Jacque writes:

Dr.’s of TWiV,

I listened to TWiV 308: The Running Mad Professor this morning. During the discussion, Dr. Solomon and Dr. Racaniello were discussing different causes of encephalitis. Recently there have been a number of autoimmune disorders discovered that lead to encephalitis. One that Dr. Solomon mentioned was the Anti-NMDA-Receptor autoimmune encephalitis. There is a fantastic book written by a journalist: Susannah Cahalan. This book documents her experience with this disease, and shows how truly horrifying inflammation in the brain can be. This account shows just how little we really understand about the brain and how to go about diagnosing brain disorders. Susannah goes through several doctors getting a number of diagnoses, including: Alcoholism, Schizoaffective Disorder, Schizophrenia, and Bipolar disorder.

On a completely unrelated note, I would like to suggest a “pick of the week” that adds to one of TWiV’s story arcs. http://www.vanityfair.com/vf-hollywood/2014/09/emma-watson-un-speech-feminism. This is the speech that Emma Watson gave to the UN a few weeks ago to kick off the “HeforShe campaign”. This campaign is meant to end sexism, not just against women, but men as well. She is truly a remarkable woman, and an inspiration to women and men alike.

Thanks for all of your great podcasts!
Jacque (pronounced like Jack – ie)

Conall writes:

Hi Vincent et al, I am a medical Virologist from Belfast, Northern Ireland. I don’t manage to catch all the podcasts but I do regularly dip in and out and tend to be attracted to creative titles (you come up with some great titles!). I enjoy TWIV especially when you do stuff that is a bit off the beaten track. I use it as a productive element in my daily commute. I just listened to TWIV 308 Running Mad Professor- your interview with Tom Solomon was great (I once woke him out of bed about a clinical case!) – excellent stuff, especially the discussion on JE.

One correction that I feel is worth making: UK does not currently use oral polio vaccine – we do use inactivated polio vaccine. The UK switch from Sabin to Salk was 2004.

keep up the great work,

Brooke writes:

Greetings, Esteemed Virologists!

I have a question for Dr. Racaniello about his conversation with Dr. Solomon from TWIV 308:

Previously I thought that we needed to switch from the oral vaccine for polio to the inactivated shot because the oral led to shedding of live virus in the stool, but from what you were saying, it seems that the inactivated vaccine also causes live virus to be shed. Is this possibly because poliovirus is spread by fecal-oral contact, while for most of the other vaccines are for bacteria and viruses that are not spread in that way, so they would not replicate and be shed in the stool? And, if that is the case, do you would the same hold true for the rotavirus vaccine, since rotavirus is also spread by the fecal-oral route?

Thanks to you all for these fantastic podcasts!



Dave writes:

I see in the infographic on your site: “Ebola does not spread in water”.

How do we know Ebola isn’t spreading via contaminated water in West Africa?

Obviously, if one drank water directly contaminated by diarrhea, the disease would be transmissible similar to how Ebola is “air-transmissible” under extreme “head-confinement”. Is the story for water-transmission similar – theoretically possible under extreme conditions, but not a practical concern (even in Liberia)? What evidence supports this conclusion?

Even if there are no documented cases linked to water transmission, there are many cases that don’t have a known transmission vector, including those who turn up as a nameless corpse in the streets. If water transmission was playing a role, we could easily ascribe these cases to direct-infection from an “unknown source”. What sort of evidence would we expect to see if Ebola was transmitting through a water-contamination vector?

Thanks for all your hard work,

— Dave

Bill writes:

There has been much political blather over how asymptomatic individuals entering the country from West Africa should be handled. Even returning medical volunteers have been greeted with fear and hostility. Less obvious has been the expectations of those treating ebola victims in hospitals here. Are they not to take public transportation, commercial flights, approach anyone closer than 3 feet ( especially in Maine)? How do they get to work? Does the 21 day clock reset each time they have patient or lab contact? Should they have to wear monitors similar to radiation counters. A new admission on your 20th day would be a downer for you both. Single parents sure wouldn’t want to be involved. Besides a plane trip, what makes these people different? Surely science based criteria and people of good faith can make sensible policies in spite of the politicians. We need to honor people like the folks at Emory canceling their vacations to care for other heroes and make their sacrifice as palatable as possible.

Jeff writes:

Of course healthcare workers involved in dealing with Ebola should wear PPEs. But these scientists (see link below) are “reasoning” (they “believe”) there is a real concern for Ebola spreading through the air. Reading the Virology Blog I see the likelihood of Ebola spreading via respiratory aerosol is highly unlikely, but I think we need more discussion on this. Thanks.


Lance writes:

Dear TWIV team,

I’m getting fed up of hearing yet more speculation on airborne transmission. It’s everywhere!! What I have to say on the subject is this:

Airborne transmission is an epidemiological concept. This is the phenomenon of an infection being spread from one individual to another WITHOUT direct contact, so cases can occur without apparent exposure to another infected case.

Aerosols are the MECHANISM responsible for the epidemiological phenomenon of airborne transmission. How can people become infected from a brief indirect encounter like being in the same subway carriage for 10 minutes? Answer – tiny particles coughed/sneezed out that dehydrate in air becoming so light that they can stay airborne for considerable periods and infect people at a relatively remote distance from the index case.

It is important to understand the epidemiological observation comes first, then the mechanism of aerosol spread arises in order to explain the epidemiology, not the other way around.

Overwhelmingly, Ebola cases report contact with other Ebola cases (remembering nothing in biology is ever 100%).

As you have discussed extensively already, Ebola virus could certainly be propelled through the air and make contact with a mucous membrane such the mouth or respiratory epithelium and be infectious. This is NOT airborne transmission. In drowning there is contact between fluid and respiratory epithelium, and you wouldn’t call drowning an airborne disease, if you’ll forgive the slightly laboured example!

Keep up the good work, I’ve caught up and I’m hooked on every episode of this week in ebolavirus!


Dr Lance Turtle
NIHR clinical lecturer in infectious diseases
Health Protection Research Unit in Emerging & Zoonotic Infections
Institute of Infection and Global Health
University of Liverpool

Stephen writes:

Dear TWiV Team

A few questions, if ebola virus questions aren’t yet the kind that make you sick:

1. Ebola **hemorrhagic** fever: is there evidence that ebola virus is really transmitted by all bodily fluids, or are those bodily fluids contaminated with blood (or plasma) containing the virus? That would seem to fit with the observation that a patient is only infective after beginning to experience symptoms. Even if bleeding is not obvious, capillary leakage into bodily fluids could already have begun by the time a fever is evident. If that’s true, what about the two cases where ebola virus was found in semen long after symptoms abated?

2. Epidemiology: Even in the absence of risk factor questionnaire data, does the epidemiological picture of an outbreak (of any disease) provide evidence about whether the disease is sexually transmitted, pet transmitted, water transmitted, etc.? So, for ebola virus, there are a couple of potential windows for sexual transmission: before symptoms become severe and after symptoms abate. Would that be evident in the epidemiological numbers? You could ask a similar question about pet transmission.

3. More epidemiology: Considering dogs in Africa, I don’t think we’re talking about coddled Shih Tzus in 5th Avenue apartments. The dogs in question may be pets, wandering the streets (if there are streets) or semi feral. Again, wouldn’t dogs as vectors jump out in the epidemiological evidence?

4. Is anyone studying the sociology of comments on ebola virus to TWiV?

Jürgen writes:

Dear Twiv-ers,

I’ve been a listener of twiv (and twip ) since Dickson & Vincent appeared on Omega Tau. I am neither a native speaker nor have a formal education in your field (I am working in software quality assurance), but I keep on listening hoping that sooner or later I’ll end up with feeling that I understand more than 10% per episode ;-). Thanks for all the episodes you have already done – I could listen forever 🙂

Here’s my question: you discuss a lot about the possibility of sexual transmission of ebola, but I wonder how that could be proven considering that there are much simpler means (airborne, direct contact) and that (non-cyber) sexual intercourse would often include these. How likely would it be to find positive proof for an exclusively sexual transmission? After all, this is a horrible epidemic with uncontrollable conditions and often unreliable information.

