Ana Fernandez-Sesma writes:

Hi Vincent. Today we are having the first group of PhD candidates visiting and half of them heard about us in TWIV! Thanks for doing such a great job!

John writes:

Quoted in TWiV 318, Ron Fouchier predicted a lab acquired infection rate of less than once per million years.

Anybody who takes that seriously should read Richard Feynman’s appendix to the Rogers Commission report on the loss of the space

shuttle Challenger.

NASA managers claimed a 1 in 100,000 chance of failure per shuttle launch.  Feynman observed that the historic failure rate of solid

rocket motors, over thousands of launches, was 1 in 25 but improving. Over its lifetime the shuttle had a 1 in 63 failure rate.

Reliability of complex systems is estimated by extrapolation.  It’s engineering, not math.

I used to work on development of a big, complicated medical printer. We ran thousands and thousands of sheets through it and every time it failed, somebody recorded the details of the failure. The printer was only as reliable as experience proved.

With good statistics you can see where the design flaws are.  You fix the worst problem and the second-worst problem gets a promotion.  A plot of failure rate vs. time shows a decreasing trend.  The right end of that curve is your current reliability.

 Labs full of humans are complicated systems and should also be judged by experience.

When smallpox was studied more often, workers were infected.  A decade ago there were cases of lab-acquired tularemia.  Just 15 minutes earlier in episode 318 Ebola was handled at BSL-2 instead of BSL-4.

Each incident is less serious than the previous.  That’s good.

 On the other hand, many lab-acquired infections must go unnoticed or unreported.  Most vial mishandling incidents don’t make the New York Times.

I think we can say based on experience that the chance of lab-acquired infection at BSL-3 or BSL-4 is greater than one in a million per year.

If there is a proof to the contrary, I am prepared with this oft-cited statement by computer scientist Donald Knuth when he sent a new program to a colleague:

“Beware of bugs in the above code; I have only proved it correct, not tried it.”


P.S. It is -16 C in the suburbs of Boston, headed for -20.



TWiV 318 at 41:40: “From this analysis the conservative estimate is that when, in the Erasmus medical center facility to which ten persons have access, research is performed on transmission of influenza viruses via respiratory droplets or aerosols between ferrets, one laboratory acquired infection would be expected to occur less frequently than once every one million years.”

 Feynman appendix to Rogers Commission report:

 Recommended reading:

 _Catastrophe: Risk and Response_ by Richard Posner:

Anthony writes:

I’m attaching a spreadsheet from the State of NJ for rabies statistics.  There are many cases in raccoons for the year 2013.  Even looking at a 10 yr period, there are extremely few in opossums.  The “Virginia” opossum is very common in NJ and may be found in the same environment as the raccoon — my street in Jersey City,  for instance.

Curiously similar is that for the bat-borne virus outbreaks in Australia, those stricken were people and other placental mammals –not the native marsupials. (“During the initial epi study of Hendra virus, limited number of marsupials were surveyed, but they were all -ve for Hendra.” Prof. Linfa (Lin-Fa) Wang, PhD FTSE)

It appears that there’s another connection between marsupials and bats.  Both have lower body temperatures than other mammals — marsupials at all times and bats when not flying.

As noted in one of your podcasts, bats are difficult model animals. That’s not so for opossums.  Road kills are readily available.  I wonder if like bats they might carry viruses, but be asymptomatic?


Gerson writes:

Dear Sir,

There are certain viral diseases which are said to have no cure. One of these is Hepatitis B.

Since there is no cure for Hepatitis B , if the anti viral medicines cannot eliminate the virus how can they reduce the viral load? What do these anti viral medicines actually do to the virus?

Anthony writes:

Virus Scare at CDC Points to More Problems With Lab Animals

Was this /  will this be covered at TWIV?

Thank you,


Mikhail writes:

Hello dear TWiV team: Vincent, Alan, Dickson, Rich, Kathy, and all folks that have been or will have been on the show!

First, I would like to express my sincere appreciation for your enormous undertaking in enlightening public about microbiology in general and viruses in particular. I recently started to listen to TWiV and completed 112 episodes in about three months. Your podcasts make my morning runs not only physically, but also mentally healthy. I have recently set my personal record for marathon while listening to episodes discussing ebolavirus (I will get to that later). Also, half an hour commute is now filled with knowledge rather than the boredom.

I got my PhD in virology in Russia studying tick-borne encephalitis, and then worked on yellow fever virulence and attenuation and murine CMV role in cardiovascular disease in Louisiana State University Health Sciences Center in Shreveport. This year, I started to teach full time in Lakeland Community College near Cleveland, OH. My colleague and I recently were chosen to present about Zaire ebolavirus outbreak, and your podcasts were immensely useful in preparation for this venue. Our presentation had a great reception, and I was able to give detailed answers to the questions that you have already discussed on the show (e.g., vaccines). So thanks a bunch for your help!

In the episode 112 you discussed the education gaps in US college students. As a community college teacher, I can testify that the lack of basic natural science education in high school takes its toll at the college level. Coming from quite a different education system, I would suggest that having mandatory basic courses in chemistry, physics, and biology that are focused on the foundations of these disciplines rather than on the details will be of a great benefit for the future students. Science is hard, and I suspect that this plays a role in the fact that high school students refrain from taking science courses leaving them for college. And college science is even harder.

Thank you for taking time to read my e-mail. You are doing an excellent job and a great service.

