TWiV 210

Jamie writes:

Greetings Vincent, and TWIV adventurers !

I’m a 28 [year] old Medical biller, who has sort of floated thru life not really knowing where my passions lay.

I’m not even sure how I came along TWIV, TWIP and TWIM, to be honest. All I know is I somehow listened to one episode of TWIM and thru TWIM I found TWIV and I was hooked. There is quite a bit of the program that goes over my head, but I can normally get the jest of the conversation. Today I emailed the state University I live near to talk about enrollment. I already have some credit in Healthcare administration, but now I I’m thinking of diverting those if I can, toward Public health.

I’m not sure yet where I want to focus my studies but I’d decided if I only get to understand what you lot are discussing, I’ve gained a lot.

Maybe next time I write I will be able to tell you where in this large field I’m leaning.

Again, from someone who is just beginning this path, I love the show and keep it up!


Cristiano writes:

Dear “Twivelinos”

I work as a postdoc at the University of Otago, which is located in Dunedin, way down the bottom of the South Island of New Zealand. Thus, you can assume TWIV is everywhere, including the end of the world. I work at Andy Mercer’s lab, who, by the way, asks me to send his regards to Rich Condit.

Besides being a postdoc, I am also an aspiring science communicator specialized in natural history documentaries. I have suggested the topic of viral infection in the event of xenotransplantation before, with no success. Perhaps, I may have framed my suggestion in the wrong way, as I strongly linked it to a short documentary I made on this subject.

I can understand the potential political/commercial implications in discussing this issue, specially when it is associated with this particular documentary. Nevertheless I urge you to consider this discussion in the broad sense, without any mention to my film.

Xenotransplantation is a treatment for multiple diseases. However, at the same time that it may save lives, it poses serious medical and ethical issues, which may be of interest to your listeners. As provocative as it may be, xenotransplantation, as a topic, is perfect for the exercise of science communication. And who best to promote this debate if not the best in the field of Science Communication, such as the TWIV/TWIM crew?

I also would like to share another one of my clips. While listening to one of the TWIM programs I was inspired to work on an animation to explain the difference between prebiotics and probiotics. This was my first attempt in the world of animation:

I hope you consider my request.

Love both shows!

Best regards from the end of the world,


PS: Congratulations on 200 TWIVs!!!

Cris Felipe-Alves, PhD

Post-Doctoral Fellow

Virus Research Unit

Microbiology & Immunology Dept

University of Otago

Ken writes:

Dear TWIV-ers,

I’m a computer scientist who, as part of an Open Educational Resources project, implemented a web-based simulation of the Spanish Flu Pandemic. Six months ago while doing background research I stumbled upon TWiV 15 and have become a regular listener ever since. Using the model, students can explore different theories about where the virus originated. They can also run the model to explore counterfactual history — how different might the dynamics of the epidemic have been if there had been no war. Or if the war ended much later. (Interesting because Armistice celebrations and troops returning home occured during the second wave.) A guide to running the model is here: and a teacher’s guide is here:

I do have a question about Professor John Oxford’s theory of the origin of the Spanish Flu in a British Army camp in France — The virus would need to have infected people at the camp for over a year without significantly spreading elsewhere. For the computer model this meant a very narrow range of possible values for the transmission odds since a little lower and the infection dies out and a little higher and it spreads widely a year too early. Professor Oxford explains this by the heavy flow of new recruits into the camp so there is always a good supply of susceptible hosts for the virus. Outside the camp it doesn’t spread well. My question is whether there are known cases where a small fraction of a population were infected with a short-lived virus such as the influenza virus for a long period without the infection spreading or dying out?



P.S. The Spanish Flu simulator and resources are all freely available (Creative Commons) and might be a suitable Pick of the Week.

Fernando writes:

Hi Twiversarians,

Just got back from two weeks of ski mountaineering in Argentinian Patagonia and have listening to TWiV #199. In Argentina, some mountain huts (refugios) were closed because of hantavirus concern from the mouse overpopulation that was caused by the most recent instance of the coordinated bamboo flowering discussed in this paper: (there quite a few others on the topic).

As for Yosemite, answering some questions you asked in the podcast: Last winter was exceptionally dry in the High Sierra (Central Section plot in All but one of the cases involved people who stayed at the “signature” tent cabins in Curry Village, which are double walled: “The tent cabins where the victims stayed were signature models built in 2009. Unlike the other 300-plus tent cabins at Curry Village, the signatures have an insulating wall of drywall in addition to canvas siding. The two have a gap between them large enough for hantavirus-carrying deer mice to build their nests, park officials said.”

Sara writes:

Hi Vincent,

I came across your site as I was searching sites related to an article I wrote called “10 iPhone Apps for Tracking Kids Vaccinations” posted on my blog: ( . I thought I would reach back out to you to let you know about the article and to see if you would be willing to share it with your site’s readers.

Thank you in advance for your consideration!

