Ebola Patient Zero: What we do, and do not, need to know about an epidemic index case

Whenever there is an infectious disease epidemic there will also be an index case, or patient zero: the first recognized case of the disease in a population; the case that alerts you to the presence of the disease. From an epidemiologic perspective, identifying this case is critical because it can provide really important information. How the index case got infected can offer insight into the pathogen's natural reservoirs or modes of transmission, and can also help clarify at what point in disease progression the patient was infectious and how the disease initially moved through the population. All are critical in helping define strategies for future epidemic prevention, control and health care approaches. For these reasons there are things we need to know about an index case. We need to know where they lived, where they went and what they did on the days they might have become infected. Who did they have contact with? When did symptoms start? What did they eat? Did anything unusual happen? Did they go hunting? Was there an insect or animal bite? An injury? A fall? A swim? Who helped them? Are they sick now? These are all important and can help pinpoint the original source of infection.

But do we actually need a name?

Epidemics aren't only about hard science. And while learning all we can about the virus and its transmission will allow us to better fight future epidemics, we shouldn't neglect the human element in the pursuit of knowledge. We have numbers on graphs and charts: cases, deaths, beds. But these statistics are about people and it's often the human stories that drive us. Maybe that's why we look for the names. But should we look for that name?

Many index cases are known, some even famous. You've heard of Typhoid Mary no doubt? Her real name was Mary Mallon and she was forced into isolation after it was discovered she was the (unintentional) cause of dozens of typhus infections. We also know the names of the index cases for the 2003 SARS, the 1854 cholera, and the 2009 swine flu outbreaks. We even know the name of the very first Ebola index case ever recorded, from the 1976 outbreak.

And now we know the name of the index case in this Ebola epidemic. We have had the information regarding the index case for a while now. We've known it was a child in Guinea and we've known that, as the first family afflicted by this epidemic, their losses were great. But now we've also been given the name of the two-year old child who was Ebola's first victim last year.

Did we need that? Did we need to see the family photos? Did it teach us anything about the epidemic? Did this information give us anything useful or just headlines? Did it serve only to exploit the tragedy of a family that lost everything? Did it do anything useful other than put a name to the epidemic? Did it give us someone to blame?

I believe there are many (maybe most) who will not blame this child or his family, but there are those who will. This tragedy will be replayed again and again and the stigma that's already been borne by the family and community will also be replayed. How can it not? This is the largest, most horrific Ebola epidemic in history. Thousands are dead, more dying and it's not over. Who knows what the final toll will be when all is said and done? We can't know that now, but when we do we will be able to trace it all back to one chance encounter with something infectious; one innocent child, one loving family, one community that had no idea what they were up against. A horrific tragedy in every sense of the word.

And by publishing this precious child's name and family photos for our consumption, have we added to our understanding of the epidemic, or is this a new tragedy - one that we must own?


Heather

Ebola in Texas: Take a Deep Breath Y'all

Alright folks. Here in Texas two nurses have turned up positive for Ebola and it's possible other healthcare professionals who worked with Mr. Duncan, or who will work with the nurses, will turn up infected.

So now what? What does this mean?

Well, We know how Ebola is transmitted and we know how to prevent that transmission. But knowing how, watching a youtube video about it, and putting that knowledge into practice in a frightening real life situation, are very different things.

The reason that personal protective equipment (PPE) works, is because people use it and use it correctly. I really don't think anyone would intentionally treat an Ebola patient in what they knew was an unsafe manner, but there are nuances and subtleties involved with PPE that, if not well understood, can mean the difference between safe and unsafe, and with Ebola the room for error is incredibly small. And while you wouldn't leave the gloves on the shelf when examining an Ebola patient, and you might know that removing contaminated gloves incorrectly is just as dangerous as not wearing them, it's easier to misjudge what it really means to remove those gloves safely than one might think. Without practical experience, it's very easy to think you are doing it correctly.

And Texas Health Presbyterian nurses and doctors got thrown into a very tough situation with a very sick patient and we are hearing that they had no protocols in place. Which also means they hadn't done any real prep in case an Ebola patient showed up. But I doubt that situation is any different than most other US hospitals, so instead of castigating them, we should focus on finding ways to better prepare every US hospital. And I think one of the most important things for hospital supervisors to realize is that thinking that you or your staff are doing it correctly isn't enough. You need to make sure that everyone knows what to do and can do it without fail.

So how do you do this?

Training, drills and testing.

From the beginning of this epidemic, we've been horrified about the number of HCW being infected, and untrained and unsupervised HCWs anywhere are susceptible to infection from an Ebola patient. On October 3rd, Dr. Tom Ksiazek, the most eminent Ebola epidemiologist working today in my opinion, gave a talk about his 6 weeks as the CDC team leader in Sierra Leone and said the biggest problem with PPE (when they had it) where he'd been, was training, especially removal of contaminated PPE and supervision.

And it's clear that, while most US hospitals have the capability of containing Ebola to a handful of cases should it appear, whether they will or won't depends on training and the practical application of what is known to effectively protect against Ebola transmission.

Do HCWs in the US have more training in general than W. Africa? Probably. Are they specifically trained in the dangers unique to the very high profile task of caring for Ebola patients who are exhibiting frightening symptoms and exuding copious amounts of infectious bodily fluids, all while performing medical procedures? Not most of them.

In fact Anthony Fauci, Director of the NIAID, said HCW need more training and that you "gotta have drills". You can't just send an email containing a link to nurses and tell them to learn how to use extensive PPE in their spare time.

So how can you find out if you or your staff are disinfecting correctly, or removing PPE without contaminating yourselves? Someone needs to show you how to do it correctly, let you practice under supervision, then test you. A really effective way to do this is to use a fluorescent powder or liquid that is only visible under UV light. Something like Glo Germ. Toss it around a HCW in full PPE, get it on their gloves and shoe covers and mask - all over the place. Then have them disinfect and remove the PPE as they would in a real life situation. Then illuminate them with the UV light to see what lights up. With Ebola you only need a tiny bit of residual contamination transferred from a finger to an eye to cause an infection.

And then understand that this doesn't necessarily mean that the person was careless or cavalier, but more likely that it's really really really hard to decontaminate and remove contaminated PPE safely. This is why there is a buddy system. This is why training and supervision are paramount.

And if you're a nurse or a doctor and you have any hesitation about whether you're prepared to safely enter an Ebola patient's room, you need to be able to feel like you can bow out without the risk of losing your job. Your supervisor should not only respect your professional assessment, but should applaud you for it.

Can this be contained? Absolutely. But unless someone takes charge and shows people how to do this job safely, there will likely be other HCW infections in the process.