Greetings from Germany

Ross writes:

Hey there TWiVocytes,

Ross here again, I just had a thought whilst listening to the latest episode, one would think that investigating whether Ebola persists in semen after recovery would be a relatively simple study, in fact if it weren’t for the BS requirements it would be suitable for an honours year student. In the episode you made the recommendation that post Ebola infection that your advice would be to use a condom. Could one not go one step further and recommend that where possible, using the appropriate container one should keep the condom in a fridge until such time as researchers could come back to collect them. One positive about the high number of people affected by the current epidemic is the number of possible data points for such a study. Is the infrastructure just too poor in West Africa to make this feasible? Is storing semen too dangerous? Does this study pose an unacceptable risk to researchers? Let me know what you think.

Regards, Ross

Corona writes:

Hello TWIVer’s,

I’m a new TWIV listener – admittedly sucked in by the Ebola crisis. Love getting the virology/basic science take on Ebola, and have also enjoyed some of the non-Ebola podcasts. You have even inspired me to get more on top of my tropical medicine – I’ve subscribed to the This Week in Parasitism podcast too.
3 things:

Persistence of Ebola virus in semen after it has been cleared from blood and other body fluids and discussion of whether infection has actually occurred by this route when the patient appears clinically cured has come up several times in the podcast. I swore I read something on this in ProMED-mail , and finally found it again for you. It’s basically an anecdote in a BBC news story:

They tell us about a survivor in their community. He came back from the treatment centre, but despite testing negative for the virus infected his girlfriend, who died.

The semen of male Ebola survivors remains contagious for a minimum of seven weeks after infection.

Here’s the ProMED-mail post that quotes this:
11 Sep 2014 Ebola virus disease – West Africa (160): Senegal, Liberia, tests, media
[http://www.promedmail.org/eafr?archiveid=160] this edited version of the BBC story in ProMed mail makes it look like the MSF people report the survivor in their community infecting his girlfriend. The full BBC story doesn’t juxtapose MSF…but it also doesn’t say who wrote the first person report:
Here’s a link to the full BBC article:

African Ebola Theories

My husband is from West Africa (a neighboring country, Guinea-Bissau – no Ebola there . . . . yet) and he is convinced Ebola was invented by the US Government and this whole epidemic in West Africa is an experiment gone out of control. I’m sorry to say, most African immigrants here in the US I have talked to about this agree with my husband. The fact that Americans with the disease have so far all recovered, but an African with the disease treated here died also makes many people suspicious. At a local gathering of the Cameroonian immigrant community last weekend they played a video about the “truth” behind Ebola that went into the whole “US government has patented the Ebola virus” thing. Even more disturbing, a doctor introduced and endorsed the video!


Even though all this conspiracy talk from my husband and his friends is frustrating, when I noticed a survivalist podcast on Ebola I couldn’t resist. I figured I would hear some even crazier theories. To my surprise, the survivalist podcast was very sensible – much better than much of the news media. Can’t vouch for his non-Ebola statistics, but overall he really is spot on when it comes to putting this into perspective for the general public in the US. For example in response to hype about the “possibility” that the Ebola virus might mutate and become airborne he talked about how it is “possible that you could step in gum, then step on a scratch off ticket someone threw away and then find out you won 50,000 dollars . . .”
Here’s the link: http://www.thesurvivalpodcast.com/episode-1442-the-reality-and-the-hype-of-ebola

Keep up the good work!
Corona in Portland, OR

Dave writes:

Would it not be a good idea to get Ebola survivors to nurse Ebola victims as (I assume) they will have acquired immunity to the virus. DJL. BSc Pharm.

Adam writes:

Hi TWIE crew,
I’m certain you’ve seen the paper below, and I hope you discuss it a bit on the podcast. I was not too surprised what they found, but I was surprised that no similar study in urban rodent populations has been done before. I’m especially glad that the NYT article on the paper starts off with connecting these findings with the current Ebola epidemic, highlighting the direct importance of research to the public’s well-being.

“Detection of Zoonotic Pathogens and Characterization of Novel Viruses Carried by Commensal Rattus norvegicus in New York City”
I also look forward to your discussions on a second Dallas healthcare worker becoming infected with Ebola, which to me indicates that the first infection may not have been simply a breach in protocol. I look forward to further investigations into the practices and training of the healthcare workers while treating the initial infected patient in Dallas.

It’s also alarming that the second healthcare worker traveled on a commercial flight, albeit before the appearance of symptoms. One discussion I’ve repeatedly had with labmates is how much we know specifically on when an infected individual is contagious. The CDC has stated that patients are not contagious before the onset of symptoms, but what data is this statement based on?

Thanks again for keeping us all up to date and informed!

P.S. The rain and short days have returned to Seattle, making it especially easy to stay late at the lab!

Gemma writes:

So, when they say Ebola is only contagious when the patient is very sick because then the fluids are full of virus. Does it mean that if you get just a few viruses into your body, your body can kill them, so the virus is not that strong? and that if you get a lot, your body could still kill them but they reproduce so fast that you just can’t keep up?

Or is that just something they say so we don’t panic? Or it’s true but for some other reason?

Sorry I’m already asking, but always wondering about that and the CDC has told us so many things already that turned out to be false that I really don’t believe them.

Joe writes:

Dear TWIV Team

Lately it seems like you should rename the band to: Vinny and TWIV Pinatas!

I am impressed with your patience in responding to some very uninformed email. This is a classic example of why Risk Communication is not for Wimps! While you all have been showing extreme patience and politeness, I have been yelling at my Ipod for some of these folks to:

GROW THE HELL UP and get out of their fantasy world.

You have been demonstrating the clear difference between having a Scientific Discussion and a Political Argument. You raise a topic and discuss the data, ALL the data and look for data that disagrees with your premise. The folks writing the argumentative emails are determined to get you to agree with their world view. They propose an extreme idea, provide some small selected data set to support their theory and demand everyone agree with them and their TRUTH. My 20+ years of dealing with the public on risk have convinced me that the 80/20 rule applies. 80% of the people want to have a discussion and learn what they can about an issue. 10% on each extreme end of the debate are determined that they already know the answer and the rest of us are fools for not agreeing with their ideas. Unfortunately the extremists are the noisy ones and shout down most folks who want to engage in the discussion.

The old saying “In God we trust, All others bring data” applies here. This needs to be repeated to these folks until it sinks in. No argument that includes the phrase “It could happen” is based on actual data. Similarly, an argument based on saying “You can’t prove it won’t happen” or on compounding multiple failures of multiple systems to invent a worst case scenario is not actually useful in managing risks. A key concept in risk management is: “Past behavior is the best predictor of future performance”. Yes you can invent crazy scenarios and demand everyone prepare for the worst. Those of us trying to manage preparedness have limited time, money, staff, resources, information, and patience. Basing our decisions on something other than all the data available is a waste and is grossly unprofessional. Perception is NOT reality. Reality is reality, perceptions are still important.

Today we learned that at least a second health care worker in Dallas has been infected. With the limited data available to me from the media, I had been assuming that the first exposure was from an individual failure to follow correct PPE removal practices. This new case makes me wonder if the hospital had good controls in place. Maintaining containment and personal protection is all about the details of using the right gear in the right way in the right order. Using unfamiliar gear can lead to mistakes, taking it off in the wrong order usually leads to contamination, being distracted, agitated, tired or afraid often leads to mistakes. None of what we have seen so far is clear evidence that the transmission threat has changed, it is much more likely that these exposures are a result of human error. If I was investigating this I would first look for signs of increased workloads and decreased staffing in critical areas (just like all of us have experienced in our everyday lives). The first place to look is in their training logs. This is very sad, and very human.

Let me close by suggesting that Vinny should not look at saying someone is ignorant as being an insult, History teaches that recognition of a state of ignorance has preceded every great human discovery. Calling someone stupid is an insult. The difference between Ignorance and Stupidity is that Ignorance is curable. Lets celebrate our ignorance and then set out to cure it by listening with an inquiring mind!

During times of stress I tell my emergency response team to “Don’t forget to breathe” as a way to break the tunnel vision that we are all prone to get.

As always thanks the great podcasts and Don’t forget to breathe!


Brooke writes:
[the subject line of her email read: A new plant virus! No, I’m kidding, this is yet another email about the Ebola virus situation]

A warm greeting to my favourite virologists (And parasitologist, in hopes that Dr. Despommier is there with you)!!

I feel I ought to re-introduce myself- I was the fan-girl that giddily asked Drs. Racaniello and Dove to sign my program at ASM in Boston… and was so giddy, I only realized after asking that I didn’t have an implement for either of you to sign my program. (I attached the picture, as a reminder.)

