Vanity - Ebola model projects future case based on Daily Transmission Rate

My User Name on Free Republic is Scouter. I have been a member of Free Republic for 14 years. I don't write many vanity posts, but I consider this one to be very important. I had been working on this post for several days, and I was planning to post it tomorrow. But the Drudge Report headline CDC: PREPARE FOR EBOLA has moved up my timeline.

I have developed a model for making future projections of the number of Ebola cases. I have undertaken this project for several reasons. First, out of simple professional curiosity. Second, I believe the time has come to be concerned and to prepare for the possibility that the Ebola epidemic could spread to other countries, including the United States. And third, my daughter will soon begin working as a nurse in a major Pediatric Intensive Care Unit, which will likely see some of the first Ebola cases in the United States, should it make an appearance here.

I am not an epidemiologist, and I have no inside knowledge about the current Ebola epidemic. But I have spent the last 26 years of my career applying computers to the practice of medicine and to medical data. I hold a Master's Degree in Medical Informatics from a major university known for their expertise in that field. I currently work in that field at a large, famous, metropolitan teaching hospital. I am remaining anonymous only because I don't want my employer to be held responsible for this post in any way. It is my work exclusively, and I am responsible for any information or projections it makes.

The numbers produced by this model are "projections", not "predictions". That is to say, I do not predict that there will be x number of Ebola cases on any given future date. Rather, I "project" into the future, assuming a constant Daily Transmission Rate (DTR), based on past data. Any number of factors can influence future DTR, in either a positive (bad) direction, or in a negative (good) direction. There is no way to know how these factors will actually play out. If there were, then we would be able to make actual preditions. As it is, we are left only with the ability to say "If Ebola continues to spread at the same rate it has been spreading for the past x number of days (or months), then this is approximately how many people who will have contracted the disease as of this particular date in the future." Not ideal, for sure, but still quite useful to understand the seriousness of the situation.

I have validated the model based on actual data by calculating the DTR for various periods of time and comparing the model's projections with what actually happened in subsequent periods. This is the same concept that is being used by epidemiologists at CDC and elsewhere. It is a valid method, within the constraints I have mentioned above. My model has been completely in line with projections I have seen quoted in the mainstream news. It works quite well. If anything, my model's projections are a bit more conservative than some projections you may have seen in the mainstream media. I just take them out further than you have seen in other places.

That being said, the following projections are based on the Daily Transmission Rate (DTR) from June 1 through September 10, the last date for which I have data. The DTR has remained relatively stable over that period. To be conservative I assumed that the reported number of cases represent the true size of the epidemic. However, the WHO, CDC, Medicins Sans Frontieres, and Samaritan's Purse all agree that the number of reported cases represents only 25% to 50% of the true number of cases. I have decided to be conservative in the numbers published below, but the model allows you to adjust this percentage.

As you review these projections, remember to pray for all those who are currently affected by this terrible disease, those who have it, those who will die, and their families. Do not forget that these are real people with eternal souls, who will either go to heaven or to hell, depending on whether or not they die in friendship with God. Pray, too, for an end to this epidemic. Do not underestimate the power of prayer!

The following projections assume that the currently reported cases represent 100% of the true epidemic size. In other words, that there are no cases that were missed by the epidemiologists. We know this not to be true, so we know that the "best case" is something worse than this, assuming the Daily Transmission Rate remains stable.

Scouter Ebola Projection Model Version 1.0 - Ebola Case Projections

*********************************************************
Projection Parameters
*********************************************************
Start Date: 6/1/2014
End Date: 9/10/2014
Reported cases represent 100% of the true epidemic size
Daily Transmission Rate (DTR): 1.00422415489918
*********************************************************

Weekly for the Next 8 Weeks

Date        Cases                 Deaths                Daily New Cases       Daily New Deaths
==========  ====================  ====================  ====================  ====================
09/10/2014                 4,845                 2,376                   171                    84
09/17/2014                 6,227                 3,054                   219                   108
09/24/2014                 8,003                 3,925                   282                   138
10/01/2014                10,285                 5,044                   362                   178
10/08/2014                13,218                 6,482                   465                   228
10/15/2014                16,988                 8,331                   598                   293
10/22/2014                21,833                10,707                   769                   377
10/29/2014                28,060                13,761                   988                   485

End of Month for the Next Year from the End Date

Date        Cases                 Deaths                Daily New Cases       Daily New Deaths
==========  ====================  ====================  ====================  ====================
09/30/2014                 9,923                 4,866                   349                   171
10/31/2014                30,146                14,783                 1,061                   521
11/30/2014                88,357                43,331                 3,111                 1,526
12/31/2014               268,427               131,637                 9,451                 4,635
01/31/2015               815,475               399,911                28,713                14,081
02/28/2015             2,224,815             1,091,055                78,336                38,416
03/31/2015             6,758,941             3,314,601               237,983               116,707
04/30/2015            19,810,535             9,715,135               697,531               342,071
05/31/2015            60,183,993            29,514,379             2,119,084             1,039,204
06/30/2015           176,399,989            86,506,991             6,211,061             3,045,920
07/31/2015           535,899,508           262,806,446            18,869,075             9,253,441
08/31/2015         1,628,051,594           798,400,534            57,323,860            28,111,763
09/10/2015         2,329,918,242         1,142,597,677            82,036,655            40,230,979

The following projections assume that the currently reported cases represent 75% of the true epidemic size. Remember that Medicins Sans Frontieres, Samaritan's Purse, the CDC, and WHO all agree that the number of reported cases already vastly underestimates the true size of the epidemic. They say by a factor of 2 to 4.