Who should be in charge? Well, hopefully State Public Health Departments will play a role in guidance and training, and hopefully the CDC will also provide some oversight. But if I were a hospital, I would assign a small team of HCW (w/enough for redundancy) specifically to handle potential Ebola patients. This team would be the only staff to have any interaction with any possible Ebola patient, from initial evaluation, to diagnosis and testing and through treatment. This team should be on call and given both on call and hazard pay. And this team should be identified now and trained extensively, before another  Ebola patient arrives at an unprepared hospital door.

But in the meantime I think moving the newest Ebola patient, nurse #2, to Emory is a really great idea. Let THP take a deep breath and regroup, and maybe all of our hospitals can start implementing some protocols that will help us move forward and prevent more infections.


Cheers,

Heather

Why Ebola Airborne Mutation(s) are "Highly Unlikely": Let's Talk Mutation and Natural Selection

Note: This post is not an exhaustive treatise on the evolution or adaptation of filoviruses, but an applicable discussion on certain principles.

When Ebola experts say that mutation to become airborne is “highly unlikely”, they are basing this on what they know, as experts, about Ebola molecular virology, cumulative transmission data and natural selection. While they’ve all said it, I think Heinz Feldmann, one of the foremost experts in Ebola molecular virology, said it best in his interview with Kai Kupferschmidt (17 September 2014):

Q: "There has been speculation that the virus could mutate or has already mutated to spread more easily. How likely is that?"

A: "I don’t think there is any data right now to support that. If you look at the virus sequence, it falls within the normal range of Zaire Ebola strains. Of course any of these mutations could have a dramatic effect, which we don't know right now. But there is nothing obvious that would point to a more transmissible, more virulent virus, or a change of transmission route.

You can speculate in every direction, of course, but I think it should be fact-based, it should be data-based, and I think it makes absolutely no sense to bring in aerosol transmissibility as a potential. I think this is really not helpful, unless you have data to support that."

What he is saying there is that he knows Ebola genetics and he doesn't see anything in the new genetic data that indicate the virus is mutating in that direction. Being an excellent scientist, he also acknowledges that we don’t know what all changes mean yet, but based on the data he sees, there’s no evidence to speculate that this Ebola variant is becoming airborne.

Aside from the genetic data they have, Ebola scientists consider the way in which Ebola is already successfully transmitted, as well as Natural Selection.

So let’s talk about Natural Selection for a little bit. In his 1930 book, “The Genetical Theory of Natural Selection”, Ronald A. Fisher made this important distinction, “Natural Selection is not evolution.” It’s “…a convenient abbreviation for the Theory of Evolution by means of Natural Selection…” We will be coming back to Fisher soon, but I wanted to make sure we were all on the same page. So as far as Natural Selection goes, I think Dr. Laurence Loewe described it really well in his educational piece for Nature (1) when he said, “…selection constantly sorts through the variation that is produced by mutations to select the fit and remove the unfit, while ignoring neutral changes.”

Fitness refers to an organism’s ability to compete in its environment in so far as survival or reproductive ability. Can it eat? Protect itself? Have fit offspring? During replication of any organism’s genetic material mutations are possible. For viruses, the speed of replication makes the rate of mutations higher than for a human.(2)  And mutations can be classified with regard to how they affect the organism’s fitness. When a mutation provides a selective advantage in this regard, it will be selected for; the frequency of the genotype (genetic profile) containing that mutation will increase. If a mutation is deleterious, it will be selected against and the frequency of that genotype will decrease.

So what drives mutation? Well, Natural Selection moves an organism toward an adaptive optimum; the point at which the organism would be most fit in its environment. This doesn't mean that Natural Selection causes mutations, but that it determines whether or not a mutation would be kept or discarded. And Fisher thought this occurred in small steps rather than in large leaps. He thought that small advantageous mutations would happen more often than large ones, because large mutations would be more likely to have negative side effects. Well, a group studying RNA viruses actually found evidence to support this theory: they showed “…that adaptation proceeds by multiple mutations, but that among the set of all possible mutations, adaptation proceeds by the subset of mutations with small effects.”(2)

This supports what Ebola experts have said, that it’s not likely that a single mutation would cause this virus to go airborne, and the likelihood of the virus acquiring all the needed mutations at the same time is extremely low.

In addition, there’s no selective advantage to becoming airborne for Ebola. It is clear that Ebola’s current mode of transmission is working well. The virus is spreading and reproducing successfully. This means there is no selective pressure on the virus to keep any mutations that might confer airborne transmission, especially when this kind of significant change would most likely bring with it some serious deleterious side effects. And while some argue that this is the first time Ebola has been replicating to this extent in humans, we need to keep in mind that it’s been doing this for far longer in the wild in the primate species it infects and in its bat reservoir host. And yet, this mutation hasn't happened.

[edit 10/6/14]: WHO agrees with me and has also pointed out today, that viruses entirely changing their transmission mode is not something we've seen before. They must have read my blog. ;-)]  

So, can we say it's impossible? No. But I'm not losing any sleep over it.

Cheers,

Heather

References

1) Loewe, L. (2008) Negative selection. Nature Education1(1):59

2) John W. Drake and John J. Holland. Mutation rates amongRNA viruses.1999. PNAS. 96:24 ; 13910–13913

3) Burch, C. L., & Chao, L. Evolution by small steps andrugged landscapes in the RNA virus phi6. 1999. Genetics 151, 921–927

Not Tonight Dear, I Had Ebola

Edit 9/28/14

I've received some very valuable feedback on this post and I agree that I should have started off with the science behind my opinion and included references. I intended to include references when I posted it, but got distracted and then forgot they weren't there. But without a rundown of what we know regarding infectious semen of surviving men, it wouldn't have been all that helpful. This is what happens when I write out of frustration and post while multi-tasking. Lesson learned.

I apologize and have edited the post to correct this. I've added references and a section with the heading "So what does science tell us about this topic" with a summary of what we know about infectious semen and transmission among survivors. I also realized I should have used the word “unprotected” in the sentence that really drives home the entire point of this post, and you will find that this sentence now has the word *unprotected* in asterisks in the text.

In addition, I added a final point regarding prostitutes (as a post script), based on a discussion on reddit. I am thrilled that this post has engendered so much discussion and I hope these changes have made it a bit clearer. I would also invite you to feel free to begin discussions here. As ever, thanks for stopping by!

Heather

Original Post:

I have fielded a lot of questions regarding Ebola virus in the semen of survivors lately and the
preponderance of people claiming this is a significant source of Ebola transmission is staggering. There is great concern and fear over this. Someone on Twitter was even genuinely concerned that these male survivors are "new highly infectious vectors" that weren't being calculated into projected disease spread. I'm a bit speechless really. Ok, maybe not that speechless.