Best regards,


Mikhail “Mike” Khoretonenko, PhD

Assistant Professor

Department of Biology

Lakeland Community College

Joakim writes:


Firstly, thank you for this amazing show and a big shout out to Jesper who presented me to it.

I started listening to podcasts just this spring, and it took me quite a while before finding some that were worth listening to (obviously TWIX included). In the end there are almost only two “groups” of casts that I really long for, and except for you guys it’s also the history/political podcast of Dan Carlin (i.e. Hardcore History and Common Sense). So imagine my surprise when Common Sense happened to go in to the world of TWIE (This Week in Ebola virus). The episode discusses the political play in regards of the west African ebola outbreak. If not as correct as TWIE, it still asked some money-questions in regards to possibly pandemic virus outbreaks in comparison to other state related economical posts.

Please never stop the awesome work you are doing!

Regards, Joakim

Senior QA Engineer

Stockholm, Sweden

PS November in Stockholm, Sweden has been the grayest and dullest possible with ~5h of sun and between 3°C and 10°C.

Todd writes:

Greetings, TWiVers!

While working my way through back episodes, a comment in TWiV #11 about a rat catcher who never used gloves or other precautions for 25 years got me thinking about sparrow viruses. The common house sparrow in the U.S. is an invasive species, and I’ve read about people trapping them as a way to try to help native birds reclaim their territory. Are there any viruses commonly found in sparrows that can cause illnesses in humans? How might they be transmitted?

I’d love to hear your insights on this, and hope my question gives you an opportunity to talk about zoonotic illnesses.


Todd W.

Jenn writes:

Hello TWIV team,

I’m a PhD candidate at the University of Georgia specializing in wildlife disease. My dissertation explores the epidemiology of a novel Orthomyxovirus in sea ducks. I started listening to your podcast several months back as I prepared for my qualifying exams. I enjoy them tremendously and often listen during my lengthy commute. I’m excited that you covered several wildlife disease issues recently (sea otters and sea stars). It’s a great field of study, and I was glad to see it acknowledged in a favorite venue. I have one small comment regarding episode 315 where you discuss the sea star wasting disease. Dr. Spindler was very excited about the use of the word “extirpate.” The definition you referred to is the common language definition  of “root out and destroy completely.” In the field of wildlife management, the word “extirpate” has an alternate but very important meaning. It means localized extinction. True extinction is the complete die out of a species; extirpation is the dying out of a population or species within one location. If you reread the sentence with that definition, it has greater significance than simply a linguistic flare. I don’t mean to be too critical. It’s not something that a specialist in another field is likely to come across, but I thought the information would add clarity. Keep up the great work!

It is currently 49 F in Athens. The weather channel tells me it’s partly cloudy, but I wouldn’t know. I’m a graduate student. I haven’t seen the sun in months…


Jenn Ballard, DVM

Wildlife Disease Diagnostician/Doctoral Candidate

Southeastern Cooperative Wildlife Disease Study

The University of Georgia

Aline writes:

Hi everybody! I had weird case at my work this month. A patient, who lives at a rural area, during a week drank water from a water reservoir where a bat was found dead ( bat juice?) Well, at the moment that this case was introduced to me, I was in doubt to install rabies post-exposure prophylaxis, since no oral transmission was described, but…rabies kills, vaccines don’t ( I suppose). What do you TWiVbolans think about that?? Is there a chance to transmit? There is an oral vaccination in fox isn’t there?

PS: I work with zoonotic surveillance in the south of Brazil. I’m waiting for the results of bat rabies tests.

Aline Campos, MV


Vigilância dos Riscos e Agravos Ambientais Biológicos                                            

Vigilância Ambiental em Saúde                                                   

Nucleo Regional de Vigilância em Saúde – 9ª CRS                                                        

Secretaria de Estado da Saúde-Rio Grande do Sul

Robin writes:

Current wet bulb temperatures are hard to come by. This has the current wet bulb temperatures for all of Florida, including Gainesville.

Neva writes:


Inventive but I won’t be wearing these. Not as cool as knitted or beaded virus models.


Neva from Buda

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Basel writes:

Dear Dr. Racaniello,

I would like to share this as pick of the week. I hope it gets picked before March 4, 2015.

This is the annual FDA advisory meeting in which the FDA listens to public, scientists, and any interested parties in discussing and making recommendations on the selection of strains to be included in the flu vaccine for that year.

The next one will be held on March 4, 2015 from 8:30am-3:30pm for the 2015-2016 influenza season.

As per FDA website, any interested person may present data, information, or views, orally or in writing, on issues pending before the committee. Meeting details including agenda, location, webcast info…etc are available on the website.

I hope TWIV listeners find this useful, and pass it along to interested others.

Kind Regards,


Basel T. Assaf, BVSc, PhD, DACVP

Investigative Pathologist, Staff Scientist


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2 comments on “TWiV 319 letters

  1. His latest quote on the risk assesments:
    Fouchier questioned whether the government’s current effort to weight the benefits and risks of this kind of research is going to provide any new insights that haven’t already been discussed over the last three years since the debate over his experiments first began.
    “I think that the quantitative risk and benefit analysis is going to be close to impossible,” Fouchier told NPR. “Whatever the numbers are they come up with, in the end it will still be a judgment call by someone, somewhere.”.
    The European Commission is also evaluating the risk of synthetic biology again, contributions still welcome: