Tag Archives: Ebola 2014 outbreak

#Ebola in West Africa: Update

WHO has put out very few updates in the last several days. The most current update is August 28th, and it pertains to information from August 26th and before. Based on that update, the total number of cases (confirmed, suspected, etc.) is ow 3069 with 1552 deaths. The number of new cases per day may be increasing, may be decreasing; hard to say at this point. Here’s the new cases per day since the second week of July:

Screen Shot 2014-09-02 at 11.08.33 AM

Senegal now has one case, a person who traveled there from Guinea. He had contact with a lot of people including health workers and family before it was figured he may have Ebola. There is no word from the Congo since I last wrote about it, at least from WHO.

I’m sure Murphy’s Law will apply and WHO will issue new information soon after this post goes up, so expect an update very soon.

#Ebola: Second, possibly third outbreak, West African outbreak growing

The number of people known or suspected to be infected with Ebola in the West African outbreak is increasing, and the rate at which it is increasing is increasing. About 40 new cases are being reported per day on average, but the number of new cases has been going up by a few a day.

However, it is still unclear that these numbers represent what is actually happening on the ground. There is little confidence that the WHO has a good idea of who is currently stricken with the disease, and efforts to contain those who are have had mixed results.

A second outbreak is now occurring in the DR Congo (formerly Zaire). This is a second separate outbreak. So, it is NOT correct to say that Ebola has spread into the Congo. It didn’t. It emerged there independently.

What are the chances of that happening? I have long maintained that the conditions for Ebola spreading into human populations include factors that make the overall chance of that happening, for a large region, go up enough for multiple simultaneous epidemics to be more likely than chance might suggest. Perhaps I’ll discuss my reasoning for that another time. In any event, the DR Congo outbreak, about which we know very little so far, appears to be a different strain of Ebola, so this is not the Wester African Ebola spreading to Central Africa.

There are reports of a third outbreak of an unknown disease that might be Ebola also in the DR Congo. But that could be a lot of things. Including Ebola… so we shall see.

Also, there is one new case in Nigeria, after a period of several days with no new cases.

There is a cure for Ebola, we have it, we just don't let anyone use it.

LATEST UPDATE HERE … new numbers just in from WHO, and they are bad.

I had suspected this might be the case. Disease like Ebola are potentially easily cured using serum. Here’s the idea. Someone gets the disease and survives, and their body now produces products that give them an immunity. So, you take a bunch of their blood, clean it up as best you can, and inject the serum (the cleaned up blood, to oversimplify) with these immune products, in to a person with the disease. That stops the disease, at least some of the time. The early history of the discovery of many nasty viruses involves several stories like this, where a researcher or physician is infected, seemingly likely to die, and is given a serum and lives.

The serum treatment is potentially very dangerous because it can include who knows what from the other person’s blood. But it is quite reasonable to suggest that we can make a product that is based on serum that is clean and effective. In this case, specific products were obtained from infected mice.

And, apparently, there is such a thing, it is a secret, and it is reserved only for select individuals (because there probably isn’t much). Oh, and it is totally experimental and until now, never before tried on humans. From CNN:

Three top secret, experimental vials stored at subzero temperatures were flown into Liberia last week in a last-ditch effort to save two American missionary workers who had contracted Ebola, according to a source familiar with details of the treatment.

A representative from the National Institutes of Health contacted Samaritan’s Purse in Liberia and offered the experimental treatment, known as ZMapp, for the two patients, according to the source.

According to company documents, four monkeys infected with Ebola survived after being given the therapy within 24 hours after infection. Two of four additional monkeys that started therapy within 48 hours after infection also survived. One monkey that was not treated died within five days of exposure to the virus.

…In the monkeys, the experimental serum had been given within 48 hours of infection. Brantly didn’t receive it until he’d been sick for nine days.

The medicine is a three-mouse monoclonal antibody, meaning that mice were exposed to fragments of the Ebola virus and then the antibodies generated within the mice’s blood were harvested to create the medicine. It works by preventing the virus from entering and infecting new cells.

Brantly asked that Writebol be given the first dose because he was younger and he thought he had a better chance of fighting it, and she agreed. However, as the first vial was still thawing, Brantley’s condition took a sudden turn for the worse.

Brantly began to deteriorate and developed labored breathing. He told his doctors, “I am going to die,” according to a source with firsthand knowledge of the situation.