And last night it was raging on Twitter:
Science based #Ebola horror: survivors have infectious semen for months

Maybe it's under the radar?

In large urbans after millions infected, who knows?

Counseling people on the dangers of sex post-Ebola is great but we know how people are. Who's to say they are obeying doctors orders about this?

So what does the science tell us about this topic? (added 9/28/14) Well, what we do know is from previous outbreaks and follow up with recovered patients. These are the scientific facts upon which my opinions on this are based:

• Evidence of Ebola virus can be found in semen up to 91 days post disease onset (1, 2, 3, 4)
• Not all surviving men have detectable virus in their semen.(2)
• Of those who do, not all of them have it there for 91 days. Some have been found negative at 45 days.(2)
• Men who’ve recovered are counseled by their physicians about the dangers of transmitting Ebola to sexual partners through unprotected sex. (3)
• One study found indirect evidence that one woman may have gotten Ebola from sex, but they could not confirm that she actually had Ebola, or that she got it from sex. (1)
• There is anecdotal evidence that one woman got Ebola from sex during this epidemic
• Dr. Barbara Knust, an epidemiologist at the Centers of Disease Control and Prevention answered this question for NPR and said this: “Ebola is spread only by people exhibiting symptoms and through direct contact with bodily fluids. Once a person recovers from Ebola virus disease, he or she is no longer shedding virus, and thus is not contagious. In past Ebola outbreaks, follow-up studies of patients who have recovered from Ebola and their contacts found no evidence that the Ebola virus was spread from a recovered patient to their close contacts.”
• And in response to the specific question about semen:
• “Therefore, male survivors of Ebola are advised to avoid having sex for three months or to use condoms. Semen and breast milk are not the primary means by which Ebola is transmitted. The virus is primarily transmitted via blood, sweat, feces and vomit.”
• Dr. William Schaffner, a professor of preventive medicine and infectious diseases at Vanderbilt University Medical Center in Nashville, Tennessee had this to say of it. "Of all the modes of transmission, that's going to be the last," Schaffner told Live Science. "It's a little like asking me, 'If we're all going to go from New York to San Francisco, will one of us walk?' That doesn't happen too often."

Are we on the same page now?
Great.

OK. Let's think about this for a minute. No I mean really think about it. Let's think about the average male survivor in West Africa, what he's been through, who he may have lost to Ebola and how he's feeling physically after battling for his life either at home or in a terrifying Ebola ward. Are you thinking? Really thinking?

How would you feel?

Let's say, worst case scenario this man lost some loved ones, family members or friends. He most likely tried to help or watched at least one of those die. Then he got sick himself and ended up in an Ebola ward. He was terrified and thought he would die. But he didn't. He survived and was released. (read about one man's Ebola survival tale that depicts this clearly.)

So is this where you think the party begins? I hardly think so. This is just the beginning of a whole new set of problems for this guy.

This man has to go back home and continue to recover. Recovery from Ebola hemorrhagic fever takes time, sometimes a lot of it. (And yes, I know we call it Ebola virus disease now, but that does little to communicate the severity of this condition, so I'm sticking with EHF - check out the diagram on the right to see what I mean).

Most likely he'll be welcomed from a distance by any family he has left. Do you really think the single ladies are lining up to give him a Hero's welcome? If they were, do you really think he'd be in the mood? You think maybe he will need some time to cope with what he's been through and with what he's lost?

What are the chances he lost his wife if he had one? Pretty good, I'd say. If both got sick, if at least 50% die and he survived. Even if he didn't lose her, do you think he's not imagining what might happen to her if he gave her Ebola through sex? Do you really think, after everything he's been through and seen, with more and more bodies, and more and more people turned away from treatment centers, that he's going to actually feel like having sex, let alone risk someone's life for it?

Let's say the man is single and has lost no one close to him. Do you think the ladies will be lining up for him either? Do you think he hasn't seen and experienced the same kind of hell? Do you really think that, in the middle of the death, loss, hopelessness and terror of the worst Ebola epidemic the world has ever seen, he doesn't care if he infects another person?

In voicing these concerns, do you have any idea how ugly the assumptions you've made about the character of Ebola survivors truly are?

Survivors are being scorned, avoided and worse. Ebola volunteers are being murdered out of fear and ignorance. Do you really think surviving men, men who are still physically and emotionally recovering, are having enough *unprotected* sex while infectious to be a significant source of transmission?

I don't. I think for the most part these men are exhausted and scared. I think they wish they were stronger so they could help more. I think they are worried about providing for themselves and their families while being isolated within cities that aren't functioning well. I think they are thinking about those they infected while they were sick, wondering who among them will die and when.

I keep saying this because it bears repeating: there's no need to look for Zebras here. The out-of-control transmission of Ebola virus in this epidemic is from the well known and documented routes of transmission, while people are sick and symptomatic, not after they've recovered. Why argue for anything else and add to the already traumatized and stigmatized survivor's burden?

We can do better than that.

We must do better than that.


Pathogen Scribe


Post Script:

This discussion continues on reddit and like I said has provided valuable feedback. I’d like to address one particular comment in response to this post:

"I think Heather underestimates the extent to which the "comfort" of a woman has become habitual to many men. A Couple of weeks after being "cured", an over-stressed man might very well revert to that familiar source of psychological balm. She assumes a setting in which potential partners know the survivor, not an urban setting. Infection of prostitutes is not out of the question.”

I would like to take this opportunity first to say thanks for reading and for commenting. And you’re right I should have addressed the idea of prostitutes. However, it would not have changed my point. In fact, if you really think this will cause transmission via semen to be a significant source of transmission (the point of the post) then these are the assumptions you’ve made:

1) A majority of men who’ve recovered from Ebola will forego doctor’s orders and risk infecting others, including prostitutes, because they want the “psychological balm” of unprotected sex more than they want to stop the spread of Ebola.

2) These men are also willing to risk any of the other sexually transmitted diseases that can be spread by unprotected sex with strangers or prostitutes.

3) The women in question, including prostitutes won’t demand the use of protection during sex with a stranger.

And you’re assuming that enough of this will happen to make the spread of Ebola through semen a significant mode of transmission.

Like I said before, we can do better.

References

1) Alexander K. Rowe, Jeanne Bertolli, Ali S. Khan,Rose Mukunu, J. J. Muyembe-Tamfum, David Bressler, A. J. Williams, C. J.Peters, Luis Rodriguez, Heinz Feldmann, Stuart T. Nichol, Pierre E. Rollin andThomas G. Ksiazek for the Commission de Lutte contre les Epidémies à KikwitClinical,virologic, and immunologic follow-up of convalescent Ebola hemorrhagic feverpatients and their household contacts, Kikwit, Democratic Republic of theCongo. Commission de Lutte contre les Epidemies à Kikwit. J Infect Dis 1999;179(Suppl 1):S28-35.