And I also feel I should apologize for my haggard appearance. Under general circumstances, I will recommend the Friend Street Hostel in Boston as a very nice, comfortable, & safe hostel, however, it happens to be directly across the street from two VERY popular (or so it seemed) nightclubs, whose patrons made their presence known until at least 3:00 or so in the morning.

I suppose that by this point, this could be considered follow-up to follow-up to follow-up (or FU to FU to FU right?), but I am having more & more of an issue with something, which I hope you all can help me with.

I am not a researcher, just a Microbiology Technologist working in the central lab for a hospital system, but like many other people associated with healthcare, I am often consulted by family & friends for advice about medically-related topics.

When the ebolavirus epidemic began in Africa and I was asked by friends & family about how worried they should be about it, I responded that the healthcare facilities and equipment/safeguards here in the U.S. could contain and prevent spread of the virus, and that as long as no one exhibiting symptoms of ebola virus disease gets any bodily fluids on them, they are in no danger whatsoever.

(By the by, to me, the best way to define “airborne” transmission means that if I am sitting in the front of a room, and I am infectious and sneeze; a person in the back of the room could be infected, by just the air currents moving the infectious particles to them. If the only way I would be able to infect someone would be able to sneeze at them directly, that does not seem especially “airborne” to me.)

Then, this whole sequence of events rocketed through the news:

A man leaving Liberia (after he helped transport a woman dying of ebolavirus disease) lied about some stuff on his airline questionnaire, and ended up in Dallas, and started feeling unwell, and went to a hospital, but still didn’t mention the whole “direct contact with an ebolavirus infected individual” thing, until the SECOND time he ended up at the hospital.

Then, that man dies.

Then, a nurse who cared for the man is infected by ebolavirus, because apparently the hospital didn’t instruct the healthcare workers how to properly use the protective equipment they provided.

Then, another nurse who cared for the man is allegedly warned by the hospital to not travel, but does so anyway, and flies from Dallas to Cleveland, then back again.

Then, it is reported that the nurse began feeling unwell, and called the CDC (more than once) to find out if it is ok for her to fly back to Dallas, and apparently employees at the CDC assures the nurse that she is totally ok to fly.

(Sequence of events provided by CNN)
So, honestly, at this point, I’m ready to just throw my hands up in frustration, and yell “WTF!!!!” at the Authorities-That-Be, because how are people supposed to believe us when there is so much ineptitude and discord from all of those who are meant to be giving us assurance and guidance??

How do all of you suggest dealing with this? How can anyone providing evidence-based knowledge on the situation be believed right now, when the “Officials” on the situation can’t seem to get their own act together?


So, it’s 9 C (49 F) here in SE Wisconsin, and areas nearby are reporting fog, according to The Weather Channel. The fall foliage here has been gorgeous, but we’ve passed our peak, and have entered the slow decline to winter, I’m afraid.

(Also, if I could suggest a Listener Pick, I’d like to nominate N. B. Designs on Etsy: https://www.etsy.com/shop/NBDesigns?section_id=5125706&ref=shopsection_leftnav_2

Her shop includes jewelry of petri plates and DNA ladders and Zebrafish embryos (oh, my!!) (plus, also, she includes hedgehogs among her jewelry items. I emailed her a year or so ago encouraging platypi (platypuses?) to be included as well. She said that she was considering the idea. I thought that maybe, if she got the “TWiV Bump”, she might be more inclined to explore that avenue? Here’s to hoping!!) )

Thank you so much for all of the education, information, and amusement you’ve provided during my commutes (I still giggle when I hear “stump-grinding” being brought up, and I can’t hear Dr. Racaniello’s introduction without thinking “black-and-yellow”).

Finally- I miss hearing Dr. Condit’s perspective these last few podcasts… I look forward to when he rejoins the crew!



Marian writes:

1. I have an idea that may help stop the international spread of Ebola virus. Currently, Ebola virus disease is diagnosed first clinically (by symptoms), namely fever, headache, pain, vomiting and more. Then it is diagnosed in laboratory testing for the actual virus chemical. However, there is a gap in time between the moment of human exposure to the virus and the appearance of symptoms. This is the notorious 2-21 day incubation period. During that time the person is not infectious, ie, they do not transmit virus, but it is in their body. This time lag is the reason that virus is spreading undetected in travelers. The reason for the time lag is that the virus grows from probably a tiny inoculum to high enough levels of virus to cause disease. Think about if someone sneezes on you, you don’t get symptoms right away: it takes a few days before you feel sick.

2. During those incubation days, when the virus is reproducing, there is an unseen battle between the virus and your immune system taking place. You are not aware of the battle. Then, if your immune system wins, you never even know it happened. If the virus wins, and your immune system fails, you feel symptoms. For most infectious diseases, there is no test for the incubation period. We are now in an international crisis, so taking temperatures at departure and arrivals is important, but as has been seen, it will not prevent importing virus during the incubation period.

3. I suggest INDIRECT testing for virus growth BEFORE symptoms appear. At the moment is it technically too challenging to find and detect the low and dispersed amounts of virus. However, during the aforementioned battle between the virus and the immune system, there are changes in the body and the immune system that may be detectable before symptoms appear. Something called “Type 1 Interferons” are among the first proteins induced as part of the innate immune response in the beginning of a virus infection. These proteins are well-known and well-studied and human diagnostic kits are commercially available. Just like any other detective work, we should be able to find clues; remnants of battles that may be helpful in the current crisis.

4. There are many other proteins, called pro-inflammatory cytokines, chemokines, pattern recognition receptors and others that change in the early stages of a clinical infection. There are published scientific reports about human proteins that change, either increase or decrease in abundance in the human body during Ebola virus infection, possibly early in the process, possibly even before symptoms appear.

5. Many of these tests are already commercially available. For example: C-reactive protein (CRP) is used as a flag indicating the body’s response to acute and chronic inflammation, myocardial infarction, bacterial infections and other events. A blood test for gamma interferon is used to predict development of active from latent tuberculosis. Any of these tests may be indicative of an Ebola virus infection.

6. In short, fever is too crude a tool to presage infection. I suggest that in the future, earlier hallmarks of infection should be routinely tested.

7. I suggest making these tests available on an investigative, situational, off-label and provisional basis. Such a test could be part of a panel of tests, which now includes country of origin and temperature before entry or departure at international airports. Even if the tests are not FDA approved for CLINICAL human treatment, it might be useful as a preliminary airport screening. Before objections are raised about cost and practicality, this is a simple idea and if it works, would go far towards mitigating the unbridled, unsubstantiated frenzy surrounding an already difficult situation. It is probably relatively inexpensive, considering the costs that are either current or anticipated. It probably could be adapted very easily to a rapid pinprick finger blood test.

Walter writes:

hello TWIV masters, from a soggy late night in Northfield Mass where it is currently 71F / 22C and windless. Please comment on the Liberian Firestone plantation’s response to ebola. If you have already done so, please tell me which podcast episode it was in.


Martin writes:


Don’t you think there is a problem in the identification of the Ebola virus, i.e., identification is squishy, and therefore the numbers are susceptible to political manipulation? You mentioned in the last episode that 15% of the general population there tests antibody positive for Ebola. Let’s see…the population of Liberia is 4.294 million…does that make 644,000 cases of Ebola? (What if the press reported that!)

With respect to PCR, I remember Vincent saying in another context, “Anyone can do PCR, you have to find infectious virus.” Apparently PCR is no good for testing the quantity of virus, not good for testing whether there is a real infection.

So where does that leave us for a scientific diagnosis?

I think the epidemic is mostly a contagion of panic. But we should keep in mind who profits from a nice epidemic– the press, pharma, government agencies, researchers, etc.


Teresa writes:

Hi TWiV team!
Thank you for your podcast! I am a registered nurse and have been an enthusiastic listener for several years now. I love the depth in which you discuss the various topics. Your podcast inspired me to pursue graduate education in public health and epidemiology!

I do have a question about your favorite topic these days….Ebola. Does HIV infection increase susceptibility to Ebola infection? Does it change the mortality rates? I haven’t heard anything about the two viruses together and was wondering if co-infection played any part in the current outbreak. Thank you for being a reliable source of information regarding this Ebola outbreak even though I am sure there are many other things you would rather discuss!