Knowing his dose was still frozen, Brantly asked if he could have Writebol’s now-thawed medication. It was brought to his room and administered through an IV. Within an hour of receiving the medication, Brantly’s condition was nearly reversed. His breathing improved; the rash over his trunk faded away. …

Writebol also received a vial of the medication. Her response was not as remarkable, according to sources familiar with the treatment. However, doctors on Sunday administered Writebol a second dose of the medication, which resulted in significant improvement.

This is an untested drug that is not available for general use. This has led to some argument of whether or not it can be called a “treatment” or a “cure” because it has not yet gone though the process of development, testing, and deployment. One could call it a “potential cure.” The key point, is, that it could be developed and implemented, and since the science of making an antibody basted treatment is well established, it is hard to understand why this has not happened. yet. I suggest that all it would take is deciding to spend the money and effort on developing it, rather than simply ignoring Ebola because it is not Malaria.

If I was President Obama, I’d simply order the military to take this to the next step. The US Army has done as much research on Ebola as any other agency. It would be a simple matter to move a few budget items around and allow USAMRIID organize, using its own people and consultants, to move forward (because you know the present Congress is never going to authorize spending money on helping sick people in Africa, even though this is also very much about the United States.

It is the right thing to do.

Ebola Perspective: Risks of spread to the US and elsewhere

LATEST UPDATE HERE

It is true that this particular outbreak of Ebola has taken health officials somewhat by surprise. It is impossible to know, but I suspect that if you had asked a few ebola experts, a year ago, if there could be an epidemic that would spread across three or four countries, infect a couple thousand people, and last with no sign of letting up for a few months (that is the current situation, more or less), most would say no, probably not, though it is within the range of possibilities. Does the fact (assuming it is true) that this particular Ebola outbreak is unprecedented and kinda over the top even for an over the top disease like Ebola mean that there is something different about this Ebola or this outbreak? That is a question that may be on your mind.

Another concern is the possibility that since this outbreak involves populations with more mobility including via aircraft than previous outbreaks that the Hollywood Scary Fiction scenario could happen. Here’s how that goes. Someone infected with Ebola, but not symptomatic, gets on a long plane flight, maybe with a few legs and layovers. They start to get sick on the first flight, and after changing planes twice and being very sick for the last leg, they get off the plane and collapse, are taken to a local hospital very far form the Ebola epidemic where no one is expecting Ebola, spend a little quality time in the waiting room, and are finally put in an in-patient unit in a room with two or three other people. Hundreds of people have been near this person. The patient threw up in the bathroom of each of the airplanes he was on, and later someone filled the sink in the same bathroom and used the water in the basin to wash his or her face. He drooled on his pillow while sleeping in his seat, and somehow the person next to him ended up with that pillow and slept on it for an hour. He threw up on some nurses and some orderlies had to clean up his diarrhea in the hospital a few times. And so on. By the end of all of this, a half dozen people are infected with Ebola, including a personal trainer, a grade school teacher, and four nurses. That’s just the first scene in the movie, long before the character played by Morgan Freeman is on the scene, and when the character played by Morgan Freeman shows up, you know things are getting serious.

A variant of that concern is this: Two aid workers helping with the Ebola epidemic, Americans, catch Ebola and are very ill. It is decided to fly them back to the United States for treatment. This brings Ebola into the US, where it could spread to other people because, well, because Ebola! But is this a realistic concern or just a Hollywood studio’s wet dream?

At this point in the epidemic we are seeing the usual bifurcation of reaction among the general public, sciency bloggers, and the press. On one had there is growing panic, people either being very scared, for real, or people or press outlets shopping fear on the market because it sells. On the other hand there is the stern corrective statement that all your fears are invalid, Ebola isn’t going to get out of hand, isn’t going to get to the US, there is nothing to worry about.

At the same time there is a parallel and equally bifurcated rhetoric about the bigger picture, about dealing with Ebola as a public health problem. On one hand you have people asking for a vaccine, or some sort of cure, to address this thus far orphaned disease, because they are worried about it. On the other hand you have people noting that Malaria kills millions a year, and most years, Ebola kills no one, and when there is an outbreak, it only kills dozens or hundreds, except this last time which is still only many hundreds dead and the very low three figures sickened.

Every one of the above mentioned concerns is valid and invalid at the same time, and every one of the reactions to the current Ebola crisis is both correct and incorrect at the same time. Let me explain.

What is the meaning of the bigness and badness of the Ebola 2014 outbreak?

There may be new things to learn about Ebola from this outbreak, but that won’t be until after the dust has settled and scientists have had a chance to look more closely at the data, and the virus, and everything else. But there does not seem to be anything new or unusual about the disease, and I don’t think there is any major difference in how the outbreak is being handled. But there are two differences from earlier outbreaks, one of which is certainly relevant to the large size of this event, the other perhaps important but as yet unclear.

