Science is typically never complete nor fully certain. Science is more of a process, than a destination, particularly when it comes to incredibly complex biological organisms. There's almost something new to learn.

I posted that link to that WHO report in the original Ebola thread and it seems pretty clear that the intent of that passage is to say that there was someone with a confirmed case (although they don't define whether it was laboratory confirmed or just clinically confirmed) with an incubation period greater than 21 days. Also the way they broke down the percentages as 95 and 98%, it seems like it could be a probabilistic breakdown rather than an actual count, which means the 21-42 day group may not have literally been 3 out of 100 cases. Based on a probabilistic distribution, a single extreme outlier could span that 95-98% group (and the other couple percent left over are just missing data).

That said, I have not been able to find any clarifications or verification about that WHO report since I first posted that link, so I'm unsure how much confidence to put into that statement that there were some people with incubation periods beyond 21 days. Just as there is tremendous undercounting going on, I'm sure there are plenty of cases where just the wrong information is recorded, and that could easily turn out to be the explanation once the smoke clears.

But back to a point I just made above--our experience with Ebola in the First World has turned out much differently than most people--including myself--feared, based on what it does in African populations. The track record so far indicates a disease which is serious but which the human immune system can beat even without any proven treatments, and indicates a virus which does not rampage through the populace like the Norovirus on a cruise ship.

Regarding quarantines/isolation policies, the fact is that these policies are a combination of science and other political factors, so it is not surprising that different people in charge (like Gov Cuomo or Christie) come up with different policies. Now that some states have implemented their own quarantine policies, there is a big push to harmonize them but of course there is pushback on many sides. If policy were based solely on good science, in my opinion, we would probably follow something like the MSF guidelines that Dr Spencer was following in NYC when he became symptomatic. Policies based more on theoretical risks and trying to appease the public end up looking like New Jersey's original policy of mandatory 21 day quarantine, no matter what.

Arney,

I think you hit some key aspects of the statistics. One further point regarding your comment ".....and it seems pretty clear that the intent of that passage is to say that there was someone with a confirmed case (although they don't define whether it was laboratory confirmed or just clinically confirmed) with an incubation period greater than 21 days....."

Keep in mind that until very recently, all the human data was from W Aftrica, and much of it during a raging epidemic. Since this is a situation where one cannot set up a controlled experiment, all the data that went into those statistics was by nature somewhat anecdotal. The folks compiling the data had to assume that the person became infected during their last known contact with an active ebola case. It is entirely possible that some of those outliers ( > 21 day incubation) actually became infected later, and hence their incubation period was actually within the 21 day period. Remember that infection is rampant in the area, and overall levels of sanitation may not be as good as they could be. It is possible they came into contact with the virus from some other source, either a sick person or some contaminated item, without realizing it. The greater than 21 day incubation data points may in fact be just be inacurate data points.

EDIT: One further bit of info. The New England Journal of Medicine (a very highly respected journal) just came out with an editorial on ebola and quarantines. One quote struck me as summing things up nicely:

Bottom line, we don't know what we don't know, and science is not perfect. A little caution should be tolerated and not be a political weapon. Implementation of policies by poorly trained people is always rough and difficult, but we should err on the side of caution.

Too much of the current policies recommended relies on individual cooperation and honesty. My experience with human beings is that many are not honest and will take a narcissistic attitude to take care of their own desires.

We can take caution and protect civil rights at the same time, they are not mutually exclusive.

This article says that the Joint Chiefs Chairman's suggestion to monitor soldiers for 21 days in Italy is because it is simpler and more efficient to just uniformly order all of them to keep separate from other service members and the public for 3 weeks than it would be to assess each person's risk on a case-by-case basis and to actively monitor the higher risk ones.

Ummm, OK. I guess that makes sense. Just order everyone to stay out of sight and be sure. It's the same thing when trying to import your dog into many countries.

Arney and AKSAR; thanks, that clarifies a lot about the sequence of the disease, especially the editorial from The New England Journal of Medicine.