In Seattle, WA, the weather this morning is a pleasant 56F/13C with 76% humidity.

I look forward to many more years of listening!

Sofie writes:

Dear Twiv,

Thank you for a wonderful podcast! You are all doing an amazing job in informing the public.

I am not a virologist, just a simple clinician. I have an M.D. and I’m currently working on a Ph.D. in epidemiology of patients with chronic hepatitis c in Copenhagen, Denmark. I share my office with virologists from the CoHep group headed by Jens Bukh so I hear a little here and there about virology.

I wish a group of M.D.’s would feel inspired by your communication effort and make a similar podcast about medicine. Unfortunately doctors are not always that great at communicating science to the public.

The weather sucks here – as always. Heavy rain and about 12 C.

I only want to make a humble comment and I’m sure you already know this. In the previous podcast the medical anthropologist from the American Museum of Natural History wondered why there hadn’t been more emphasis on the hemorrhagic symptoms of Ebola. Early on in the current epidemic there was an article published in NEJM where the authors discussed whether it should be emphasized through the communication with the public that hemorrhagic symptoms were not the predominant symptoms and emphasizing the term “ebola hemorrhagic fever” could lead to missing the diagnosis of Ebola.
This I thought was a great point since after all a very important part of trying to contain this outbreak is communicating it to the public and health care workers. This was early in the outbreak, however, and the number of patients was small.

Then came the report about the first 9 months of the outbreak, also published in the NEJM, where the sample size was bigger. Here the authors documented that “Specific hemorrhagic symptoms were rarely reported (in <1% to 5.7% of patients). “Unexplained bleeding”, however, was reported in 18.0% of cases.” Unexplained bleeding was reported in 20.2% of cases who died and 11.7% of cases who recovered.
The article is a great read and there is an informative table listing all the clinical symptoms reported and their frequency.

Maybe the fact that specific hemorrhagic symptoms are not that common is a reason why these symptoms have not been emphasized more during the current outbreak?

18% of patients experiencing unexplained bleeding is still a lot of patients but it is not the most frequent symptom (which is fever, fatigue, loss of apetite, vomiting and diarrhea in the studies) and thus an important message to the public is that not all ebola cases look like the misleading, horror pictures from hollywood movies with blood coming out of every orifice.

So thank you again for setting the record straight for everybody willing to learn and educating us all. I really love your show and I cant wait to download the next one and listen to it when I go for a long walk around the lake.

Take care!


P.S. Do you ever consider making your apps for android phones?

Stephen writes:

Dear Climatic Virologists:

Though I’d join the line of people looking for episodes not on Ebola (maybe every other episode?), I’m going to make that harder with a quick follow up. My ears perked up when I heard the discussion about the possibility that simultaneous EVD outbreaks might be caused by environmental factors. I’d recently had a conversation where I and another listener wondered if you twivsters would manage to create even briefly ‘This Weather in Ebola Virology,’ merging two of your major interests. But, unless I wasn’t listening carefully enough, you never named what those environmental factors might be? So, might weather be one of them?

The weather here in Fort Collins is cooling from the summer heat with highs as low as the 50s, and thus viruses here are also winding down; or, at least the risk of West Nile is waning.

Gretchen writes:

Dear TWiV crew,

While I have the utmost respect for your dedication to reading every email that you receive at TWiV let me say as a long-time listener that in recent weeks the show has become repetitive and boring because of it. So much time is spent going over what we already know, and almost nothing new comes out of the conversation. Might I suggest an abbreviated version of follow up for the duration of the ebola panic? For example all questions that come up in this weeks follow up email could be dealt with at once instead of reading every email individually and any useful links that the hosts think listeners would like to see could be listed at the end as a sort of “pics of the follow up”. This would allow more time for you to discuss actual scientific papers instead of simply assuaging the fears of the populace.

I know this email sounds rather critical but I do really enjoy the show and simply look forward to getting back to what made me fall in love with it in the first place. Science.

Thank you so much for your time, both in producing this podcast and reading this email.


Jessie writes:

Hello again, Grand Masters of the TWiV,
we’re glad you liked our handle for you. 🙂

Thank you very much for your thorough responses, wisdom, and encouragement.

I just wanted to follow up to say that your responses were exactly what we were looking for, and exactly why (and how!) we proposed to study it. The truth is that not many people have looked in a controlled and rigorous way (even in animal models), and those that have had only small numbers with which to work – because – as I have been told/scolded – it’s very hard to get those data for primarily social reasons. The Marburg example is pretty clear-cut, which is why we mentioned it (old and in German doesn’t disqualify it). Not to mention that controlling for exposure to others within the community is a huge issue. Though we’ve just published a paper showing how Ebola sequences can be used to infer transmission, so it’s possible the same could be done to control for that.

We of course know that PCR amplification doesn’t mean infectious virus, but what surprised us is we didn’t realize that non-replicating virions could “get lodged” in tissues and remain for for months without being degraded!

Anyhow, last but not least: Re: PCR for active-sense nucleic acid products and burnt out grad students: why not try some single-genome 454/Illumina sequencing methods? That way, you have one template per well and there’s no ambiguity for which strand is the source…? It’s essentially that one round of PCR you’re talking about – with the sensitivity to drop the need for amplification. Not that I’ve ever done it, so I can’t say there aren’t other problems with it, but it may be at least worth it to have a look..!

Happy Sunday and Cheers for a productive week to come,

Yours faithfully,

Jessie + Carmen

Mary writes:

Hail to the TWiV experts,

Has there been research that has focused on the number of Ebola virions for any of the current strains required to cause an infection?

Keep up the informative and witty outreach!

Thank you,

PS: Currently 13ºC, cloudy with calm winds, 87% humidity. Dew point 11.1ºC. Visibility 10 miles.

Tom writes:

Hello TWIV educators and thanks for all the good work you do. I have no background in the sciences other than what we call over here (England), GCSE biology – a very basic understanding from 15 years ago during school. I currently work at a landfill site performing environmental monitoring so there’s no further advancement there either. However, I’ve always had an interest in virology and epidemiology and I enjoy listening to your podcast while I carry out menial tasks at work, educating myself as I go. I started listening just prior to the current Ebola outbreak but I can imagine your listenership will be increasing greatly what with current events. My question, or perhaps request, is thus – would you consider recording a one off special out of sequence with your current episodes that might introduce some of the basics of virology to any new listeners who may not have a great understanding of the field. You certainly have a knack for talking about things in an educational, easy to grasp manner and at no point do you ever seem condescending so I feel that if anyone could help the layman understand how viruses replicate and exactly what makes them so fascinating, it’s you guys. Very rarely do I ever get lost in what you say and I’d consider myself only one step up from a layman, but there’s a few people I know who are and I’d like to point them to you. In London it’s slightly overcast, 16 Celsius and… Not particularly humid. Thanks for all the great work and keep fighting the good fight.
Yours, Tommy G.

Stephen writes:

I expect that you and the team are already aware of this piece, but this Lancet letter is the first mention I’ve heard of the proportion of people who may be infected but unaffected by the virus, and what difference this makes to projections, and to opportunities this may give in the areas of care, and research.

Ebola control: effect of asymptomatic infection and acquired immunity : The Lancet

Hoping that some breakthrough gets TWiV back to its normal routine soon.
It is very good that your special service was already up and running when this came along. (y)

All the best,


Lizi writes:

Hello to the wonderful scientists at Twiv,

Every year for most of my life, my family has visited my relatives across the country for Christmas. This year, my parents told me that we might not go because they are worried about catching Ebola. I am a biology major and I’ve been listening to Twiv for about a year, so I tried to use what I know to reassure them that it’s perfectly safe to fly within the country. I don’t think I was very convincing. What could I tell them to reassure them that we almost certainly won’t get Ebola? By the way, your podcast has inspired me to learn more about virology and I look forward to it every Sunday.

Thank you!
–An avid listener

Stephen writes:

Twiv team,

On TWiV 307 you mentioned that you weren’t sure about filoviruses integrated into bat genomes, but that they were integrated into human genomes, so if they are found in bat genomes it may not be important.

I’m not sure about integration of filovirus-like elements in the human genome, as I haven’t found anything on this. However, in 2010 Taylor et. al. published an article titled “Filoviruses are ancient and integrated into mammalian genomes.” They identified filovirus-like elements in the genomes of bats, rodents, shrews, tenrecs and marsupials. The phylogenetic diversity represented by these animals suggested that filoviruses are tens of millions of years old.