<li>Most, really all, prior outbreaks occurred in areas where the affected population was relatively thinly scattered on the landscape and the movement of people in and out of the area was minimal and slow. This outbreak is happening where there are much larger concentrations of population and a lot of movement of people.  This has simply upped the chance of transmission in close quarters (higher density) and made for opportunities for spread to previously unaffected settlements.</li>


<li>There has been resistance to health workers coming into some villages.  This story is spreading around as though it was a major thing, that large areas were becoming dangerous or difficult for health workers to enter or work in.  We need to be cautious in drawing conclusions from the news.  It is very easy for westerners to slip into blaming the natives for their own difficulties and contrasting native ignorance with Great White Smartness.  There may well be areas where this is happening or important but until there is some actual unbiased carefully collected and evaluated information on this, please don't draw conclusions.  If you hear about something that looks like a great story, there is a good chance that it is a great story.  Emphasis on "story." </li>

This particular Ebola outbreak is really like all the others, but jumbo size.

Could sick aid workers being brought to the US spread the disease here?

No.

You can stand in a room with a person infected with Ebola ten feet across the room from you, and stand there for hours, without a mask, and you will not, can not, get Ebola. It simply isn’t transferred that way. Clean up Ebola vomit, Ebola diarrhea, physically move Ebola victims from bed to bed, give them a sponge bath, tend wounds or other injuries, insert and remove IV’s, handle the bodies of recently deceased Ebola victims, and especially, give traditional treatment to those bodies which, as is done in many cultures, which may involve cleaning and even internal cleaning or handling of organs, etc. etc., and you’ve got a reasonable chance of getting Ebola. Even then, the number of health care workers who actually get Ebola is probably very small. Tragic and horrible when it happens, but a few out of thousands most directly exposed and at risk for months is a small number.

The people who are being transported to the US are isolated, in negative pressure facilities, and are being handled with kid gloves. Well, latex gloves, actually. They can not infect anybody but their immediate caretakers, and those individuals are very well protected.

There is a risk of a different sort, though. While these particular patients are being handled with great care, there are healthy helpers, medical workers or others, who have been working with Ebola patients and seem to have not contracted the disease, who are occasionally wandering off to their respective homes and, I’m pretty sure, not being quarantined. I am not sure if all the people involved in helping in West Africa are being tested or properly watched. They may be, but there is some evidence that this is not the case. I’d like to learn more about that, and I hope we don’t learn anything the hard way.

One US based doctor has returned to the United States and decided to quarantine himself. Alan Jamison will keep himself separate from society for 21 days since his last potential exposure to Ebola.

If he is doing this on his own, there is the implication that doctors or others who were working with Ebola victims are being allowed two wander off and commune with the rest of us with the prospect that they are infected and eventually could spread the disease. However, I’m not sure that this is true. I don’t know that Dr. Jamison was not tested, I don’t know how much exposure he had and I don’t know what the procedure is for managing this potential problem. This is one guy who may be making hay where there is no grass. Worst case scenario, though, is that a health worker gets sick, the beginnings of Ebola like symptoms emerge, and the health worker gets treated. Nobody who has been working with Ebola patient is going to get a head ache, feel like throwing up, and say to themselves, “Hmm. I wonder if I’ve got allergies or something?”

We should be worried about people wandering off, leaving the sites of the outbreak, generally. That’s clearly how this has spread to begin with. This applies to health workers and regular people. It applies to journalists in the field. We should not assume, but we can reasonably hope, that people are doing the right thing. But even when they don’t, remember, this is not measles, which is highly contagious.

(Also, in case you didn’t know, Ebola is of course already in the United States. See this.)

Can the scary hollywood scenario happen?

Yes, of course it can. There is nothing in that scenario, taken on its own, that can’t happen. Bodily fluids get around. People are confined on aircraft, share a bathroom, and occasionally eat each other’s cookies by mistake. I don’t think there is any scientifically valid way to suggest that people who are symptomatic with Ebola are anything but a nightmare on a regular airplane flight, hanging around in airports, sharing cabs, et. When I hear international health experts saying that the chance of Ebola transmission on an airplane is pretty much non existent, I want to ask them: Ok, so, you’ll be entering and leaving the sick rooms of Ebola patients, maybe taking your kids along because it’s Follow Your Parents to Work Day, and maybe even have your kid sit next to the patient in bed and read them a story, without any protective gear at all. Right? No, absurd.