2) Daniel G. Bausch, Jonathan S. Towner, Scott F.Dowell, Felix Kaducu4, Matthew Lukwiya, Anthony Sanchez, Stuart T. Nichol, Thomas G. Ksiazek and Pierre E.Rollin. Assessment of the Risk of Ebola Virus Transmission from Bodily Fluidsand Fomites. J Infect Dis. (2007) 196 (Supplement 2): S142-S147.

3) R.T Emond, B Evans, ET Bowen, and G Lloyd. Br MedJ. Aug 27, 1977; 2(6086): 541-544. A case of Ebola virus infection.

4) L. L. Rodriguez, A. De Roo, Y. Guimard, S. G. Trappier,A. Sanchez, D. Bressler, A. J. Williams, A. K. Rowe, J. Bertolli, A. S. Khan,T. G. Ksiazek, C. J. Peters and S. T. Nichol. Persistence and Genetic Stabilityof Ebola Virus during the Outbreak in Kikwit, Democratic Republic of the Congo,1995. J Infect Dis. (1999) 179 (Supplement 1): S170-S176.

Ebola Convalescent Serum: It's No Magic Bullet

Hello Dear Friends,

There have been many questions since Dr. C.J. Peters was quoted here (9/8/14) saying that convalescent serum from Ebola survivors was unlikely to help treat patients. In this post I go into detail about the data we have that supports this statement. In a future post I will discuss the why of it.

OK. Much of what's been said in the media and by scientists gives the illusion that the effectiveness of Ebola convalescent blood as a treatment for Ebola virus disease is an established and recognized fact. WHO's endorsement and the New York Times article on it has, I think, given people some false hope. Don't get me wrong. West Africa is in a tough spot and I understand why it's being tried. Why not? What else do we have to offer these people? But that doesn't mean it will work. And while I strongly encourage doing everything we can think of to help people, in a situation with limited resources we should focus on those options with the most data to support them and avoid things that might make the situation worse. Since the WHO's announcement, survivor blood has become a hot commodity and now there's a black market for it. How many will suffer a second time because others will surely go to great lengths to get their blood? Blood that will most likely turn out to be unhelpful. But unfortunately, most looking at this situation (like me before I researched it) only know that convalescent serum can work really well for some viruses so they assume it's worth trying. Unfortunately all viruses are not created equal and if those considering this treatment actually looked at the data for Ebola they would see that it tells us this new treatment strategy will almost certainly fail. So let's take a look at this data.

(By the way, if you're confused about names and abbreviations for Ebola viruses you're not alone. For clarification check out Ian Mackay's explanation at Virology Down Under.)

First let's clarify something: what in the heck is "convalescent serum"? To understand what "serum" is, we need to know what blood plasma is, so let me quickly explain. Blood plasma is that light yellow liquid part of the blood that keeps whole blood cells in suspension (keeps them from settling). Plasma contains a lot of important things including, but not limited to, dissolved proteins, glucose, hormones and clotting factors. Blood plasma without the clotting factors is called "serum". Convalescent serum is then serum from the blood of a person who has recovered (convalesced) from an infection, such as a viral infection. This serum may or may not contain those dissolved proteins that could be helpful to fight an infection such as antibodies. Antibodies are proteins made in response to "foreign" bodies, such as viruses, and can help get rid of them. For more details about how antibodies are made and work read this post. You should also know that giving serum that is thought to confer immunity from one organism to another, is called "passive immunization" or "passive transfer". It's important to note here that convalescent serum can also contain drugs or microorganisms so it must be tested both for safety and effectiveness before giving it as a treatment.

As was mentioned in my Q&A with Dr. Peters, for some viruses such as Junin, the virus that causes Argentine hemorrhagic fever, we know that convalescent serum is very effective and is used on a regular basis(1-3). But what do we really know about the use of convalescent plasma or serum for Ebola patients?

Well what's been touted as hard evidence in the media lately are two specific instances in which Ebola patients were given convalescent serum and survived. Well OK then. We're done here right? Not so fast. Let's take a closer look at these cases.

A huge thank you to Mariella Furrer for allowing me to use this photo. Ms. Furrer is an award winning freelance photojournalist based between Kenya and South Africa who has spent her remarkable career documenting some of the most egregious human rights issues. She also documented the 1995 Kikwit Ebola outbreak. Read more about Mariella on my page dedicated to her and her work.

The first is the 1999 paper by Mupapa et al (4) that describes the treatment of 8 Ebola patients from the 1995 Kikwit outbreak. These patients received blood transfusions of whole blood donated by 5 convalescent patients. The blood was tested and found to have ELISA antibodies against Ebola and no viral antigen was detected. So in this case the patients received whole blood, not just serum, but the principle is the same and 7 of the 8 patients lived. WOW! So that blood really worked!! Well, not necessarily. You see, there's more at work here than just the blood transfusion. The authors of the paper  indicated that those 8 patients not only received blood transfusions, they got better supportive care, and with Ebola supportive care may keep you alive just enough for your body to fight the virus on it's own. In fact, another paper published in 1999, by Sadek et al (5), found that with Ebola, the longer you live the better your chances of survival. Sound obtuse? Well, they made a timeline for patients that included time of symptom onset and time of death or survival and it revealed a striking correlation between length of disease and survival: "In general, patients who survived the disease for at least 1 week had a probability of survival of 30%. The rate increased to ~70% for those who survived the first 2 weeks beyond the onset of symptoms." So when were the blood transfusions done? Well, they were done on day 10 post symptom onset. So those patients already had an increased probability of survival. And after adjusting the data for age, sex, and days after onset of symptoms, there was no statistical evidence of a survival benefit from the blood transfusions. Read the paper. Their methods and stats were robust. Furthermore, another paper discussing the same outbreak (6) had this to say, "Oral or intravenous rehydration, provision of adequate calories through oral food intake, and possibly treatment with antibiotics and antimalarial drugs to prevent infections are probably the most important measures to improve survival among EBO patients."