Perhaps most interestingly, some of these filovirus-like elements were transcribed and are homologous to a fragment of the filovirus genome whose expression is known to interfere with the assembly of Ebolavirus.

This bit made me think of the paper you discussed on TWiV 303 regarding integrated Borna virus-like elements in the squirrel genome. It also makes me wonder if this could relate to the ability of bats to serve as a reservoir for ebolaviruses, which may require their ability to restrict replication to some extent. Perhaps you could ask Linfa Wang about this?

Thanks for the great recent run of episodes, though 303, in which you managed to discuss both the Ebola virus outbreak and the aforementioned paper, is my favorite in the recent run.

Gayle writes [re: recombinant vaccines ep 307]

Dear Dr. Racaniello:

In veterinary medicine we have been fortunate to have access to live canarypox-vectored recombinant vaccines against feline leukemia virus and rabies virus for several years. This technology has proven both extremely safe and extremely effective.

In the case of FeLV vaccine, it took us from 90% protection in prior vaccines to 99% protective, which probably meant saving the lives of countless thousands of cats because we really appear to have broken community/herd transmission in a lot of areas now.

When I first came to Los Angeles in 1983, feline leukemia virus infection was epidemic in the local cat population. Development of reliable blood testing helped, but we really didn’t make much ground against it until we got a vaccine. Those vaccines got better over time, but that 10% unprotected gap still allowed the problem to persist. These days it is truly rare for me to see a FeLV positive cat, and it is virtually always in a 100% outdoor or overtly feral cat.

Thank you for your wonderful podcasts. I loved microbiology when I got my B.S. in it long ago, and it’s amazing how the field has become so dominated by genetics.

Keep up the good work!


Caroline writes:

Does infection with the Reston ebola virus give immunity to the Zaire ebola virus?

Beth writes:

Dear TWiV-o-nauts,

My name is Beth, and I’m a second year graduate student in the Microbiology, Immunology, and Cancer Biology program at the University of Minnesota. I study malaria, but as you can imagine my fellow students and I have been talking more about Ebolavirus these days than our own research topics. I really appreciate all the Ebola-themed TWiVs you’ve been doing of late, and I admire your patience in constantly answering the same questions (most notably, is Ebolavirus airborne? No, no, no). Since most of my friends and family are not biologists, I’ve been doing my best to pass all the information I’m learning from your podcasts onto them. I’m a strong believer in that more scientists need to do more to communicate with the public (one of the many reasons I love all the TWiX podcasts), and I feel that the shocking quantity of misinformation in the media about Ebolavirus is a perfect opportunity for us to do just that.

With this in mind, I took the opportunity this morning to get up on my Ebola soap box and do some science communication in an unusual venue- a church service. The pastor was discussing Ebola in her sermon, and at the end of the service I decided to get up and do a PSA (public service announcement) for the congregation, to dispel some of the myths being perpetuated by the media. I hope you don’t mind, but I borrowed (and properly cited) a bunch of information from your podcasts, focusing mainly on two ideas: one, that Ebolavirus is not, nor will become, airborne; and two, that the Ebolavirus outbreak is a sociological issue much more than a virological one. I explained that as scientists we are trained to never say never when it comes to predicting something like a virus changing its lifestyle, but that Ebolavirus becoming airborne is about as likely as pigs flying, and by that point they wouldn’t be pigs anymore. I love this metaphor because not only do people find it funny, but I find it a very clear and understandable way of communicating a point.

Even though many members of the congregation are fairly well educated, so to some extent I was preaching to the choir (in a very literal sense, given that my poor fellow choir members have been hearing me rant about this issue for several weeks now), most people seemed genuinely receptive and happy to hear a virological rather than media-based political perspective on Ebola. I was applauded after my comments, and several people came up to me afterwards saying something along the lines of ‘that was exactly what I needed to hear’. This gives me hope that many non-scientists really are thinking critically about this issue, and that they are willing to listen to the science community about it, rather than subscribe to popular hype.

This brings me to the point of my e-mail. I know that there are thousands of scientists and non-scientists out there listening to this podcast, and getting the best information about Ebola straight from the crack team of Vincent and company. Spread the word on the truths about Ebola that the media is obfuscating! Tell your friends, tell your family, tell random strangers at the bus stop and be good science communicators- consider it your payment back to the taxpayers for funding science research (or not, depending on how successful your last grant application was). In my experience, at least, people are often willing to listen.

Today in Minneapolis it is a sunny 20 Celsius/68 Fahrenheit (heat wave!) with 43% humidity and west winds at 17 kilometers per hour.


Ken writes:

Peter Piot gave a nice talk about Ebola in Oxford 16 October that was recorded:


In response to a question he also said it was extremely unlikely that it could mutate to be transmitted as an aerosol (at 1:09).

Might be a good listeners’ pick.



Ruth writes:

Dear Dr. Racaniello:

I am one of your new podcast listeners.

Just as a way of introduction, I’m 69 years old and my field originally was Scene Design and Lighting (M.A., Northwestern University, 1968). My dad was an OB/GYN and my mother and sister were nurses, so my choice of career was odd. In order to earn a living (which theatre didn’t provide), by the mid-70’s I was doing secretarial work in NYC, and I gravitated toward working for doctors and in hospitals. I’m a great speller and took four years of Latin in high school, so I was a whiz at medical technology. And born into a medical family, all things medical have always been interesting to me. Except blood. Which makes me pass out if I see it on anyone but me.

In 1978, I decided to get my Ph.D. in Theatre History and Criticism at CUNY. I passed all the requirements except the dissertation and then realized that teaching was not going to be for me. I mention this just so you know I was trained in research, although it was nothing like medical research. What that means is that once I get a question about a subject in my head, I have to keep researching the subject. One question always leads to more, as you know.

My favorite hobby has become researching the history of infectious diseases and the story of emerging infectious diseases.

I’ve gotten serious enough so I now follow the “Infectious Diseases” newsletter, which means I was following the current ebola outbreak almost from its very beginning. I was delighted to discover the TWIV podcasts sometime in late September.

Bear in mind that I first listen to your podcasts while I’m doing other work or housework, and THEN I usually listen to that podcast again, with full attention.

In one of the more recent podcasts (I’m sorry, I can’t pinpoint which one), you got annoyed by a comment or journalist on the “mutating to an airborne virus” topic and you said something to this effect: “If ebola is going to mutate, what it’s going to really want to do is figure out a way to keep the host infected longer.”

And I sat up straight and thought, “HUH? Ebola thinks? Viruses think?”

And that really got me stewing over many new questions.

Which led me to discover your “Virology 2014” Columbia lectures on YouTube, which I started watching this weekend. I’m up to the middle of Lecture #3 and realize there’s probably a prerequisite your students have taken that I sure have not. I noticed on your blog that there’s something called “Virology 101” that’s most likely for lay people like me, and I may go and watch that before continuing with the Columbia course. (Columbia, btw, is where my dad got his M.D., in 1929.)

ANYWAY. In Lecture #2 you are very clear that viruses DO NOT THINK. And I certainly am relieved about that!

Moral of the story: Your podcast led me to your blog, which led me to your Columbia course on YouTube, which I’m sure will lead me to much more research, not only about virology, but also about the larger subject of the emergence and history of infectious diseases.

Please keep up the great work!!!

Signed – A new and devoted fan, Ruth

Stephen writes:

I wanted to add a couple of points in the discussion of checking your facts.

In medicine past, tremendous harm was done by various medical practitioners not checking their facts. I believe I’ve read that the airline industry’s procedures made a huge difference: create a checklist, check everything on that list–every time.
If you go into a hospital now, nearly everyone asks your name, date of birth, etc. No health care worker should accept your argument that you already gave all that information to the previous health care worker.

In surgeries, legs to be fixed–or amputated–are marked with big, obvious indicators: Cut Here. Nurses are trained to double check physicians. Blood type is checked on the spot, not read off of a wallet card or iPhone app.

The Dallas ebola virus case is, er, a case in point. The physician–presumably an overworked ER physician–assumed he or she knew what the situation was, and didn’t have to ask again.