However, the crazy scenario I gave you above, with the vomit and the pillow and the bathroom, requires a lot of things to go wrong in sequence, which is pretty unlikely. Also, the worst case scenario is that a few people end up with Ebola. It would be very hard for that to spread in the US. We’re too good on our health care, even when it seems we are not. On the other hand, if an air route with a symptomatic Ebola patient is sending people to any of many other places, with high population density, little education or information about things like Ebola (or even a belief that it is not a disease you get from other people) and no monitoring, I’d worry that smaller outbreaks could show up in other countries or other cities, in West Africa, elsewhere in Africa, or beyond. You can say that chances are it won’t happen. But it did happen. Ebola is in multiple countries spreading from multiple sites in West Africa.

I’m pretty sure the people who deal with Ebola, though, try to not take chances. Rhetoric to the contrary is to avoid panic. Avoiding panic is good, and in fact, panic is unnecessary. Ebola is not that contagious. But somewhere between being concerned and avoiding panic by making it sound like Ebola refuses to pass from person to person on air planes, there is clearly something lost in translation.

Who cares about Ebola, it is not Malaria!

To me this is one of the most insidious problems we have and it doesn’t just apply to Ebola vs. Malaria. Let me give you an example from an entirely different area.

How much money have spent on the science of subatomic physics, say, just in the US. And, what are the benefits? More importantly, what were the benefits that were specified at the outset of various research projects, and which of those have been realized?

The answer to that second question is probably zero, zero. No benefits were specified, and thus, any gained don’t count. You are probably thinking, “No, wait, what about the knowledge, and all that stuff!?? That was surely specified in the grant proposals!” No doubt, but simply advancing knowledge is not a benefit. How do I know that? Malaria! Those physicists may have advanced our knowledge, and as a side effect invented the DVD and stuff, but nobody cured Malaria. Therefore it doesn’t count.

Sounds like an incredibly stupid argument, doesn’t it?

Now, side step over to Ebola. Is creating, say, a vaccine to address Ebola worth it? No! Why? Because Malaria! Malaria is way bigger, kills more people, is a truly serious public health problem, Ebola is rare. So if you’ve got some research money don’t spend it on Ebola, spend it on Malaria.

That would be the smart thing to do!

This is also an incredibly stupid argument, for a few reasons. The only reason you can compare Ebola and Malaria is because they are both diseases. They aren’t even the same kind of disease, they don’t have the same geographical spread (though it is overlapping). But they are diseases, so when we consider spending resources on research in one, it is natural to compare to the others. But they are also two different things. If I had a million dollars in the bank of my Malaria Vaccine Research Institute and gathered all the scientists together and said, “OK, folks, until we’ve spent this one million dollars, I want you all working on Ebola instead of Malaria, K?” they would look at me funny for a while and then call my wife to take me home. Ebola is a virus, Malaria is a cellular organism. They are very different things. The expertise and lab equipment would not be in my Institute. I might as well tell my scientists to spend a million dollars working on the next generation of high definition TV. That would be cool! And, suggesting that we compare the costs and benefits of that project to working on Malaria or Ebola would be dumb.

One of the benefits of working on a vaccine for ANY virus is advancing knowledge of vaccines for viral disease generally, and we have a lot of work to do on vaccines for viral diseases. Perhaps work on Ebola would have some great side benefits. Indeed, money spent on a vaccine for Ebola would very likely produce … wait for it … a vaccine! Money spent working on a vaccine for Malaria has thus far failed to produce squat.

A vaccine for Ebola is probably relatively easy to develop. Ebola is not a human disease. It comes from an animal reservoir. Ebola, if hit with a vaccine in human populations, can’t evolve resistance to that vaccine (or other treatment). Humans have little or no history of immune response to Ebola, and a very long (in essence, multi million year long) history of immune response to Malaria and its cousins. Developing an Ebola vaccine would be like putting up a childproof gate in your house, where the 2 year old is Ebola and the childproof gate is the Vaccine. Developing a vaccine for Malaria is like trying to stop a squadron of Navy Seals from penetrating a drive-in theater at a date and time of their choosing.