The second case that's been making the media rounds is that of lone virologist Geoff Platt who in 1976, while working with an unidentified virus that was similar to Marburg, accidentally stuck himself with a needle. You can read the paper about his case here (7), and there's a recent article that includes him here. According to the paper, within 24 hours of the first onset of symptoms he began receiving intramuscular injections of human interferon, a protein made by cells to fight viruses. His course of interferon treatment included 3 million units every 12 hours for 14 days. About 24 hours later he was given his first infusion of convalescent serum taken from patients who'd recovered from the 1976 Yambuku Zaire (now DRC) Ebola Zaire outbreak. It was learned later that the virus he'd been infected with was Ebola Sudan. Geoff recovered and in fact after the first infusion of serum the numbers of Ebola particles in his blood dropped significantly. Wow! That serum really worked!! Well, not so fast. You see, they were determining the amount of virus in his blood (viremia) using a guinea pig assay (2 guinea pigs per point). Because taking blood from an Ebola patient and sticking it into a guinea pig can be a bit scary, they didn't take many samples so the actual data from the viremia assay isn't reliable. So it's possible it didn't have as much of an effect as was deduced. This, combined with the fact that this man received interferon and excellent supportive care, makes it impossible to say definitively that it was the serum from the Zaire survivor that was responsible for his recovery (not to mention we have no evidence that different Ebola species provide cross protection).

So those are the cases being touted as proof that convalescent serum from Ebola patients is exactly what these suffering people need and yet, they don't really tell us that. But there is a lot more evidence that this strategy won't work including:

• During Kikwit outbreak, convalescent serum from Ebola survivors was given to cyncynomolgus macaques and it failed to protect any of the monkeys from challenge with EBOV. (unpublished data C.J.Peters., 1995)

• During Ebola vaccine study in guinea pigs, animals that were protected from lethal challenge were bled and their serum was given to naive animals. The vaccinated guinea pig donors all survived. Their serum failed to protect other guinea pigs; all died after Ebola challenge. (8)

• Passive immunization of cynomolgus macaques with high-titer equine immunoglobulin against Ebola Zaire failed to protect animals from lethal ZEBOV challenge (9,10)

• Passive immunization of rhesus macaques with high-titer anti-EBOV equine immunoglobulin failed to protect any of the animals from a lethal challenge and did not even delay death (P.B.J., unpublished data.)

• Passive transfer of a neutralizing human monoclonal antibody that completely protected guinea pigs against EBOV infection (11) failed to protect rhesus macaques against a lethal EBOV challenge (12).

• Transfusion of convalescent blood from EBOV-immune monkeys did not protect naive animals from challenge with EBOV, even though the transfused monkeys had as much antibody as those with effective vaccination. (13). This experiment was done on the off chance that the Kikwit donors had activated lymphocytes or some other substance in their whole blood that provided protection.

So when Dr. Peters said that there wasn't much evidence to support that Ebola convalescent serum would be effective, but that there was quite a bit of evidence to support that it would not, what I've outlined above is what he meant. And Tom Geisbert's group summed it up very nicely in their 2007 paper (13):

"However, the results of the present study, which used immune primate blood, joins the preponderance of published study results suggesting that immunotherapy will not be a shortcut to the solution. Given these discouraging results and the risks of transmitting infection, whole blood transfusions, even under desperate epidemic conditions, seem unwarranted."

As desperate as we are for a way to help these patients, we simply have no solid platform from which to proclaim Ebola survivor blood as effective therapy. With a black market for blood, my fear is that already stigmatized survivors will be further targeted. We have a responsibility to make sure people are informed. 

Cheers,

Pathogen Scribe


Postscript: C.J. Peters Take on This Post:

"I agree with [Pathogen Scribe]. During the Kikwit episode we were harangued to give plasma or have intravenous IgG prepared and I resisted because it diluted our other efforts in a time of scarce resources.  One should also consider that the oldest strain of HIV1 was isolated by Joe McCormick from Ebola convalescent plasma drawn for potential therapy before we knew anything about that virus.  There are also the usual considerations for problems with transfused plasma: antibodies against recipient blood cell antigens, aggregation of IgG activating complement, bacterial contamination, etc.  If plasma is harvested and returned to the developed world for testing and processing into pooled IgG there is the delay and also the problem of recipients reacting to aggregates in the plasma. 
            It seems much more valuable to look down another avenue for therapeutic modalities.  Pooling 3 human monoclonal antibodies to the Ebola glycoprotein with each reacting with a different epitope (14) has been tested in macaques.   When the recombinant vectors are grown in their tobacco leaf substrate and the immunoglobulins purified, this cocktail (ZMapp ) protects macaques (15) and would have a chance with infected humans.  There is also an antisense RNA and several antivirals which might be effective.  And don’t forget the use of anticoagulants such as activated protein C and nematode anticoagulant protein c2 that have had a sparing effect in non-human primates, suggesting that they or other substances working on the coagulation cascade and/or vascular  endothelium have potential (16, 17)."

Another HUGE thank you to C.J. for his incomparable insight and expertise!!


References

1.) D.A. Enria, A.M. Briggiler, N.J. Fernández, S.C. Levis, J.I.Maiztegui Importance of dose of neutralizing antibodies in treatment ofArgentine hemorrhagic fever with immune plasma. Lancet, ii (8397) (1984), pp.255–256.

2.) DeliaA. Enria, Julio I. Maiztegui. Antiviral treatment of argentine hemorrhagic fever.Antiviral Research Volume 23, Issue 1, January 1994, Pages 23–31.

3.) Delia A. Enria,  AnaM. Briggiler, Zaida Sánchez. Treatment of Argentine hemorrhagic fever. AntiviralResearch Volume 78, Issue 1, April 2008, Pages 132–139.

4.) K. Mupapa, M. Massamba, K. Kibadi, K. Kuvula, A.Bwaka, M. Kipasa, R. Colebunders and J. J. Muyembe-Tamfum on behalf of the International Scientific and Technical Committee. Treatment of Ebola Hemorrhagic Fever with Blood Transfusions from Convalescent Patients. J Infect Dis. (1999) 179 (Supplement 1): S18-S23.

5.) Ramses F. Sadek, Ali S. Khan, Gary Stevens, C. J. Peters and Thomas G. Ksiazek Ebola Hemorrhagic Fever, Democratic Republic of the Congo,1995: Determinants of Survival. J Infect Dis. (1999) 179 (Supplement 1):S24-S27.

6.) Guimard Y, Bwaka MA, Colebunders R, Calain P, MassambaM, De Roo A, Mupapa KD, Kibadi K, Kuvula KJ, Ndaberey DE, Katwiki KR, MapandaBB, Nkuku OB, Fleerackers Y, Van den Enden E, Kipasa MA. Organization ofpatient care during the Ebola hemorrhagic fever epidemic in Kikwit, DemocraticRepublic of the Congo, 1995. J Infect Dis. 1999 Feb;179 Suppl 1:S268-73.

7.) R.T Emond, B Evans, ET Bowen, and G Lloyd. Br Med J. Aug 27, 1977; 2(6086): 541-544. A case of Ebola virus infection.

