring for sick people.

The fact that Ebola "isn't airborne" is comforting from the perspective that it isn't likely to spread to large numbers of people in public spaces. But even so, it's more than infectious enough to cause an epidemic.

[towski]

This will be the first time humans have ever underestimated nature

[skmurphy]

The CDC model http://stacks.cdc.gov/view/cdc/24900 assumes that a sick person in a hospital or containment unit spreads the disease to 0.02 people per day (vs. 0.3 people per day "in the wild") if you have enough Ebola patients in the hospital for a long enough period of time you are going to see a lot of medical personnel infected. For example if this epidemic lasts another 6-12 months in West Africa (which is the CDC's current estimate) some hospitals or containment facilities may operate for 100-300 days with personnel exposed to new sets of Ebola patients every five to ten days.

I am surprised that there has not been more written about recruiting survivors to work in the facilities (on the theory the they are much more likely to be immune to re-infection at least on many basic cleaning and patient care tasks (not inserting IV's or doing complex procedures).

Edit/Update Medscape did a detailed write-up on Ebola at http://emedicine.medscape.com/article/216288-overview and includes this note on recovery time, which may explain why even those who survive may take months to recover:

In those patients who do recover, recovery often requires months, and delays may be expected before full resumption of normal activities. Weight gain and return of strength are slow. Ebola virus continues to be present for many weeks after resolution of the clinical illness.

[danieltillett]

Very interesting modelling work here by the CDC. The transmission rate has been estimated using the following three assumptions:

(i) No additional imports of infection.

(ii) Patients maintain the pattern of either going to a hospital early in infectious period, or at home or in a community setting such that there is a reduced risk of disease transmission (includes safe burial when needed).

(iii) Maintenance of effective isolation and barriers-to-infection at hospitals and at home or in a community setting such that there is a reduced risk of disease transmission (includes safe burial when needed).

Both (ii) and (iii) are already wrong so I don’t know how much faith we can put in the modelling accuracy.

[ghshephard]

You can put faith in the modeling accuracy, while at the same time noting that given the current conditions, it does not have great predictive ability.

[danieltillett]

The modelling is actually really good and almost perfectly matches what has actually happened. The problem is they are expecting that things are about to change to fit the three assumptions. If we model the situation using the current conditions on the ground then things look a lot less rosy.

[maxerickson]

MSF seems to be effective in training people:

http://www.msf.org/article/ebola-workers-risk-tragic-reality...

(of their ~3000 staff in the region, 14 have been infected, they believe most of those infections have taken place outside of their hospitals)

The doctor in the article, who decided to check someone with potential Ebola exposure for a fever with his bare skin, was not being extremely careful.

[danieltillett]

What the MSF leave out of this article is the number of their staff that are actually treating Ebola patients. Without knowing this critical piece of information we can't really know what the transmission rate is to staff.

[maxerickson]

Sure, it isn't deeply informative. Their other releases discuss treating hundreds of confirmed cases (and a multiple of that of people admitted to their treatment centers), so I guess we can presume that there are at least a similar number of personnel dealing with that treatment (even if they are severely limiting actual patient contact, they are still dealing with a lot of waste and so on). The religious hospital in the article had 10 personnel involved in treatment and 10 of them got infected. That's enough to at least direct your attention towards what the groups are doing differently (it could well come down to limiting care based on the ability to carry it out very carefully rather than training).

[ghshephard]

As long as the doctor (A) did not have any cuts on his hand and (B) washed it immediately after checking the skin temperature, and (C) the individual was not symptomatic (No Diarrhea, No vomiting) the risk is pretty minimal. Probably more risk from being coughed on.

(Note - doctors should be washing hands continuously regardless - when I went in for a checkup in Kaiser/Mountain View a few years ago, Doctor washed his hands upon coming in the room, washed his hands after checking my heartbeat with a stethoscope, and then washed them a third time before leaving the room. This was to check someone who had no symptoms whatsoever. I asked him about it, and it was Kaiser policy - he said he washed his hands about 20 times an hour. )

[maxerickson]

So go ask that doctor how he would interact with you if he believed there was a chance that you had an infectious disease with a high mortality rate. Or if he was in a room that didn't even have a sink.

[adevine]

I read another article that explained how Ebola is very infectious (meaning that very few virions are needed to establish an infection), but not particularly transmissible (i.e. it's not airborne, and thus much less contagious than something like the flu or measles).

While westerners are becoming infected, I don't think it's that hard to see how the extremely poor health care facilities in West Africa would make it very difficult to follow proper protocol, even if you knew what you were doing.

[crpatino]

Even in US settings, compliance with basic hygiene protocols may be below 50% [1]. This happens mostly in overcrowded facilities where personnel has been cut to run at or near capacity most of the time.

The most salient factor is indirect contact. Health care workers are aware that they must wash their hands after having contact with a sick patient, but it is extremely hard to remember to take similar steps after touching any surface such patient might have touched himself, even if it looks clean to the bare eye.

[1] http://prosperouswaydown.com/ebola-game-changer/

[ghshephard]

" Health care workers are aware that they must wash their hands after having contact with a sick patient"

Take that a step up - Health Care workers must wash their hands after having contact with any patient and before touching any patient (and themselves for that matter).

http://www.cdc.gov/features/handwashing/

It takes 20 seconds, and is probably one of the most effective ways of preventing the spread of various infections/diseases.

[ams6110]

It is possible but also keep in mind that they are for the most part working in horribly primitive, unsanitary conditions, lacking supplies and basic utilities.

[danieltillett]

That is the description of the whole health infrastructure of west Africa before this outbreak.

[danieltillett]

The real fear is the sheer number of people getting infected. With a virus like Ebola every person infected increases the chance that Ebola will become human adapted. When you have a zoonotic virus like this spreading out of control imagine what might happen if it becomes adapted for efficient human to human transmission.