So my remaining concern is compliance and for want of a better term the "honesty" of the self reporting:


This pretty much sums up where I am at now. I've had the same experiences with humans as Montanero. Besides simple honesty, there is the psychological problem of "denial" when they first get a temperature rise or begin to feel ill.

As someone else pointed out, the quote from Dr. House applies "Everyone lies."

Quite true, which is why quarantine policies tend to be a mix of science and other factors. Was disappointed to read in this article (if true) that Dr Spencer in NYC "lied" about being self-quarantined at home instead of riding the subway, going bowling, etc. (I'd like to hear his side of the story, though, since this is the NY Post reporting)

According to the MSF protocol he was following, it was permissible for him to be out and about before he became symptomatic because he would not be contagious, so it wasn't purely a medical reason for not being honest up front about his movements, if he indeed tried to cover that up. Perhaps the backlash against Dr Nancy Snyderman weighed on his mind.

I read that the folks in Maine are freaking out about nurse Hickox returning there even though she's without any symptoms and already tested negative twice. I still need to read up on the legal aspects of her situation with the Maine authorities. Only scanned some headlines earlier.

According to an article in the NY Times, people who even work in the same hospital where an ebola patient is being treated are now being stigmatized, even if they are not in any way connected with treating the patient.
Closer to home for me, a school district has had dispel ebola fears when a teacher returned from a vacation to South Africa, 3,000 miles from the area of the epidemic.

Unfortunately, the "better safe than sorry" approach is subject to the Law of Unintended Consequences. Quarantining people without good, solid, medically supported reasons only serves to increase the general paranoia about ebola. The unintended consequence is that if people think they are going to be stigmatized just for working in the same huge hospital as an ebola patient, or for traveing anywhere on the continent of Africa (no matter how far from the epidemic), then this just increases the incentive to be less than truthfull about where you have been, what you have done, and who you have been near. Thus your "....experience with human beings is that many are not honest and will take a narcissistic attitude to take care of their own desires" becomes a self fullfilling prophecy.

More (public) information from the CDC via a poster, on how Ebola is spread, highlighting the "airborne" vs "droplet" spread (a sneeze which can spread Ebola is via droplet, not airborne).

IMO, this, while true, is not helpful in reassuring the public; it can appear that the CDC is "lawyering" words. I suspect that the difference between "airborne" and "sneeze" will be lost on most folks; the effect might be to further erode CDC credibility and induce fear.

Here is the poster they have released:

http://yournewswire.com/wp-content/uploads/2014/10/Screen-Shot-2014-10-28-at-2.05.53-PM.png

That editorial is excellent. I thought they started to become contagious as soon as they started showing a fever, but this clearly refutes that.

Also, the comments about Duncan's family and the caregivers it was passed to also help shed some light how this propagates and when the most risk of contraction comes into the picture.

That's an excellent article, very balanced. It's important to note the government's obligation to use the method least restrictive of civil rights in order to achieve the goals. That means testing, not quarantine (unless someone refused testing).

I see that the nurse in Maine won her lawsuit. News reports suggest to me that the judge struck a very good balance.


I have seen a of summary of exactly one survey on this outbreak, covering all of 44 cases, which saw an incubation period of between 6 and 12 days. Not much to go on for this outbreak. That survey may have discarded statistical outliers as bad samples.


There are no techniques with 0% false negatives: if nothing else, you're going to have mislabeled sample vials from time to time. Never forget "a chain is no stronger than its weakest link" whenever someone has to scribble a name or ID on a specimen label.

One question with PCR is how many iterations / amplification to use. More is more sensitive but more expensive and subject to more false positives. If the virus is there but was missed, they didn't amplify it enough.

And there's always the question of whether FDA approval is granted yet. This is where PHRASECENSOREDPOSTERSHOULDKNOWBETTER.'s czar could be really helpful: walking paperwork through the FDA process.

(since when has using the President's unembellished name been censored here?)

(I think it take about four hours from when the sample is put in the machine to a result; it may be faster now)