Ted writes:

Hello Vincent I hope all is well.

First wanted to thank you for several months ago introducing me to your TWIV broadcast. They are very informative and a good listen especially now with the Ebola situation.
Years ago (before finding your work), hearing there was a large Ebola outbreak and then seeing an interview with a Doctor like I saw on Fox News today, would have made me call in sick and start stockpiling food, water, guns, Hazmat suits and prepping for the end. But after listening to your class on podcast then hearing your discussions on TWIV I feel I have gained some knowledge on the subject and I no longer panic. So I thank you and everyone on TWIV for that, it’s a beautiful thing.

What made me send this to you was as I said above this morning I listened to an interview with a Dr. Jorge Rodriquez on Fox News. He said that the virus is in all these people and its constantly mutating. He said the virus is like a string of red beads inside these people and all it takes is for one red bead to turn blue and then poof it becomes airborne. Like I said five years ago the Doctor saying this would have put me in panic mode, after TWIV it’s rather comical. If it is that simple of a process how come in other Ebola outbreaks it never happened. If its that simple why doesn’t the Dengue Fever virus (which the virus is in far more people than this current Ebola) say hey guys instead of having to wait for and travel with a vector why don’t we just make one of those red beads turn blue and we can go airborne and spread faster. I think you all need to get Dr. Jorge Rodriquez on your TWIV broadcast and have him explain to you all just how simple it is for a virus to mutate and turn that one red bead to blue, and let’s have it live on Fox News.

Keep up the good work you all are the best at what you do.

Del writes:

Dear TWIV team,
One of the letters from your recent episode “the sky is falling” seemed to take you to task for not being clinicians and therefore not really understanding the nefarious intentions of Ebola. As a clinician myself I simply want to counter that impression by commending you for how clinically thoughtful and relevant your discussions are. TWIV is, after all, about viruses–the kind that make you sick! You seem to me to be meticulous about NOT making clinical statements about which you are unsure, but even that doesn’t seem to happen often because you seem to do your homework before the show. We fight a constant battle against misinformation in this media-driven world, and you are fighting the good fight.

As an example of this balancing wire we walk with the media, and please forgive me Kathy for using your institution as an example, several years ago we were having an apparent increase in invasive streptococcal infections in our state. I was personally caring for two severe cases in one of our hospitals in Saginaw, Michigan at the time. When I returned home that evening I walked in to see a press conference on the news from the University of Michigan Hospitals. The head of the ID department and the head of the hospital system were answering questions from the media about the one case of ‘flesh-eating infection’ they were currently treating in their ICU. That was the day I realized that it is all about marketing, and I am not a marketer.

I commend you for the invaluable contribution you are making to science and to medicine, and I am evangelizing your podcasts among my colleagues.

Del DeHart MD
Associate Professor of Medicine
Michigan State University

Robin writes:

How likely is Ebola to transmit by aerosol? Slightly more likely than for pigs to fly. And like bats, pigs are mammals.

The Walrus and The Carpenter
“The time has come,” the Walrus said,
“To talk of many things:
Of shoes–and ships–and sealing-wax–
Of cabbages–and kings–
And why the sea is boiling hot–
And whether pigs have wings.”

Robin writes:


Stephen writes:

Kudos to Kathy Spindler for nailing the nature of a listener e-mail (and by extension several other recent e-mails) about the ebola epidemic. TWiV should turn its troll detector up to 11. If there are important points you all would like to make, they can be made without repeating a list of what-if and how-do-you-know questions that repeat incorrect or misleading ideas.

As Vincent said repeatedly, we and policy makers have to rely on evidence. What’s the alternative?

Mary writes:

Greetings TWiV Team,

Weather today is in upper 80s and sunny in Colorado.

Thank you for sharing your expertise so that many like myself can better understand the world of virology. I became a TWiV listener after taking Virology I and II classes online.

The CDC and WHO websites for Ebola statistics has been silent the month of September, today is the 17th, about the number of cases and deaths in western Africa. The approach is now focused on how to recognize the symptoms, prepare and protect. Leads me to believe that the probability that it will “jump the continent” of Africa is increasing to the point that this event is now probable. These agencies do not respond to inquiries. Would you recommend viable sources?

Thank you,


Dallas writes:


You can view aerosols from a physical chemistry viewpoint. A small liquid particle containing virus, soluble organic material and salts will rapidly evaporate in any air at less than 100% relative humidity. This will result in rapid osmotic pressure change, which could be very rough on virus particles not designed for desiccation. At 100% RH, the particle with the salts will grow in size and fall out of the air column. In either case, epidemiological evidence would indicate non-aerosol transmission.