I can think of many ways to avoid this, and I assume many are being implemented in ERs throughout the US, and I hope elsewhere. The obvious one: every emergency room rubric must include asking where the patient has been recently, whether it’s in country travel or international travel.

I nominate a term for the act of checking your facts, even if it might be embarrassing: “a racaniello,” as in “He just [performed, did, committed] a racaniello!”


David writes:

Dear TWIV team,

Greetings from Nicaragua. I have been listening to TWIV since April last year, and have now only about 100 TWiV episodes to go. I have enjoyed all TWiV episodes I listened to so far, as well as all TWiP episodes, while I am improving my microbiology knowledge to make sense of TWiM. Thanks for your enduring efforts, they have made my life bearable in a time of turmoil due to private circumstances.

I noticed you were trying to get the pronounciation of Piot’s name right in the latest episode, and as I am of Belgian origin, I would suggest the correct pronounciation is peeyot (go light on the “y”). I included a very short audiofile for further reference as to how I think it would have to be.

I also found some footage today on the web of the 1976 discovery. Although these are just short fragments, I think it gives a good feeling as to how the circumstances were – and probably still are if I can take my own experience and visual memory of my time in Africa into account.


Again thanks for the spectacular educational effort to which I look forward every Sunday evening, sunny greetings from Jinotepe with an early morning temperature of 24 C, humidity of 94% and no wind at all.

Yours sincerely,


Simon writes:

Dear TWiE team,

Firstly I wanted to let you know how excited I was to have my first TWiV email read out on air a couple of months ago. It is a fantastic feeling to be able to form part of the conversation, and I honestly spent the rest of the day with a huge grin on my face.
In my email I had mentioned my desire to come and hang out with you guys during one of your sessions, to which Rich Condit said something along the lines of “Well, where do you live?”. That sounds to me like an open invitation….

Anyway, I am writing to share with you a few articles of interest from the past couple of days. In light of so much of the sensationalist media coverage, I think Vox (a fairly new online media venture) have really gone out of their way to provide a more rational view-point.

They have a dedicated Ebola page (http://www.vox.com/ebola) with a number of articles focused on putting things in perspective….a couple of my recent favorites:

“The Real Lesson of Ebola in Dallas: This virus is very difficult to spread” – http://www.vox.com/2014/10/20/7013357/homas-duncans-fiance-dallas-ebola-virus-outbreak

“This Ohio Man has The Perfect Reaction to Ebola” – www.vox.com/2014/10/20/7022197/ebola-perfect-reaction-ohio-peter-pattakos.

This is the reaction from a man who supposedly visited the same bridal shop as one of the nurses from Dallas, and I quote: “I’m much more likely to be mistakenly killed by a police officer in this country than to be killed by Ebola”

I have thoroughly enjoyed Vincent and Alan’s recent discussions of the merits of a flight ban. If anything, it proves that the podcasts are definitely not scripted and that, like all good scientist, you sometimes have disagreements. I submit for your consideration the following article by Nate Silver, “Why An Ebola Flight Ban Wouldn’t Work” (http://fivethirtyeight.com/datalab/why-an-ebola-flight-ban-wouldnt-work/).

My personal perspective is that I think much more could be done with the resources which would be required to try and implement a likely ineffective flight ban.

Finally, in the New Yorker, there was an article by your friend Richard Preston entitled “The Ebola Wars, How genomics research can help contain the outbreak” (http://www.newyorker.com/magazine/2014/10/27/ebola-wars)

While it was still a little sensationalist (though not as much as you might imagine), not as sciency as I had hoped and often off-topic, I enjoyed it for some of the human stories of the people involved. There was also a very interesting part discussing the possibility of the virus becoming airborne. The question was posed to Professor Eric Lander of the Broad Institute and Human Genome Project:

“That’s like asking the question ‘Can zebras become airborne?’ That would be like saying that a virus that has evolved to have a certain life style, spreading through direct contact, can evolve all of a sudden to have a totally different life style, spreading in dried form through the air. A better question would be ‘Can zebras learn to run faster?’”

Speaking of Dr Lander, I have a pick which probably doesn’t fit the category of pick of the week, but which I would still like to put out there.

Earlier this year I worked my way through Professor Racaniello’s Virology part 1 course. Whilst it was fascinating and I learned a huge amount, I often struggled with some basic cell biology concepts (my last formal bio course was about 15 years ago).

I then came across the Introduction to Biology – The Secret of Life Course on edX, taught by Professor Lander (https://www.edx.org/course/mitx/mitx-7-00x-introduction-biology-secret-1768#.VEaoD-fbFPU).
What a fantastic course and what a great teacher! I highly recommend it to anyone who is keen to learn or brush-up on some basic biochem, genetics, molecular biology, genomics, recombinant DNA etc.

My apologies in advance if you have already covered any of this….I think I am one episode behind.

Thanks again for the excellent podcasts. Next time I will try and find a good non-Ebola topic to give you some variety.

Timothy writes:

Dear TWIVical people,

I’m a long time listener to TWIV and TWIx but haven’t written with a question before.

Listening to your very welcome coverage of the Ebola outbreak in west Africa, and in particular the modeling, it sounds like the critical benchmark is getting 70% of affected patients into beds and isolating them. However I can find no news coverage of exactly where WHO, MSF, and other organizations are in this race or how long it is likely to take to get there. Do you have any good sources of information on this? Obviously the longer it takes, the greater and more difficult an endeavor it will be as the epidemic continues to grow.

On an unrelated note, I would love to hear a TWIV 101 episode all about virus-host co-evolution. Endogenous retroviral DNA and all the latest on what it’s doing in there.

Cheers and thanks for the best science podcast out there,


Mentally at Gale crater, where the temp is -27°C and no rain for some time. 0.25” Hg pressure and sunny skies. Tell Rich to bring sunscreen.

S David writes:

Had my first actually cool sleeping night. Improved sleep. Air quality fluctuating around the margin of good, too, for a few days.

A few weeks back, lots of comments on NPR stories at NPR’s site started flooding in, vacillating among reasonable inquiry, rumor promulgation (Fox like), and frank hysteria, re Ebola.

For some time now, my compulsion has been to put in my two cents worth there. Sometimes I critique the journalism. Sometimes I share wry observations. Sometimes I share from my modestly broad (but shallow) knowledge base, and insist on making sense when reasoning our way through the concerns of the times. I’m fairly good at it.

So anyway, a few weeks back I posted a few comments suggesting that some journalists and some listeners could attain some better understanding if they would check out TWIV podcasting. I cited you as a contributing source of my reason to think I had anything worth saying to say.

I wonder if some of your new listeners may have flowed from that. It’s amazing how many people quietly read the damn thing.

Just taking a moment to brag. Awaiting any actual facts.
Till later,

Justin writes:

Erica Ollmann Saphire at NIH^, last November 11-6-13
Kyle writes:

We created a data-driven view of Ebola outbreak histories with data from CDC and WHO. Feel free to use it as an embed on your site or just as a research tool.

Here’s the link to the Ebola Outbreaks Database: https://ebola-outbreaks.silk.co/

Thanks for reading and look forward to your reply.

Dallas writes:

Dear Wise Men of Science,

It’s likely that the 50% survivors of ebola would be immune to reinfection. If they are, there would be a pool of thousands of people who could be trained for basic nursing and other functions without wearing the isolation suits that drastically limit people’s ability to actually work. Training local survivors would bypass a lot of cultural issues, while increasing the human resource capability of the local community and providing desperately needed employment.

The clean up problem associated with patients’ vomit and diarrhea when these body fluids are pathogenic would severely strain a resource limited area of the world. This part of cleanup could be fairly critical, but might take minimal training for people with immunity. A training program would begin with clean up and bed pan duties and progress to training survivors to accomplish more advanced care. [ad: addressed above.]

Related to the clean-up and sanitation issue to prevent spread from body fluids, especially in less developed areas of the world, we need a better way to disinfect large body fluid areas. With materials like fecal material and vomit we have an organic matrix of material with very high chlorine demand that will neutralize bleach and protect the virus particles. This is the same mechanism that make biofilms very bleach resistant. This means that the volume of ordinary bleach necessary to kill all virus in a pool of fecal material can exceed the volume of fecal material thus creating a much larger volume of difficult to handle liquid waste.