8.) Xu L, Sanchez A, Yang Z, Zaki SR, Nabel EG, Nichol ST, Nabel GJ. Immunization for Ebola virus infection. Nat Med. 1998 Jan;4(1):37-42.

9.) Jahrling PB, Geisbert J, Swearengen JR, et al. Passive immunization of Ebola virus-infected cynomolgus monkeys with immunoglobulin from hyperimmune horses. Arch Virol Suppl 1996;11:135-40.

10.) Jahrling PB, Geisbert TW, Geisbert JB, et al. Evaluation of immune globulin and recombinant interferon-α2b for treatment of experimental Ebola virus infections. J Infect Dis 1999;179((Suppl 1)):S224-34.

11.) Parren PWHI, Geisbert TW, Maruyama T, Jahrling PB, Burton DR. Pre- and postexposure prophylaxis of Ebola virus infection in an animal model by passive transfer of a neutralizing human antibody. J Virol 2002;76:6408-12.

12.) Oswald WB, Geisbert TW, Davis KJ, Geisbert JB,Sullivan NJ, et al. (2007) Neutralizing Antibody Fails to Impact the Course of Ebola Virus Infection in Monkeys. PLoS Pathog 3(1): e9. 

13.) Peter B. Jahrling, Joan B. Geisbert, James R.Swearengen, Thomas Larsen and Thomas W. Geisbert. Ebola Hemorrhagic Fever: Evaluation of Passive  Immunotherapy in Nonhuman Primates J Infect Dis. (2007) 196 (Supplement 2): S400-S403.

14.) Bale S1, Dias JM, Fusco ML, Hashiguchi T, Wong AC, Liu T,Keuhne AI, Li S, Woods VL Jr, Chandran K, Dye JM, Saphire EO. Structural basisfor differential neutralization of ebolaviruses. Viruses. 2012 Apr;4(4):447-70.doi: 10.3390/v4040447. Epub 2012 Apr 5

15.) Xiangguo Qiu, Gary Wong, Jonathan Audet, AlexanderBello, Lisa Fernando, Judie B. Alimonti, Hugues Fausther-Bovendo, Haiyan Wei, Jenna Aviles, Ernie Hiatt, AshleyJohnson, Josh Morton, Kelsi Swope, Ognian Bohorov, Natasha Bohorova, CharlesGoodman, Do Kim, Michael H. Pauly, Jesus Velasco, James Pettitt,    Gene G. Olinger, Kevin Whaley, Bianli Xu, James E. Strong, LarryZeitlin & Gary P. Kobinger. Reversionof advanced Ebola virus disease in nonhuman primates with ZMapp. Nature (2014) Publishedonline 29 August 2014.

16.) Hensley LE1, Stevens EL, Yan SB, Geisbert JB, Macias WL,Larsen T, Daddario-DiCaprio KM, Cassell GH, Jahrling PB, Geisbert TW. Recombinanthuman activated protein C for the postexposure treatment of Ebola hemorrhagicfever. J Infect Dis. 2007 Nov 15;196 Suppl 2:S390-9.

17.) Geisbert TW1, Hensley LE, Jahrling PB, Larsen T, GeisbertJB, Paragas J, Young HA, Fredeking TM, Rote WE, Vlasuk GP. Treatment of Ebolavirus infection with a recombinant inhibitor of factor VIIa/tissue factor: astudy in rhesus monkeys. Lancet. 2003 Dec 13;362(9400):1953-8.

Ebola Q & A with Dr. C.J. Peters: What My Tweeps Want to Know

Dear Friends,

The response to my Fireside Chat with Dr. C.J. Peters was even better than expected and I got a lot of great feedback from my blog readers and Twitter friends. I'd like to thank all of you for taking the time to read this blog and for engaging in such great dialogue about it. It really adds a rewarding dimension to the whole experience.

Many of you had additional questions for C.J. regarding the current Ebola epidemic. I asked him if he'd mind answering them for you here and he was happy to do so. I had to limit the questions so I selected them on a first-come, first-served basis. Several had the same or similar questions, but if I missed anything you think is critical, let me know and I will add it when I can.  Enjoy!

Our first three questions are from Dr. Ian Mackay, a virologist at the University of Queensland who is also the Keeper for both the site and blog for Virology Down Under. Dr. Mackay can be followed on Twitter: @MackayIM and I recommend it. In fact his was the first blog on my blog roll here.

Dr. Mackay: Given this outbreak is very different from previous ones - because of human factors -does what's needed to control it also have to be different?
Dr. Peters: Nobody knows. There's no indication initially that this EBOV is any more infectious than any other EBOV that we've dealt with, but it's something that should be studied using the control methods that worked with the previous outbreaks. There's no indication they wouldn't work but you gotta look.



Dr. Mackay: Following up on that question, what are the top 3 things that could be done, or done better, to contain this outbreak?
Dr. Peters: 1) More training paramedical people. 2) Provide more PPE 3) Rethink the approach. Should we be concentrating on infected areas or areas adjacent to those infected areas? We could superimpose a map of infected areas over a satellite map of the region and ring the infected areas. The adjacent areas could then be given PPE and training, not to contain it but to get on top of it. And quarantine strategy needs to change. People need to be fed and provided for. There's no panacea, they need more PPE and more equipment and currently the major worry is dealing with problems already there. An adequate response will require the whole world to step in, including the U.S. military who are more than capable of setting up field hospitals for highly infectious diseases. Also helpful would be involving anthropologists to interact with locals and help with communications - like how do you tell people what you need them to do and get them to do it?

Dr. Mackay: Have you had a chance to look at the sequence changes from the Sierra Leone genomes? If so, do any look worrying to you for phenotypic change?
Dr. Peters: We don't have the experience we need to be able to answer this. You can't tell that from the sequence unless you have experience with the given virus and with those sequence changes. We've only recently gotten to a point with influenza where we can predict what's worrisome and that's been studied by many smart people for a long time. When discussing the importance of the human genome project, people said it would provide all the words in the dictionary of human genetics. But that dictionary is only helpful if you have the definitions to go with the words. We don't have all the definitions for EBOV sequences. We just don't have the experience it takes to tell at this point.

Our next two questions are from Stephen Goldstein, ScM. Stephen is a Science News Analyst at Public Health United and a PhD student in virology at the University of Pennsylvania. He can be followed on Twitter: @stgoldst.

Stephen: Do you have any thoughts on the case fatality rate disparities between the affected countries?
Dr. Peters: No. And that's a good question. It may be a situation in which case ascertainment is not accurate, but it may be real.