This is why literally billions of dollars has been spent … billions, seriously … on developing a Malaria vaccine and there isn’t one. I would venture to say that if we looked at the part of the money spent on Malaria research in general (including vaccines) that covered just couriers and postage over the years, we’d have enough to fund a full on Ebola vaccine development program. Maybe not. Maybe you’d have to add in a few percent of the money spent on conferences (which are very important, I’m not saying they are not) by Malaria scientists. There is probably more money being spent right now on retirement payments to retired scientists who spent most of their time working on Malaria than needed to build an Ebola Research Center that could get a vaccine out there in a few years. Seriously. Please don’t compare Malaria to Ebola and use that to suggest that we should ignore Ebola. The crumbs that fall off the pieces of Malaria cake at the Malaria birthday party would be enough to handle Ebola. (Bonfire of the Vanities Reference.)

But still, why should we bother with Ebola?

Why bother with any disease? Why not figure out which one disease causes the most mortality or morbidity, and disallow any research on anything else? Then, when that is solved, move on to the next one. There are several reasons to not do this. First, it might not be possible to solve the big bad disease quickly, or ever, so the entire research program would spin its wheels forever. Second, the second and third and way down to the tenth or twentieth diseases are all real disease people really get and that really cause suffering. While the argument that spending excessively on a rare disease is a poor choice, spending a modest amount on a very addressable problem that is also small is exactly what we should be doing. Third, you can and should think of some of this as pure research. Pure research is where scientists seek out the answers to questions in a special category of question: Questions that scientists ask. No other criteria need apply. Scientist tend to ask questions that are at the edge of knowledge, or perhaps that are hanging around this or that water hole of ignorance. Scientists ask the questions they ask because they have two characteristics: There is something unknown, and there is something about that unknown thing that is knowable. With research. Usually.

Now go back to Ebola again. Doesn’t somebody want to know about Ebola? Of course they do. Ebola is one of a family of viruses, the Filovirus family, that includes some pretty benign viruses and a handful of nasty ones (Ebola isn’t the only one). In the past there was a lot of research interest in the filovirus family for use as a biological weapon. Imagine making an Ebola like virus that spread though the air! You could really kick ass, militaristically speaking, with such a weapons. But, fortunately, we as a species have recently decided to not view biological weapons as legitimate. Research on biological weapons continued, of course, long after they were outlawed because we assumed we needed to “understand them” (make them and test them on rats) in case the other guys were making them, so we could deal with them. But I’m pretty sure most of that research has gone by the wayside as well. I would not be surprised, and I’m not much of a conspiracy theorist so I don’t want to emphasize this too much, if a lot of the work to make an Ebola vaccine was in a file drawer somewhere.

Also, there is the simple stark reality of Ebola. If you are a typical American you may not care about Ebola because it is in a different country and won’t get here and there are other problems. But say you are like my neighbor here in Coon Rapids, Minnesota, Decontee. Decontee is Liberian. She is part of a large Liberian community here in the Twin Cities. Many Liberians are American Citizens with strong ties to Liberia. There is constant travel back and forth. I asked a Liberian guy I know where he gets his sombe (a wonderful traditional West and Central African dish) and he said “From my grandmother.” “Does she grow it?” “Yes. In Liberia. I get it when I go there.” The point is, there is a lot of back and forth. To be an American who is Liberian is to be a member of a community of people who is currently, at this very moment, threatened with Ebola. People in your community, in your family, can get Ebola. Decontee’s husband and her sister in law both got Ebola and died of it last week. Ebola is a problem that affects communities that are Diaspora that include our very neighbors and friends. It should not be an orphan disease.

So wait, there was way too much nuance and possibly contradiction here, what am I supposed to think?

I don’t want to tell you what to think.

But in this case I’ll make a suggestion.

Do not be worried about the health workers being brought back to the US. Indeed, at this point, openly worrying about this can do little more than make you look a bit dumb and a bit insensitive.

Yes, worry about the possibility of Ebola getting “out” to pretty much anywhere, elsewhere in Africa, to the US, etc., because it can. But don’t worry too much. The chances are low. Forget about this “Oh, Ebola is not transmitted between people on airplanes” magical thinking. Of course it is. But Ebola is always hard to transmit, even on airplanes. In other words, be realistic.

Forget about this comparison between Ebola and Malaria. When the Malaria people turn up a vaccine after spending billions of dollars of research money we can make a comparison. At the moment, Ebola is probably a vaccine-ready disease, and Malaria is not. You are comparing apples and oranges. No, worse than that. They’re both fruit. You are trying to compare, in a cost benefit analysis, the efficacy of spending money on a new car vs. working out whether or not it is worth clipping coupons when you go to the grocery store. Why are you doing that?