A virus that doesn’t seem to survive drying well enough for airborne transmission “could” possibly be deactivated by desiccation. From the physical chemistry many of us all took decades ago, we can note that desiccation is primarily about the “chemical activity” of the water phase, not whether it is a fluid or solid phase material. This means that salts such as NaCl, as saturated brine, which has a lower chemical activity of water, and a huge osmotic pressure “may” inactivate this non-airborne virus and “could” do so very rapidly in a material such as vomit or fecal material without any real chemical reaction.

Ordinary salt, or for even lower water activity coefficient CaCl2, “could” be added as a dry material to the wet fecal material and neutralize the virus, without any of the hazard considerations associated with oxidizers like bleach. Salt is available everywhere in the world at low cost and can be shipped without hazard restrictions or special precautions at much lower cost. It could be safely used by anyone.

However, the above “coulds” and “mays” depend upon whether brine will inactivate Ebola and similar non-airborne virus. As you pointed out, we don’t know that much about deactivation of virus and the differences between airborne and non-airborne virus.

With your contacts in the virus research community at BSL 4 facilities, if it hasn’t been done, you may get someone to test whether this Ebola virus can survive in salt brine. If it is rapidly deactivated, we would have a excellent tool to help contain this virus that is not only available everywhere, it is non-corrosive to human skin and not destructive to cloth. The impact of brine on Ebola would be a low cost experiment relative to its “potential” benefit, if it worked, especially in areas without sanitary systems, autoclaves, biosecure transportation systems, biological incinerators and swimming pool supply stores and Home Depots with their pallet loads of bleach.

Thank you,


PS: I did a quick search on Google Scholar and came up with nothing that appeared relevant about the impact of salt brine on ebola. As an applied scientist/engineer, I look at the pathogen transmission problem as a situation where 99.99…?% of the infectious agents are inactivated or lost or eaten by something that says “dinner” to what we call a pathogen and adding another factor of 10 to 100 to that loss can often shift the situation from an epidemic to a self limiting non-issue (R < 1).

PS2: If ordinary salt does inactive Ebola, cloth saturated with brine and dried could make a fairly effective barrier to direct contamination by an infected person without creating a major disrobing/decontamination risk and a cheap, available hand/body wash.

PS3: I do know that cryptobiotic organisms go to great lengths to protect themselves from dehydration and this isn’t a trivial problem for life to deal with. The ecologies of salt brines are very restrictive with limited biodiversity.

Dallas E. Weaver, Ph.D.
Scientific Hatcheries

Andres writes:

Dear TWIV Team:

Thank you for the wonderful coverage you have been doing on the current Ebola outbreak. I am an avid listener from Costa Rica, and currently starting my PhD in Germany with the Drosten group. I want just to comment on the current reservoir knowledge on Ebola. In the previous TWiVS you all have said that the known or possible reservoir is the bat. This information is based on a paper where they found Filovirus nucleic acid in three different species of fruit bats Hypsignathus monstrosus, Epomops franqueti & Myonycteris torquata. (Leroy EM, Kumulungui B, Pourrut X, et al. Fruit bats as reservoirs of Ebola virus. Nature2005;438:575-576) and it’s one of the only leads as towards which animal might be the actual reservoir. That and that a close cousin of Ebola, Marburg virus, is also found infecting bats and they are the known reservoir of this virus. The problem is that there is no clear information in how bats maintain an enzootic cycle of the virus and how it is transmitted between them, important information to actually be considered a reservoir.

In several other examples of emerging diseases around the world it has been shown that bats constitute the reservoir of ancestral viruses, and that more often than not a secondary host that has closer contact to humans, or that is closer to us phylogenetically, is the host that brings the infectious agent into humans. Examples of this is SARS and the recent MERS CoV, sequences have been found in bats but camels have been found to be a more important host, and closer to humans as well. Ebola is known to infect other wildlife species as well as non human primates, so is it possible that contact with non human primates as bushmeat or illegal trade might as well be the bridging gap between the bats and humans? Contact exists, and also they are closer to us phylogenetically. As you said in past TWiVS this is a social disease and human practices as encroachment into the wild, contact with wildlife, deforestation, and others might be the cause of the spillover. I would like to emphasize that killing bats has not shown to be any good towards disease control, and that it actually be detrimental to controlling the disease as well (examples include Marburg and Rabies). Bats already have a bad reputation, but they are important pieces of the ecosystem being pollinators and seed dispensers. So I just wanted to emphasize that although bats are considered reservoirs, there are other possibilities so we should start by changing human practices if we want to prevent this viral spillovers. I would like to hear your comments on this. Thank you again and keep up the good work!

University of Costa Rica

David writes:

Vincent and friends,

Thanks for your great Ebola coverage. I just want to make a comment on one recurrent meme that bugs me. The CDC has been vilified for letting an Ebola exposed nurse fly after she reported a mildly elevated temperature. Note I didn’t say fever. Fever is usually defined as a temperature outside the normal variation for humans, which is about +/- 2 degrees around the mean of 98.6 degrees Fahrenheit. To be fair, some studies dispute these numbers, but not to a large degree.

To try to be succinct and scientific, consider measuring body temperature in those who are exposed to Ebola as a screening test. If one sets the threshold for the screen low, then most Ebola cases will be discovered at the expense of an overwhelming number of false positives. Setting the bar too high will miss too many Ebola cases while avoiding the majority of false positives. The CDC chose a cut-off of 100.4 degrees, which seems very reasonable to me in my practice as a pulmonary/critical care doctor.

This brings me back to the phrase “low-grade fever”. This seems to me like low-grade pregnancy when a pregnancy test is above average, but within normal limits. It’s a value-laden phrase that implies the desire for fever, or pregnancy, on the part of the speaker, but really translates as normal.

The Ebola infected nurse did not have a fever when she traveled. She later developed one, and was diagnosed with Ebola. About 50% of her fellow travelers had a temperature above 98.6 degrees Fahrenheit, and none of them, so far as we are aware, went on to develop Ebola infection.

Let’s recognize the imperfect nature of this test, and stop bashing the CDC for not quarantining the Ebola exposed with a temperature above average, which would be about 50% of healthcare workers, travelers, hospital staff, taxi drivers, etc. More if this measurement was made repeatedly.

61 degrees F and 28% humidity here at 10 p.m. in lovely Denver, CO. BTW, skip this email if this point has been discussed before.

Best podcast ever,


Paul writes:

links: Legal authority for quarantine and isolation

CDC fact sheet: http://www.cdc.gov/sars/quarantine/qa-isolation.pdf
CDC links to Federal legal authorities: http://www.cdc.gov/sars/legal/index.html
Table of each states applicable laws http://www.ncsl.org/research/health/state-quarantine-and-isolation-statutes.aspx from national conference of state legislators.

As of this writing (9 windless degrees and 68% humidity) the governor of New York has purported to impose a quarantine on health workers returning from helping although it appears from the above referenced chart, that is the province of the local board of health and health officer (who were not consulted http://www.nytimes.com/2014/10/25/nyregion/new-york-ebola-case-craig-spencer.html?hp&action=click&pgtype=Homepage&version=HpHeadline&module=a-lede-package-region&region=top-news&WT.nav=top-news )

As this situation continues and people flail around for solutions, it is important to remember that isolation and quarantine constitute deprivation of fundamental constitutional rights…it is imprisonment…which requires more than an enabling statute but genuine due process and equal protection.

Similarly, the right to travel is a fundamental human right that must weigh in the balance in considering policy interventions.

By the time the next ebola episode airs, the headline above will be old news, but I suspect the issue will be of growing importance.

Juan writes:

HI, I can see the merits of both arguments on whether or not execute a flight ban from Ebola affected countries. While this would contain the epidemic to a certain degree, we should remember that this is a social problem, and the problem with the ban is who will establish such a ban? I’m afraid that if the flight ban is established unilaterally by the ‘West’, people in those (affected) countries will see it as an imperialist action (Remember polio in Nigeria) and therefore worsen the little cooperation with any other countries. If such a ban was to come into effect it would have to come from those countries which seems unlikely.

Curt writes:

Hi, TWiV team!

Our EMS agency provided ‘Ebola Gurney’ came in. Frankly, it seems like more trouble than it’s worth from an emergency scene, but it might work pretty good for transferring between hospitals. It gives people a sense of security, though, so that’s got to be worth something.

Thanks for your hard work!