Stephen: What do you make of the studies showing high seroprevalence for EBOV with no indication of illness? Subclinical infections?
Dr. Peters: I think the IFAs are totally unreliable. I've done them myself for Ebola Zaire and Reston, from monkeys and humans and they didn't tell us anything. They are just unreliable. I don't think it means that there were a bunch of subclinical infections, I think it means the test was unreliable.

(ME: C.J. and I discussed these papers for a bit, as well as his experiences with it. I was surprised to learn that even with really good controls and technique the method really isn't reliable for drawing any kind of conclusion about Ebola in this regard. )

Our next questions come from Michael Owen, a regulatory microbiologist from Washington State. Michael is a biosafety enthusiast who has compiled a nice Ebola resources webpage and he can be followed on Twitter: @owenmp.

Michael: In the field, do Ebola HCW need to collect disinfectants used to decontaminate hospital areas and used PPE? How could you do this?
Dr. Peters: Clorox is readily available and effective so they should use it when possible. People who could get exposed should have the right PPE, but if not, then they need to use what they can. Ethleen Lloyd put together a manual in 1998 to help improvise PPE for VHF in an African setting. It's available for download on the CDC website but they haven't utilized it during this epidemic. We could also face shortages of PPE for this. There were shortages with SARS and it's a possibility.

Michael: Is there a minimum time to wait between complete EVD recovery and harvesting blood from a survivor for passive therapy?
Dr. Peters: This is not known for Ebola, but blood/serum from a survivor won't help here anyway. There's no evidence that it will help, but strong evidence that it won't help. For other viruses it can be critical, such as for the arenavirus Junin, for which it is used effectively on a regular basis. But for Ebola it's just not effective. For Junin, they wait until 3 months after illness to harvest serum for therapy, but they don't know that 3 months is required, they just know that 3 months works.

(ME: I was one of the first to suggest that passive immune therapy might help with this epidemic and I was surprised at this, but now have a better understanding. Because this is currently making headlines I will be addressing it in a post soon.)

One final question I asked, on behalf of the fear-mongering doomsayers on Twitter: :Is this Ebola epidemic a threat to humanity?
Dr. Peters.: No. It may very well decimate Africa. Africa is in real trouble, but it is not a threat to humanity and it won't cause a pandemic.

ME: There. You heard that from the Quintessential Virus Hunter himself. And please don't mistake this for denial that this Ebola epidemic is a global problem...it's definitely a global problem. We've already clearly stated that this is a problem that absolutely requires a global response effort. But that's not the same as claiming it will cause a pandemic or destroy humanity. We good? Good.

A HUGE thank you to my Tweeps who came up with some great questions and an even bigger thank you to C.J., for being so willing to clarify these issues and help us understand this epidemic.

Cheers,

Pathogen Scribe


References

K. Mupapa, M. Massamba, K. Kibadi, K. Kuvula, A.Bwaka, M. Kipasa, R. Colebunders and J. J. Muyembe-Tamfum on behalf of theInternational Scientific and Technical Committee. Treatment of Ebola Hemorrhagic Fever with Blood Transfusions from Convalescent Patients. J InfectDis. (1999) 179 (Supplement 1): S18-S23.

Sullivan NJ1, Sanchez A, Rollin PE, Yang ZY, Nabel GJ.Development of a preventive vaccine for Ebola virus infection in primates. Nature.2000 Nov 30;408(6812):605-9.

Wendelien B Oswald, Peter B. Jahrling, Joan B. Geisbert,James R. Swearengen, Thomas Larsen and Thomas W. Geisbert. Ebola HemorrhagicFever: Evaluation of Passive  Immunotherapy in Nonhuman Primates J InfectDis. (2007) 196 (Supplement 2): S400-S403.

Oswald WB, Geisbert TW, Davis KJ, Geisbert JB,Sullivan NJ, et al. (2007) Neutralizing Antibody Fails to Impact the Course of Ebola Virus Infection in Monkeys. PLoS Pathog 3(1): e9. 

Ebola PPE: How the 1995 Kikwit Outbreak Taught Us to Dress for Ebola

Hi Friends,

Well, we've beaten the airborne Ebola angle into the ground but there is still a lot of confusion about what PPE (personal protective equipment) is actually necessary to protect oneself in an Ebola epidemic. It's a fair concern and I think it really depends on where you are. Risk in a Liberian clinic that's overrun with patients and only a few HCW (health care workers) is much higher than in a fully staffed modern western hospital with caregivers who are well rested and highly trained. In that case, it's not the virus that dictates precautions, so much as the environment. But what do you really need, in a real world epidemic situation, to be protected from Ebola? Well, this question has already been answered.

In 1995, the town of Kikwit, Democratic Republic of the Congo and surrounding villages were the epicenter of a serious Ebola outbreak between January and June. During this outbreak 317 people were infected and 245 people lost their lives. In May of that year an international team was called in to help. This team did everything they could to effectively intervene: they went house-to house searching for patients, reviewed hospital and dispensary logs, performed retrospective contact tracing and interviewed everyone involved. One of the most interesting things to note about this outbreak is that a close look at the case definition showed that merely dying during the outbreak was as good a definition as any, with a 95% predictor of Ebola.

In Kikwit, there were two powerful ways by which aerosol transmission of Ebola was ruled out and the necessary PPE was defined.

The first of these was through transmission data collected from patients and family members. Once all the information was in, it was clear that only the person who took care of an Ebola patient got infected. There were zero cases of people becoming infected without direct contact with an Ebola patient. Zero. This is taken from the paper published on it by Dowell et al 1999:

"All secondary cases had direct physical contact with the ill person (rate ratio [RR], undefined; P,.001), and among those with direct contact, exposure to body fluids conferred additional risk (RR, 3.6; 95% confidence interval[CI], 1.9-6.8). None of the 78 household members who had no physical contact with the case during the clinical illness were infected (upper 95% CI, 4%)"

Did you catch that? Every secondary case was due to direct contact with a symptomatic Ebola patient. This is why it's so frustrating to see people in W. Africa without gloves, wearing respirators or covering their mouths and noses with their t-shirt, like this man in a WHO photo. They clearly don't know where the real danger is and we're not effectively helping them understand it.

The second way in which aerosol transmission was ruled out in Kikwit was by the way they contained it. When Pierre Rollin got to the Kikwit General Hospital it was a mess. There were contaminated needles scattered around the floors, blood and other bodily fluids smeared everywhere. It was filthy and patients weren't being treated. No one was providing supportive care because they were afraid to start an IV or give an injection. Pierre initiated and supervised clean-up efforts, starting with PPE, and it got the outbreak under control. He gave the health care workers and family members the basics, including gowns, surgical masks and gloves and once that was implemented the transmission stopped. It. Stopped. The only case that occurred in that outbreak after that, occurred in a small nun-run hospital outside of Kikwit.