But, if you are a member of a community like the various African communities in the US, then you do indeed have more of a concern. Not so much that travelers will bring Ebola to your doorstep, though that is a tiny bit more likely for you than for some others, maybe. But because your community is being directly affected because your community lives in two worlds, and one of those worlds is being invaded by a monster.

Ebola Outbreak in West Africa: Some basic information (Updated)

LATEST UPDATE HERE

UPDATE: The latest numbers do not indicate a weakening of the outbreak. (See list of new cases below. Several graphs have been updated as well)
UPDATE: More detailed discussion of transmission of Ebola
UPDATE: I note with sadness the death of my neighbor (though I did not know him) of Patrick Sawyer, of the Liberian Ministry of Finance, who died in Nigeria of Ebola contracted in Liberia. He was on his way home to Minnesota at the time.

There is an Ebola Outbreak currently underway in several West African countries, mainly Sierra Leone, Liberia, and Guinea. This is the most extreme known Ebola outbreak to date. The first known outbreak of this virus was in 1976, and there have been several instances since then ranging from single cases (which by definition are not outbreaks) to 425 confirmed cases (with 224 deaths in that instance, in Uganda, 2000-2001). The current outbreak is significantly larger with about double that number or more.

There is some confusion in the press (most notably in CNN) about the nature of Ebola and perhaps about some of the details of this outbreak. Here, I want to provide some basic data to help clear some of this up. CNN reported at one point that you can get Ebola only after a person is symptomatic, and (in the same story) at any time a person is infected even if they are not symptomatic. It is probably the case that as long as Ebola is in a person’s system, they can spread it. It is only spread through contact with bodily fluids, but that is not such a hard thing to do; mucus membranes can absorb the virus, as well as cuts or other injuries. It is probably sexually transmittable. It does not appear to be airborne, but bodily fluids that are in or on needles, hospital equipment, etc. can carry the disease to another person.

Another issue with reporting is the difference between suspected cases, likely cases, and confirmed cases. Even within the health community these numbers are all over the place because they are always changing as cases go from suspected to either eliminated or confirmed. Wikipedia and CNN both recently stated that there have been 1,093 human cases with 660 deaths so far. However, this includes both confirmed and suspected cases. There is a good chance that the total number of cases is in fact close to this, but the data are of lower than ideal quality. If we want to look at mortality rates and changes over time in this outbreak, it is better to look at a smaller subset of the better confirmed data. That’s what I’ll do here. But, when looking at the numbers, keep in mind that although most of the data I show in graphics below show several hundred fewer cases than being widely reported, the actual number of people affected by the disease over the last four months or so is probably not only higher than the cleaned up data set but also, likely higher than the reported 1,093. Furthermore, the data I’m using here only go up to July 24th.

One of the most egregious errors at CNN is the frequent statement that Ebola has a 90% death rate, but that the current outbreak has a much lower death rate. This is rubbish. Ebola simply does not have a 90% mortality rate, and stating that the current outbreak is much lower in mortality gives the impression that this particular form of Ebola, or this particular outbreak of the disease, is somehow not as bad as usual. In fact, this outbreak is worse than any previous outbreak for several reasons. For one, it is larger. Also, it seems to be not burning itself out like most previous outbreaks did. Ebola outbreaks in the past have tended to happen in relatively isolated areas, because the population that includes victims is in close proximity to the presumed reservoir of the disease (probably fruit bats) and interacts directly with the intermediate hosts (eg. primates or other mammals that picked up the disease from fruit bats*). But there is plenty of reservoir and intermediate reservoir in some areas near major population areas. Apparently, Ebola broke into the human population in one or more areas of high population density, and this density together with relatively high mobility is allowing the disease to persist.

The following graphs are based on data I collected from the WHO reports. For March, I use only very likely cases, for April through July, I use only confirmed cases (not available for March). And, July does not include the last week for that month (a few more days have been added to this information bringing us to July 23rd, added on July 30th).

The following charts show the total number of cumulative cases conservatively estimated, and total number of cumulative deaths. When the outbreak starts to weaken, we would see a leveling off, but that is not indicated here (UPDATED).

UPDATED_EbolaCumulativeCases2014

The last several reports from WHO (including confirmed, probable, and suspect cases) are as follows:

July 21st through July 23rd: 108 NEW
July 18th through July 20th: 45
July 15th through July 17th: 67
July 13th through July 14th: 18
July 08th through July 12th: 85
July 06th through July 08th: 44
July 03rd through July 06th: 50

The exact time spans for each of these reports may not be the same, but I believe the number of cases do not overlap; each listing is a separate set of new cases. Clearly, for the last several days of available information, there is variation in, but no let up in, the number of new cases.