Love the podcast,

PS: we play these osmotic pressure games for biosecurity in some fish/shrimp hatcheries by using saturated salt brine to kill most aquatic pathogens of all types on surfaces and equipment. Very effective against biofilms that can effectively be desiccated with brine in seconds, while being easy on the staff’s hands (especially relevant in some developing country situations).

Dallas E. Weaver, Ph.D.
Scientific Hatcheries

Yegor writes:

Dear Twivers,

You discuss at length the very unlikely possibilities of Ebola becoming transmissible via airborne route or by mosquitos, but have you talked about the more real possibility that it will become attenuated in the course of the current epidemic? Perhaps I missed it. If the virus becomes less pathogenic while preserving the ability to transmit between humans, that may lead to serious problems. In the worst case scenario, the virus may even become endemic. I think attenuation of the myxoma virus in Australian rabbits is one example of this happening – the virus was extremely pathogenic at first, but now it’s relatively mild (although I’m not sure how much of the change in pathogenicity is due to virus attenuation and how much is due to selection on the host, probably both happened).

At the moment, people become infectious when they already have very serious symptoms and one can hope that those symptoms are required for transmission and a less pathogenic virus will simply become non-transmissible. But maybe not? I would imagine that at early stages of the disease (or during a mild disease) sexual contact may provide the necessary contact with bodily fluids and enable transmission. Are there known cases of Ebola being sexually transmitted?

Thanks for your excellent coverage of the Ebola epidemic,

Yegor Voronin, PhD
Senior Science Officer
Global HIV Vaccine Enterprise

Jim writes:


Wanted to comment on Dallas’s letter. He is predicting the future and predicting doom. The Cambridge Working Group is also predicting a future of doom. Both sides seem to feel the other side is incapable of understanding what is really going on.

Nate Silver in his book

The Signal and the Noise: Why So Many Predictions Fail but Some Don’t

describes situations in which data has to be sifted to come to a conclusion on how to bet. If I understand him correctly it helps to assign a probability to the prediction. This is a measure of how strong the data is. For example, would the Cambridge Working Group say there was a 10% chance that their predictions would come true or would it be closer to 90%? Likewise would those who favor Dallas’ view of the system being overrun by bureaucrats with unreasonable control see this as 95% likely? As an outsider I would give each side a 50% chance of being right. Would that the data were stronger. For now, each side has unsubstantiated, anecdotal data and not much else IMHO.

Both sides address this issue with great conviction. As I hear it, the data is puny on both sides. So far I have not heard anything convincing on either side. Cheering for either side seems to miss the point that the data is poor.

As Yogi Berra is reported to have said, “Predictions are difficult especially about the future.”

I love all things Twiv, Twim, Twip, and Urban ag. I appreciate your tolerance for listener views which are different or wrong.

Louie writes:

Be a little more precise when you talk about transmissions. Ebola is not transmitted by the “airborne route”. That would be like TB and measles by particles suspended for prolonged periods in air. Aerosol is a bit less precise–when I cough, I can produce an aerosol of what I call the “big chunks” that can land in your eye or on your oral or upper airway mucosa and could cause infection. Airborne requires relatively sophisticated respirators, like PAPRs etc. and sophisticated isolation rooms with negative air pressure and specific flow patterns. See the CDC page on transmission-based precautions. The “big chunks” require contact and droplet precautions, i.e. face shields and surgical masks, or N95 masks, at most and infection is not by the airborne route. It is an important distinction.

Greg writes:


In listening to the letters about Ebola that were discussed in episode 302, it seems that more than one of the letter-writers had concerns about *airborne* transmission of Ebola, yet used the non-equivalent term “aerosol* transmission.

Although Kathy provided a very clear definition of aerosol transmission, in terms of particle size and the requirement that they be inhaled, I think it might help your listeners to explicitly distinguish this form of transmission from more generic airborne transmission.

Here’s how I put it together.

There are multiple potential routes for *airborne* transmission. One is aerosols. Another, as a letter writer mentioned, is coughing up blood. A third, technically, is throwing a beaker of infected blood at someone.

The key difference is the epidemiology of spread, i.e. the R-zero. As Vincent said, aerosol transmission can infect an entire subway car full of people after a sneeze. The non-aerosol airborne transmission that results from coughing blood or throwing a beaker would be expected to infect only people directly in the line of fire.

Therefore, as far as we know, Ebola is transmitted between humans only by body fluids and tissue. This means that *airborne* transmission can occur in circumstances like coughing body fluids or tissue, but this is the exception. There is no known evidence that *aerosol* transmission has ever occurred between humans.

I hope this helps.

Best regards to all the TWIV team,

Basel writes:

Dear mutual vaccination proponents,

I’d like to share with you a story that happened to me this past weekend that I thought is worth sharing.
As first time expecting parents, my wife and I took a birthing class among many other parenting-naive parents-to-be.