Scouter Ebola Projection Model Version 1.0 - Ebola Case Projections

*********************************************************
Projection Parameters
*********************************************************
Start Date: 6/1/2014
End Date: 9/10/2014
Reported cases represent 75% of the true epidemic size
Daily Transmission Rate (DTR): 1.00422415489918
*********************************************************

Weekly for the Next 8 Weeks

Date        Cases                 Deaths                Daily New Cases       Daily New Deaths
==========  ====================  ====================  ====================  ====================
09/10/2014                 6,460                 2,376                   235                   115
09/17/2014                 8,373                 4,106                   305                   149
09/24/2014                10,853                 5,322                   395                   194
10/01/2014                14,068                 6,899                   512                   251
10/08/2014                18,234                 8,942                   663                   325
10/15/2014                23,635                11,591                   860                   422
10/22/2014                30,635                15,024                 1,115                   547
10/29/2014                39,709                19,473                 1,445                   708

End of Month for the Next Year from the End Date

Date        Cases                 Deaths                Daily New Cases       Daily New Deaths
==========  ====================  ====================  ====================  ====================
09/30/2014                13,556                 6,648                   493                   242
10/31/2014                42,764                20,972                 1,556                   763
11/30/2014               129,996                63,750                 4,729                 2,319
12/31/2014               410,085               201,107                14,920                 7,317
01/31/2015             1,293,657               634,413                47,066                23,081
02/28/2015             3,651,570             1,790,739               132,851                65,150
03/31/2015            11,519,271             5,649,079               419,092               205,524
04/30/2015            35,016,714            17,172,283             1,273,972               624,759
05/31/2015           110,464,001            54,171,820             4,018,881             1,970,869
06/30/2015           335,792,614           164,673,529            12,216,744             5,991,122
07/31/2015         1,059,294,023           519,480,413            38,539,038            18,899,640
08/31/2015         3,341,657,268         1,638,757,001           121,575,553            59,620,953
09/10/2015         4,840,743,028         2,373,912,370           176,115,013            86,367,239

Obviously, there are many factors that will affect these projections. Rather, this model simply projects the number of cases and fatalities based on the current Daily Transmission Rate (DTR), which has been stable for about 3 months. Consider the following other factors that are likely to change the DTR (either for good or for bad) as we move forward from today:

While the numbers quoted above are grim, they do not yet represent fact. Do not panic, but do not be complacent, either. Any preparations you make to "shelter in place" will serve you well for other contingencies, too.

On the other hand, epidemiologists are already saying that the number of cases is already doubling every two weeks. That means that the numbers I've posted above are actually quite conservative.

This model is contained within a macro-enabled Microsoft Excel 2010 spreadsheet (i.e., a .xlsm file). I would be willing to share it with other Freepers if someone can provide a place to post it for download and can tell me how to sanitize my name from it (again, I don't want my employer to be in any way held accountable for this).

I’m not sure when you go out beyond 3 months that it’s still a valid model.

I do see a similar flex point in the graphs of other models at that same point. I agree that any error in my model will become greater as the model projects further into the future. But that's going to be a limitation of most models, I think.

Try this. Try to express it as a simple day to day formula formula without exponents. Day1 = Day0*whatever+/-whatelse. If you can do that, we can test to see if the exponent formula is correct.

I'm kind of a literal person... what do you mean by "whatever+/-whatelse"? My exponent?

Basically what I was asking is what does the formula look like if DaysOut is 1.

Cases ^ (((DTR-1) * DaysOut) + 1).
Cases^(((DTR-1)* 1)+1)
Cases^((DTR-1)+1)
Cases^DTR

I was hoping to get rid of the exponent completely, but an exponent is inherent to your formula.

So Day1 = Day0Cases^1.004.

If Day0 = 100 then Day1 = 1.018
Day2 = 103.8
Day3 = 105.7

I'll add another problem, based on my observations over a 6 year period with each year including several months in the hospital with relatives.

Our hospitals may have good written procedures to stop contagious and infectious diseases, but the staff routinely breaks protocol. Not just during flu outbreaks, but also dealing with things like VRE where strict isolation protocol is supposed to be followed.

A recent article here quoted the CDC as saying that any hospital could isolate an Ebola patient in a regular private hospital room. However, if you saw the area where Dr. Brantly was treated, that's not what they had.

First off the regular private rooms do not have negative air pressure, but Brantly’s room did. Also, Brantly’s room had an entry way room/area and his doorway had red tape outlining a rectangle in front of it.