Looking at the number of new cases reported (and for the most part confirmed) and the number of deaths (the same data as used to make the cumulative graphic above, but by month) we have this (Updated):

EbolaConfirmedCasesAndDeaths2014

Keep in mind that the data for July are short by several days.

Another area where MSM, and for that matter, Wikipedia, could do a better job is in reporting the mortality rate for the disease. Wikipedia states that “The disease has a high death rate: often between 50% and 90%.” This is misleading because the outbreaks with 90% mortality rates are not typical, and the statement seems to be based on a set of data that includes a lot of data points one would do better to ignore. I assume CNN is taking this information (from Wikipedia or elsewhere, which perhaps repeats the Wikipedia claim) and exaggerating slightly when they say that Ebola normally has a 90% mortality rate.

The Ebola affecting people right now in Africa is one of a handful of similar viruses known over a larger geographical range. Some of the deaths found in the larger data set of all known outbreaks are from individuals who showed up in a hospital nowhere near where they got the disease, or laboratory workers. The best way to estimate mortality rates related to the present outbreak in West Africa is to take only field cases — actual outbreaks in normal populations — in Africa only, and to not count “outbreaks” that are not outbreaks because only one person is in the sample.

The following chart compares mortality rates for all of the “outbreaks” listed in Wikipedia page regardless of size of sample, geography, or circumstances, with only those that are African Ebola in the field. The latter set also excludes the present outbreak.

Ebola_Mortality_Rates

Notice that the clean data are bimodal; some outbreaks have mortality rates between 0 and 90%, others between 40 and 60%, and not much in between. Also, there are several in the all-data set that have a mortality rate of zero. This bimodality is not necessarily a persistent statistical characteristic of the sample; I could make it go away by changing the histogram intervals. But it is a convenient place to break the sample into “more severe” and “less severe” outbreaks.

The zero cases in the full data set are all odd cases. Seven are not in Africa and include in some cases lab workers or animal handlers, and most are not African (Zaire type) Ebola. One is a scientist who caught the disease from doing a necropsy on a chimp in the Ivory Coast, examining an outbreak among the non-human primates there. There is one case where the fatality rate is 100%, but this was only one person, and the case was discovered post hoc. We don’t know if anyone else there had the disease. A 90% mortality rate occurred in a remote part of the Congo, with 143 people affected including health care workers. It appears that several individuals contracted the disease butchering non-human primates. This occurred during suboptimal conditions during the Second Congo War. One case of 88% mortality occurred early on in the history of the disease (the second known outbreak) also under very poor conditions. Although the data are too sparse to draw firm conclusions, it seems that the more severe outbreaks in terms of mortality tend to have occurred under more difficult conditions.

Ebola probably has a very high mortality rate when an infected person gets no medical treatment, and a mortality rate closer to 50% when a person quickly gets medical attention. There is no cure, but when a patient is given IV solutions in a hospital setting the chance of survival goes way up. This might suggest that smaller outbreaks that run their course before intervention would have a higher mortality rate, or that the mortality rate would be higher near the beginning of the event. Similarly, one might expect mortality rates to be higher in the early years of Ebola than later, as treatment methods developed.

There is some, but not much, evidence for these effects.

The following chart shows mortality over size of the outbreak, using only the cleaned up data set:

Ebola_Mortality_Rate_Over_Size_Of_Outbreak

There is not a relationship between size of outbreak and mortality rate.

This chart shows the mortality rate over time, for the cleaned up data:

Ebola_Mortality_Rate_Over_Time

This seems to show that lower mortality has been achieved in recent outbreaks, though the statistical significance of this is non existent. But, the data set is small. The above chart also indicates the average morality rate across all of these events, which is 64% across 18 outbreaks. Not “usually 90%” as CNN states.

The following chart shows the approximate mortality rate for the current outbreak by month.

Ebola_Outbrak_2014_Mortality_Rate_By_Month

This is calculated from confirmed or highly likely cases. This is not a true mortality rate because people who got the disease in one month may have died the next month. But it does give an approximate indication of change over time in rates. The rate at the beginning of the outbreak could be high, or this large percentage could be a function of how cases were counted. In any event, this is an indication of higher mortality rates calculated at the beginning of an outbreak, and there are likely two reasons for that high rate, either or both applying in a particular case.