The birthing instructors gave a fairly balanced discussion on the pros and cons of many topics such as epidural vs. non-medicated birth, vaginal vs. cesarean delivery…etc, even what weirdly to do with the placenta after birth (take it home, dry it and drink it…). What ticked me off the most was that when it came to vaccinating your newborn, they stepped back claiming that it’s a “parenting decision” we need to discuss at home. I thought the least they could have done is providing and discussing the pros and cons of vaccination (if there are any cons for that matter).

I didn’t like that. All attendees were new expectant parents and the main reason they were in this class is to learn, and what’s more important than discussing this topic especially in Portland, Oregon, our fair city (as Click and Clack, the Tappit brothers say) with the surge in Measles cases.

I thought if there is any class to discuss this topic is has to be birthing classes and newborn care classes. We’re taking a newborn care class in couple of weeks in July and I hope I don’t encounter such unpleasant scenario.


Basel T. Assaf, BVSc, PhD, Diplomate ACVP
Investigative Pathologist; Staff Scientist III
Division of Pathobiology and Immunology
Oregon National Primate Research Center
Oregon Health and Science University

Christoph writes:

Dear TWIVers,

I am a long time listener and have patiently been waiting to contribute my five cents, so here it is:

In TWIV 289 Vincent stated that he does not believe anything eats viruses. I have to disagree. Check out this contribution from Juan González and my PI Curtis Suttle:
Gonzalez, J. M., and C. A. Suttle. “Grazing by marine nanoflagellates on viruses and virus-sized particles: ingestion and digestion.” Marine Ecology Progress Series MESEDT, 94.1 (1993). (http://www.int-res.com/articles/meps/94/m094p001.pdf)

Turns out viruses make up a small, but significant proportion of a balanced phagotrophic nanoflagellate diet. Also bear in mind that this study was pre-Megavirales, I am sure a Mimivirus or a large Phycodnavirus makes a welcome meal for those little flagellates (and they are abundan: Hingamp, P., et al. (2013). “Exploring nucleo-cytoplasmic large DNA viruses in Tara Oceans microbial metagenomes.” The ISME journal. (http://www.nature.com/ismej/journal/v7/n9/full/ismej201359a.html)) !


PS: The weather in Vancouver BC is currently 18°C (64°F), sunny with a humidity of 24% and no wind.

Richard writes:

Dear Twivers,

I refer to TWIV 281 “The Salk legacy with Peter L. Salk” and I would like to offer a somewhat different interpretation of Jonas Salk’s famous comment about patents and the sun. In 2002, I was asked by the Rockefeller Foundation to examine the extent to which patents (Intellectual Property – IP) limit access to important health technologies for the poor in developing countries. Our study led to the conclusion that achieving access to these technologies requires attention to R&D, establishing high quality manufacturing, preparation of domestic and international markets, management of IP, and establishment and implementation of high quality regulatory systems to ensure safety and efficacy. Through a number of detailed case studies, we also concluded that while IP management is one of these requirements, it is usually not the most important and is often of little importance. However, when it is important, it is very important. Further, the analysis led to a counter-intuitive conclusion. IP is really important when regulatory requirements raise the cost of development to very high levels, for instance, >$100 million. Under those conditions, no company will invest the required funds without IP protection. Thus, the granting of IP ownership is one means to help raise the funds necessary to ensure safe and effective products. This analysis led us to have a somewhat different perspective about the “patenting the sun” comment in the light of the subsequent Cutter incident.

TWIV is proving to be an extraordinary means for airing important topics that affect a spectrum of the population from parents deciding whether or not to immunize their children to companies deciding whether or not to develop a vaccine. You are doing a wonderful job.

All the best,


Jon writes:

i’m scared of science – trust me i’m a scientist
i’m scared of being treated like cattle – scientists use the term “herd immunity”