Charles writes:

Oh, no, not another Ebola article!
Hi Drs Twiv,

The Atlantic has put up an article titled, 21 Days: A biological warfare expert’s warning against false comfort in Ebola messaging. I imagine you’ve probably seen it already, but i thought i’d bring it to your attention so your devout listeners can hear your opinions on it.


Keep up the good work!

Anne writes:
Hello, TWiV Team,

Wondering if you would care to comment on this article, which showed up in The Atlantic recently.


David writes:

Dear TWIV team,

Greetings again from Nicaragua. I have been listening with great interest to your discussions in the last quarter year about the Ebola outbreak and its many aspects. Ever since I left for Africa in 2007, I was fascinated by ebola because of its grotesque features – it is highly lethal and frankly, of all viruses out there, I guess it would be the one that leads to the most gruesome death, with internal and external bleedings, fever, vomiting and diarrhea. Not a nice way to go. This interest was rekindled when I took Dr Racaniello’s virology courses on coursera.

The outbreak that holds the world in its grip now is in my very humble opinion (as a microbiology hobbyist/lifelong learner) rightly a reason for great worry. The outbreak has reached Mali, and it is only a matter of time before Burkina Faso will join the group of unfortunate nations in the Horn of Africa. Developing countries are no match for a premier league killer virus, they can hardly handle the every day rhythm of infections that claim millions of lives on a yearly basis. Having my current residence in Nicaragua, I am quite sure that if the virus would cross the border, it would be just as lethal as in Africa. Apart from the opulent West (say: the US, Canada, Europe, Down Under and probably Japan), there will be hardly any resistance to further spreading.

Correct information is key, and I finally make it to the question that has been puzzling me for the last weeks, and that does not seem to raise any critical questions so far: how can it be that the scientific community claims that Ebola patients on average only infect 1 or 2 persons? Taken on face value, this appears to be humbug. If the virus would be so hard to transmit, how is it possible that patients in prepared hospitals in Spain and Dallas infect nurses? Are these nurses extremely negligent, or are they willingly taking in bodily fluids from the infected? Of course not: they know they are dealing with a dangerous virus, and most people cling to life with everything they have, but even a small sidestep from precautions is enough to get them infected apparently. These are hospitals that were beforehand considered to be completely prepared to deal with the virus, and even then the average rate of infections is met. How then would an infected patient not cause more transmission when he is at work or in a bus?

The only explanation I can come up with is that the transmission estimates are based on the previous outbreaks that took place in small villages of 100 people, where most got infected and the virus could not spread due to containment. And that in the absence of any new scientifically supported figure, the old estimate gets cited over and over again, thus also avoiding panic. If this were the case, I don’t think it would be a consequence of bad intentions to keep the public uninformed about the real dangers, but rather a scientific lag.

I would really love to hear your thoughts on this. While this may be a delicate topic and it would be impossible to forward a different (and more realistic?) transmission rate, I believe that I am not the only one who is doubting the relative difficulty in passing on Ebola, and it is always better to have an open discussion about it than to leave it to wild speculation. There is of course the very real probability that I lack the needed microbiological/epidemiological insight and my doubts are to be blamed on ignorance, but even then I would love to be enlightened.

I greet you from Jinotepe, 30 degrees Celsius at noon, humidity of just 62 % and a hardly noticeable breeze of 11km/h.

Yours sincerely,


Simon writes:

Hello ConTwivstadors!

In episode 307 someone brought up the idea that one could browse through genomic sequence data in search of hosts for viruses (specifically about Ebola if memory serves) and Alan responded by saying that this would be too expensive because of the needle-in-a-haystack scenario where you are looking for a relatively short sequence of a couple kbs in trillions upon trillions of kbs of data.

While I will certainly not question the infinite wisdom of this Western Massachusetts gentleman, I would like to modify the question of the asker of said episode and ask the following:

Would this also be true of retroviruses? If retroviruses are the result of a retrotransposon gaining a few genes for structural proteins, this should imply that for every retrovirus there is a “causal retrotransposon”, if you will, and those tend to exist in quite large numbers in non-coding regions their host genomes and that should mean that you could add a couple of extra needles to Alan’s needle-in-a-haystack analogy. Would this be a proposition worthy of testing? Has it already been tested? If so, by who and on which virus because I would like to read that.

The very kindest of regards,

Ps. The weather in Kiruna, 1300 kilometers north of Stockholm, Sweden, is as you would expect as snowy as a snowglobe in an earthquake. Nothing else to report. Checking out!

Jacob writes:

Hi all,

I was going to write in letting you know about a special issue of Virology journal about giant viruses as a pick of the week, but then I noticed the Editor, so I’ll let him talk about it. I had to laugh when I saw this paper title “Origin of giant viruses from smaller DNA viruses not from a fourth domain of cellular life” and I knew already who the author was going to be purely from listening to TWiV.

Bit of a nit-pick while I’m here. Back in TWiV 301 your guest Curtis Suttle talked about the carbon turnover attributable to viruses in the oceans being about 150 gigatons per year. Gigaton is a measurement of explosive force of nuclear bombs, not mass. The correct unit should be petagram (1×1015 grams), which is equivalent to a billion tons. I know y’all don’t use our fancy Metric System but I see this one rather often and it annoys me (sorry, I’m a measurement scientist as well as a molecular biologist). I’ve also attached a nice picture I saw on Reddit a while back regarding the two measurement systems (Imperial and Metric). [Coarse language alert]

It wouldn’t be a TWiV email at the moment without some mention of Ebola Virus, so I’ll just leave this here. Last weekend I was walking past a group of teenagers waiting for food at a takeaway place. I didn’t hear what the conversation was about, but one sentence caught my attention: “And she was wearing, like, a full on Ebola mask”. I’m still not sure what they were actually talking about, or what an “Ebola mask” would be specifically, but it was nice/strange to hear ‘normal’ people talking casually about it.

Weather in Sydney is sunny and 23°C (296 Kelvin [not degrees Kelvin, just Kelvin])

p.s. You should do an all email episode at some stage J

p.p.s If you are reading this as part of an all email episode (thank you) replace the above with “You should do another all email episode at some stage”

Todd writes:

Greetings masters of the TWiViverse!

I just recently started listening to your podcast after having heard about it a couple years ago (better late than never!). I know you are all probably sick to death of talking about Ebola, but I was hoping you would indulge me.

I recently learned (via Orac at Respectful Insolence and Pepijn Van Erp at his blog) that Homeopaths without Borders has finally gotten some of their people into Liberia to “help”. This has me a bit concerned.

I was wondering if you might discuss a little bit about the potential for these individuals to become infected (are they properly trained in PPE use?) and, more frightening, the likelihood of their carrying the disease back to their home countries. In particular, with homeopathy as popular as it is in India, does their involvement in Liberia mean that we will be seeing an outbreak of Ebola in India in the near future?

Love the podcast and am starting to work my way through the backlog!

Todd W.

Paul writes:


Some professors, postdocs, PhD-students are more successful at science than others. But why?

Yegor writes:

Hello Vincent,

It was great meeting you at the Salk Symposium yesterday.

Here’s the link to the “podcast” that I mentioned: http://www.dancarlin.com/hardcore-history-series/
You’d be hard-pressed to call it a podcast, since these are 3-4 hr episodes that come out every month or two, but they are excellent. The host is a fan of history and he has the amazing ability to keep you engaged and interested to these long lectures on a variety of subjects. I got hooked on this and now am binge-listening to all the past episodes (intermixing them with twiv, of course).

Yegor Voronin, PhD
Senior Science Officer
Global HIV Vaccine Enterprise

Amanda writes:

Greetings all,

Been listening to TWiX for quite a while now, and I love them. Although, I’m a bit behind since it’s often hard to download on our limited cellular network here in Papua New Guinea. So if someone else has already picked these articles, I apologize for the repeat.

Here’s a short summary of the ‘scary’ chemicals in vaccines and how they are not so scary after all when you do some basic math:

An interactive map showing the damage anti-vaxxers have done:

And finally, here’s a story about why the minds of anti-vaxxers are so hard to change, even in the face of facts or emotional appeal. So the links above, though seemingly powerful to those of us who support vaccines, may not be so helpful after all – but what else can we do but try?: http://www.newyorker.com/science/maria-konnikova/i-dont-want-to-be-right

It’s 23 degrees Celsius in Goroka PNG, looking like torrential rain will be showing up in a few hours.


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