<li>Early in an outbreak a number of people are affected, but live, and don't make it into the data  base because they are not identified; they got sick, got better, and went on their way. Those who died were all or almost all counted. </li>


<li>Early in an outbreak a number of infected people are not treated with the maximum available medical attention, so more of them die.</li>

The current outbreak is settling in at about 60% mortality rate. There is no indication from WHO that the epidemic is slowing down.

UPDATE: Is Ebola Only Transmitted By Symptomatic Individuals?

According to the usual sources (WHO and CDC for example) the following is probably true. When someone gets Ebola, typically, after a while they get sick. This means they show symptoms. If they did not show symptoms they would not be “sick” even if the virus was in them and even if the virus is multiplying in them. Presumably people are infected with a sufficient number of viroids that they become a host for the disease, the virus starts to multiply above some level that makes the person sick, and we can say at that point that they “have Ebola.” This is when the infected person is able to transmit the disease to others through bodily fluids that might come into contact with wounds or mucous surfaces in the downstream patient.

This is what the WHO and CDC literature on Ebola says, and this has lead bloggers and news outlets to state incorrectly that Ebola is only transmitted to others when the person shows symptoms. Unfortunately this is not true in one or possibly two ways.

It appears that people who have had Ebola, live, and get “better” (i.e., their symptoms go away) can still carry Ebola for a period of time, and in this state, they can still transmit it. What has probably happened is their immune system has started to fight the virus enough that it is attenuated in its effects, but it isn’t’ entirely gone yet. Medical personnel like to send someone home only after the virus has cleared. Even so, men who are supposedly virus free by that standard, when sent home after surviving Ebola, are told to avoid sex for several weeks because there is still the possibility of sexual transmission of the virus. Meaning, of course, that the virus is still knocking around in some individuals at this point, and still transmittable. It is not clear how likely that is to happen.

This is very important. Most people would interpret “only transmitted by people showing symptoms” (or words to that effect) when they read it in a news outlet as meaning – well, as meaning exactly what it says. But post-symptomatic patients may still transmit the disease.

Is it possible that pre-symptomatic people can transmit the disease too? Personally I think it is possible even if it is generally unlikely. In a disease that kills over half of those who get it, “unlikely” is not comforting. A small percentage of people who never seemed to have had Ebola, or to have been exposed to it, seem to have antibodies that would probably only develop if exposed to Ebola. Some studies have shown immune reactions to Ebola in those known to have been exposed but also known to not have gotten sick. This is important but not shocking. There are a number of different situations where a normally icky disease that makes you really sick seems to have infected a certain percentage of people asymptomatically. Are these people carriers at some point, i.e., people who have the virus in them, can transmit it to others, but don’t get sick themselves? There is no evidence to suggest that this is the case with Ebola, but the total number of known human cases of Ebola is very small and the conditions for study of the disease in the field very poor, so the safest thing to conclude is that we simply don’t know, but it is also reasonable to say that asymptomatic carriers don’t seem to be a problem, or this would likely be noticed.

The important point here is that there is not a perfect correspondence to being infected and having symptoms, and transmission post-treatment and survival is possible and of sufficient concern that WHO and CDC assume it, so it would be unwise to make too many assumptions about pre-symptomatic transmission.

Imagine you are a health care person addressing an Ebola epidemic. An jet liner flies over a very long flight, say 10 hours long, on Monday. On Friday five people who were on the plane come down with Ebola and you have reason to believe that they were all infected before the flight. Would you determine that it was impossible for the nearly 300 people stuck on a tube with five pre-symptomatic Ebola carriers to become infected? No. You would watch those people and test them.

An additional point to underscore; it has been touched on but not emphasized. The symptoms of Ebola include vomiting and bleeding from places one normally does not bleed. Put another way, the symptoms of Ebola include spreading around bodily fluids. This is often how diseases spread. The disease results in a bodily reaction that spreads the disease (look up “virulence”). So, no matter what, the most likely transmission by far is during the period of symptomatic reaction to the disease, or for some time after death while the virus is still viable. That does not mean that there is no transmission before or after, but it does mean that the most obvious transmission will be from symptomatic patients or recently diseased symptomatic patients.


  • Fruit bats will drop fragments, or stones, of fruit they feed on, sometimes in discrete piles. It is almost impossible to imagine a ground dwelling frugivore, such as a chimp or a duiker, not stopping to munch on this detritus. Since Ebola is spread through bodily fluid contact and can be spread via mucous membranes, and fruit bat spit counts as a bodily fluid, I’m personally of the opinion that this is how Ebola may often transfer from its natural reservoir, where it seems to exist without harm, to other animals. Of course, I figured this out after having discovered and handled several such piles of fruit bad wadge.