i’m a scientist but don’t trust myself so will have a blind experiment, better make it double blind, that is how much i don’t trust myself, and wait for peers to replicate it – but trust me, I’m a scientist.
i’m a scientist working for the arms industry
i’m a scientist lobbying for government patronage
i’m a scientist with a lucrative patent.
people who are not trained to think scientifically are still problem solvers and very intelligent, so they will solve their problems without scientific training.
my child is healthy – why invade them with a vaccine and subject them to a needle? – trust me i’m a doctor?
you cannot fake science, but you can fake scientific arguments. lay people know this.
scientific training is a matter of social policy and education systems that 90% of the population can be intelligent and productive members of society with highly effective problem solving skills yet unable to evaluate the specialised language of science and then yet the more specialised language of medicine.
you cannot have specialism without the trust of those who are not specialised.
you cannot hide behind science as being pure and altruistic when it is sponsored by invested interest. you cannot raise your hand and say “trust me, i am the good scientist and not the bad one”
you cannot bridge the gap of science versus not science by media and communication skills.
you either are scientific or are not
you either have a population educated in science or you opt for specialism.
i love your podcasts for being better than the rest in objectivity and prolonged debate, with both humor and humility, diligence and controversy.
Own your own frustration at being specialised, keep communicating!
but do not express frustration at people who are scared of you – they have the same brain size as you, and you have the same emotions as the people who are scared of your specialised knowledge.
Mistrust of science is not a failing of those who mistrust and not a sign of ignorance – just normal people without scientific training needing to engage with information they are not educated to process.
Problem solving behaviour is a problem in itself and not necessarily a virtue, yet scientists, environmentalists and health workers are often the last to know that their need to solve the problems is a need, an emotion.
Hysterical people find it hard to hide their behaviour but obsessive people can hide their emotional need of safety through problem-solving by specialism, procedure, productivity, rationalism etc.
Is there such a thing as too much objectivity?
Is there such as thing as too much biodiversity?
Is there such a thing as too much intelligence?
Is there something that is not the environment?
Is there something that is not nature?

My points is that science, environmentalism and medicine is clothing itself with belief structures:
environmentalists vs sceptics
doctors vs the anti-vaccine lobby
darwinism vs the religious right wing
giving the climate a control mechanism yet expressing the need for nature to be free and wild.
you are an ivory tower as scientists, you will feel loneliness and isolation in your knowledge as scientists, you will have exaggerated emotional perceptions of control and solution. You will have incredible self-imposed expectations to solve problems and express frustration towards those who don’t share your insight.
Please keep trying to communicate, you are doing a fantastic job.
Don’t get frustrated at people who are scared, it doesn’t work!
Most people have the same brain size and are also trying to problem-solve. But own the self interest and betrayal of your colleagues when science has led us wrong and into danger. Trust is a two-way process where science has proved untrustworthy.
Scientifically humans at one point thought the most efficient way to dispose of each other was by gas ovens and use their waste products to make pills and soap.
Intelligence is what you make it through emotion and is very dangerous without.
Once again, please don’t feel discouraged, despite my gloomy email, thanks again for your often startling and informative efforts.
(my problem-solving need was to respond to your stimulating podcasts and receive some feedback to validate my intellectual process, but am feeling well guilty of writing such a long email to join up and solve everyone’s problems)
best regards jon

Nicole writes:

Dear TWIV Crew,

In case you haven’t seen this:

June 9, 2014
Antivaccine Movement Slammed By Daily Sow; ID Doctors, Pediatricians Happy

In HIV and ID Observations, Dr. Paul Sax shares an antivaccine-movement video that makes him very happy.

The antivaccine crowd gets a pretty good drubbing from The Daily Show. Dr. Paul Sax would feel bad for them — if he weren’t an infectious diseases specialist married to a pediatrician. See more in his HIV and ID Observations blog.

I can’t say enough good things about your podcast.

Dee writes:

Hello TWiViMPs
(Virology, Microbiology, Parasitism, as I listen to all three).

Long time listener, but never thought I’d ever write in as I am not in your field(s). My science education is limited to high school biology, and I generally don’t understand anything when you all get super-technical, but I pick up on general themes and really enjoy the conversational learning. Having listened to you guys for this long, I often think I would be a good lab geek. I currently help folks with their technology (mainly a computer geek), and in my past life worked in the music business getting records on the radio (known as record promotion).

In addition to the many tech podcasts I listen to daily, I also listen to a variety of non-tech ones as well, including yours. I was turned onto TWIV from Futures in Biotech, then TWIP and TWIM, although I am a year or two behind on all three! I was disappointed that I missed you in Denver last year because I’m so far behind.

One podcast I listen to is This Week In Startups (known as TWiST) with Jason Calacanis, which discusses tech startups and helps young entrepreneurs with theirs.

On a couple episodes I’ve heard your frustration of papers published behind pay walls. On the Feb 11, 2014 of TWIST, Richard Price of Academia.edu, talks about this issue and I thought it may be of interest to you: http://thisweekinstartups.com/academia-edu-publish-tenure-science-cures/

Here is the episode recap:

You probably know about this already but I thought I’d do so as well just in case.

Thank you for all your time and efforts in putting all three podcasts together.

Basel writes:

My pick of the week is fully functional microscope built from Lego parts.

This microscope concept is submitted to Lego, and upon receiving enough votes Lego will manufacture the kit and sell it in stores so that kids and adults alike can build their own microscopes.

So I’m hoping that this pick gets the TWIV pump and people vote for it.

Here is the link from Lego for voting:

Thank you.

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