The area outside the doorway and inside the tape was also considered part of the hot zone. Most of the private rooms as well as ICU rooms did not have that double entry. The team caring for him had the full PPE which is more than the usual isolation garb.

Even in the ICU which had negative air pressure, there was much less than what they used with Brantly. If all we have is a few cases that can be contained at places such as where he was, then the USA is likely able to handle it.

Let it get out of hand where regular hospitals are also needed to treat cases, I am sorry to say, that I am a skeptic.

My brother-in-law recently died from a short battle with cancer at home. While he was dying he was kissed and hugged repeatedly by his wife, kids and grandkids. They knew he was dying and they were saying goodbye.
People aren't robots. When someone is dying at home of Ebola they're not going to gown up. They're not going to refrain from kissing and hugging them out of love and compassion. That's exactly what's happening there. That's part of the "culture" that we have over here.

First of all, cancer is not contagious--I have never heard that even cancers caused by viruses are contagious. Thus, there is a world of difference between hugging and kissing a dying cancer patient and someone dying of Ebola. I can't imagine too many people would want to physically comfort someone who is covered with vomit and feces--they'd be rushing that person to the hospital. And then that person would be isolated.

Not only do we take infection control seriously, we do not have the other customs that Africans have. We do not bathe the bodies of loved ones with our bare hands. We do not give corpses enemas with our bare hands. We do not stroke corpses during the funerals. Many people in Africa have acquired Ebola during funerals through these practices.

I read it. I must say, that more than one article I’ve read over the last month has quoted virologists who have worked in Level 4 labs, or those who have treated patients to acknowledge that Ebola sdares the crap out of them.

Yet we have this group of people who claim that it could not possibly ever get out of hand here.

They may be right, but I’d feel better if they were worried, and explained to all of us dummies what we should do to prepare, if a worst case scenario breaks out even if they think such is not possible.

The point was that a dying loved one IS going to be hugged and kissed by loved ones. It's saying goodbye. And they're going to be cleaned up by those same loved ones. They're not going to know it's Ebola until it's too late.

The point is that we do not do that when a loved one has a contagious disease. We've had too many pandemics in our past and we understand how disease is spread. My ancestors survived several pandemics that decimated the population of Europe, as well as the 1918 pandemic that is still a source of fear and horror.

Would you, personally, hug, hold, and kiss your loved one that you know is dying from a deadly contagious disease like Ebola? If the answer is no, then why would you assume that anyone else raised as an American, and steeped in American culture, would do that?

Would you, personally, hug, hold, and kiss your loved one that you know is dying from a deadly contagious disease like Ebola? If the answer is no, then why would you assume that anyone else raised as an American, and steeped in American culture, would do that?

The point is that there are hundreds of thousands of low information people out there. When a loved one comes down with what looks like the flu do you seriously believe that nobody in the family is going to touch that person? That they're going to wear a hazmat suit whenever they're around them? They're not going to touch the soiled bedsheets and clothes? Seriously?

Rich21IE:" That’s just appalling.
This country has been damned by the liberals and their immigration programs."

It's worse than that !!
Why are we so insistant about soverignty of Ukraine lands
Why are we so insistant about soverignty of Gaza
and yet our pres__dent leaves our Southern Border wide open and is in keeping with the U.N. policy of migrants and immigrants
and denies our own soverignty and borders ??

And that level of thinking applies to all levels of people. Substitute “lose my job” to “seal that $2 million deal”.

“Honey - she only has the flu. If we take her to the hospital they’ll want to quarantine the house until they get the tests back. If I don’t make it to work for three days I’m going to lose my job, and we’ve got bills to pay. Let’s just see if it runs it’s course.” And that level of thinking applies to all levels of people. Substitute “lose my job” to “seal that $2 million deal”.

Good points. The press is minimizing the Africa thing by calling these types of things "cultural" but we have the exact same cultural challenges just on a different level.

I have had relatives with suppressed immune systems.

You hold their hand. With a glove on. With a mask on.

You make sure that you do not bring any ‘bugs’, ‘germs’ into the room.

Its that in reverse.

The particular details you put into this projection don't really matter, and it doesn't take any particular training. If you make any projection based on a simple growth rate like this it is eventually going to show the whole world consumed. This isn't meaningful. They will all end the same way. Change the DTR and it shows the whole world dead a week earlier. So what?

This isn't how real outbreaks progress. Things will change over time. Your DTR won't be constant. A real projection would have to model transmission rates as the disease moves into new territories and populations. But of course we won't really know how that's going to work until it happens.

Over 2 billion people may be dead within a year.

Ebola model projects future case based on Daily Transmission Rate

"Check out article for following projections based on the Daily Transmission Rate (DTR) from June 1 through September 10, the last date for which I have data. The DTR has remained relatively stable over that period.

"To be conservative I assumed that the reported number of cases represent the true size of the epidemic. However, the WHO, CDC, Medicins Sans Frontieres, and Samaritan's Purse all agree that the number of reported cases represents only 25% to 50% of the true number of cases. I have decided to be conservative in the numbers published below, but the model allows you to adjust this percentage."

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