They didn't have tyvek suits and PAPRs. All they had was protection from liquids, not aerosols, and they didn't get any more infections. This was striking evidence that Ebola is not airborne. It also argues that when the basics are used early and used correctly, Ebola can be contained. This was also the case for the Marburg outbreak in the DRC that occurred from 1998-2000. For me, this just illustrates how seriously under supplied W. Africa is. Had basic PPE been available at the beginning of this epidemic, things would have been different. But now we're behind it, unable to catch up and terrified people are lying about exposure and fleeing the area. Because of this, Ebola is going to keep killing a lot of people in Africa.

There have also been three other Ebola cases treated in modern western hospitals that support this basic PPE requirement. Before Kikwit, in 1994, a 34 year old female veterinarian working with a group studying chimpanzees in Tai Forest, Côte d'Ivoire, performed a necropsy on a dead wild chimp. Eight days later she got sick and was flown back to Switzerland and treated for what they suspected was Yellow Fever. She was cared for with no special precautions and she recovered. A sample from her was sent to the Pasteur Institute where it tested positive for Yellow Fever. So the sample was given to Bernard Le Guenno, a noted hemorrhagic fever virologist, so that he could isolate Yellow Fever for confirmation. Bernard did virus isolation but he didn't get Yellow Fever, he got Ebola. The Tai Forest species. Oops. By then, the patient had recovered and there were no secondary cases. 

The other two cases were in Johannesburg, S. Africa. A physician treating Ebola patients in an outbreak in Gabon in October of 1996 got infected and flew to Johannesburg without telling anyone. He was cared for at the Morningside Medi Clinic and in November recovered and returned home. No special precautions were taken for his care. During the placement of a central line in the Gabonese doctor, a nurse was exposed to a lot of blood and she became ill soon after, on November 2nd. By November 9th she'd not responded to any treatments and her symptoms were consistent with VHF. They suspected Crimean Congo. ***They sent samples to Bob Swanepoel, at what is now called NCID, to test for CCHF and his technician ran it against all VHFs. It turned out to be Ebola. Public Health then stepped in and transferred the patient to Johannesburg Hospital where she was cared for by Guy Richards and his team who used Ebola appropriate PPE. The nurse didn't make it. However, once again, with the initial absence of special precautions, there were no other secondary cases.

So as you can see, there's powerful evidence that basic PPE to protect against fluids is actually enough to protect against Ebola. Unfortunately, in the current outbreak, there are very few HCWs, with very few resources, to care for an exploding numbers of patients. This leads to, and combines with, exhaustion to create an epidemic that's out of control. In addition, the inability to communicate that Ebola is in fluids, but not airborne is seemingly impossible. Many educated Americans I try to explain it to don't get it, so how can we expect a terrified population in the middle of the horror to understand?

The Kikwit Ebola outbreak provided an unprecedented opportunity for us to learn about Ebola in all regards and those involved took advantage of it. They studied and they learned. Experts who worked extremely hard under deplorable conditions published papers, and the real tragedy here is this:
In all of the papers published regarding the Kikwit outbreak, there are recommendations for handling future outbreaks including containment, health care worker safety, patient physical and psychological care, and information campaigns to both educate people and prevent discrimination against survivors. It's all there.



Apparently no one bothered to look for it.


Cheers,

Pathogen Scribe

***this was updated on Sept 7 2014 to include additional specifics that should clear up any confusion about how the nurse was treated or her samples tested. Thanks to Ian Mackay and Raina McIntyre for providing the missing pieces.

References

Scott F. Dowell, RoseMukunu, Thomas G. Ksiazek, Ali S. Khan, Pierre E. Rollin and C. J. Peters forthe Commission de Lutte contre les Epidémies à Kikwit. Transmission of EbolaHemorrhagic Fever: A Study of Risk Factors in Family Members, Kikwit, DemocraticRepublic of the Congo, 1995. J Infect Dis. (1999)179 (Supplement 1): S87-S91.

OyewaleTomori, Jeanne Bertolli, Pierre E. Rollin, Yon Fleerackers, Yves Guimard, AnnDe Roo, Heinz Feldmann, Felicity Burt, Robert Swanepoel, Scott Killian, Ali S.Khan, Kweteminga Tshioko, Mpia Bwaka, Roger Ndambe, C. J. Peters, and Thomas G.Ksiazek. Serologic Survey among Hospital and Health Center Workers during theEbola Hemorrhagic Fever Outbreak in Kikwit, Democratic Republic of the Congo,1995. J Infect Dis. (1999) 179 (Supplement 1): S98-S101.

AliS. Khan, F. Kweteminga Tshioko, David L. Heymann, Bernard Le Guenno, PierreNabeth, Barbara Kerstiëns, Yon Fleerackers, Peter H. Kilmarx, Guenael R.Rodier, Okumi Nkuku, Pierre E. Rollin, Anthony Sanchez, Sherif R. Zaki, RobertSwanepoel, Oyewale Tomori, Stuart T. Nichol, C. J. Peters, J. J.Muyembe-Tamfum, and Thomas G. Ksiazek for the Commission de Lutte contre lesEpidémies à Kikwit. The Reemergence of Ebola Hemorrhagic Fever, DemocraticRepublic of the Congo, 1995. J Infect Dis. (1999) 179 (Supplement 1): S76-S86.

Matthias Borchert, Sabue Mulangu, Pierre Lefèvre, AntoineTshomba, Modeste L. Libande, Amayo Kulidri, Jean-Jacques Muyembe-Tamfum, andPatrick Van der Stuyft. Use of Protective Gear and the Occurrence of OccupationalMarburg Hemorrhagic Fever in Health Workers from Watsa Health Zone, DemocraticRepublic of the Congo. J Infect Dis. (2007) 196 (Supplement 2): S168-S175.

J. J. Muyembe-Tamfum, M. Kipasa, C. Kiyungu and R.Colebunders. Ebola Outbreak in Kikwit, Democratic Republic of the Congo:Discovery and Control Measures. JInfect Dis.(1999) 179 (Supplement 1): S259-S262.

Pierre Formenty, Christophe Hatz,Bernard Le Guenno, Agnés Stoll, Philipp Rogenmoser and Andreas Widmer. Human Infection Due to Ebola Virus, Subtype Côte d'Ivoire: Clinical and BiologicPresentation. J Infect Dis. (1999) 179 (Supplement 1): S48-S53

"Ebolahaemorrhagic fever - South Africa" (PDF). WeeklyEpidemiological Record 1996, 71, 353-360