Stephen writes:

In TWIV 200 you mentioned alternative careers for scientists.

There are two possible misapprehensions about science writing that might occur to listeners:

1. To be able to switch from science to writing about science, you must be a natural writer.

2. Anyone can write.

Both are wrong: You can learn to write, and you need to learn to write.

There are several science writing and science journalism programs in the US. I’ll suggest one as a listener pick of the week, the one I completed many years ago:

The UC Santa Cruz Science Communication Program

Here’s a quote from the About page:

> The science writing program at UC Santa Cruz has produced professional science writers since 1981. The program is one academic year long, with internships throughout the school year and the following summer. It focuses entirely on practical training through classroom work and diverse internships, and it’s the only graduate science writing program in the nation that requires a degree in science and experience in research.

The site includes pages about alumni and their writing.

Tony writes:

Hello Parisians. Here’s a Tumblr you might enjoy. “What I learned as a field biologist” Humourous anecdotes from the world of doing research in the jungles of the world. Here’s a sampler from the longer entry here

“You may then absentmindedly scratch some of the 200+ seed tick bites you have all over your body from 3 days prior (which it took 2+ hours to pick off with a pair of tweezers because you’re too hairy to use duct tape)…

In scratching said bites, you may then unknowingly transfer hookworm eggs (newly acquired from the aforementioned jaguar poop) from your fingernails into your skin at the bite sites…

You may then notice that some of your bites turn funny-looking and start to actually travel across your skin, and begin to itch so profoundly that if feels like your bones are burning, all because these particular hookworms can’t get through the human dermis…”

Enjoy. It’s a good laugh if nothing else. Keep up the good work guys.

Michael writes:

Hello again TWIVites!

Hello Dr. Racaniello

Hello Dickson

Hello Rich

Hello Allan

Hello to any guests that may be present,

It has been a while since I have written into the show. I became a regular listener in the late fall of last year and decided to try and catch up on all of the previous episodes before I wrote in again, but I just cannot help myself. I am only on episode 175 because my MicrobeWorld app stopped working for over three months and as a consequence I am just now catching up on the episodes from this year. I wanted to wait to write this email in case you guys ended up discussing this or something similar on one of your shows, but I can’t help myself – I need to get this out of my head and into writing before I forget to send it. So…here goes…

I had an idea while listening to one of your episodes about Influenza and reading Dr. Racaniello’s Flu 101 posts on his virology blog. I would like to get your thoughts on the matter if you would be so kind as to indulge me…

The Idea) Genetically modify the domesticated swine and fowl in the world to either under express or better yet NOT express the sialic acid receptor on the surface of their respiratory epithelium via gene knockout.

The Goal) To limit or eliminate the spread of influenza through the domestic swine and fowl populations as well as the subsequent transfer of flu between the two populations and humans. The ultimate goal would be to stop the emergence of pandemics that arise from these two domesticated animal populations that take thousands of lives every year. If these pandemics could not be stopped then at least the viral evolution that takes place in these populations via genetic sharing during a co-infection could hopefully be slowed down to a crawl.

Dr. Racaniello, in your Flu 101 posts you state that Influenza binds to the sialic acid receptor on the respiratory epithelium in order to gain entry into those cells and begin replication. My thoughts were that if the receptor isn’t there…the virus can’t get in…can’t replicate…and can’t spread into the blood stream to infect other cells that contain that receptor (such as RBC’s).

Some Caveats)

1.) The sialic acid receptor performs some essential function that I am unaware of and could not be eliminated.

2.) It may not be possible to selectively knockout the gene JUST for the sialic acid receptor.

3.) Getting rid of the sialic acid receptor might force the virus to evolve an affinity for a different receptor that may make it more dangerous or deadly.

* 4.) Even if this is successful, it would NOT affect the spread of virus through wild swine and bird populations.

5.) The scale of this project might be too large and hence put it out of reach. The cost would likely be tremendous.

6.) The anti-GMO crowd would NOT be happy about this.

I was wondering if you guys think that this could be done – if only in theory? Please tell me your thoughts.

* This may not matter all that much since (as far as I am aware) most flu transmission between people and pigs/birds occurs during close contact between agricultural workers and the domesticated varieties and not from the wild ones.

With warm regards and much thanks for a wonderful podcast,


Elle writes:

Absolutely love your show, it has renewed my love for this particular sector of science and inspired me to reach for a career in microbiology and immunology. Please do not stop what you’re doing!! There is a lack of educational yet exciting medium out there, if we had more people like you in the world “honey boo boo” wouldn’t have left the cutting room floor. Recently there has been a ruling in canada: I’m wondering what your thought’s are on this issue. In a previous show in 2011 you touched base on how low virulence load’s are virtually undetectable by standardize test when given the proper treatment. However I was curious if immunosuppressed individuals have an increased risk of exposure? And with the evolving rate of viruses, what is the risk factor of a individual no longer responding to anti-retro’s like HAART even after taking it for many years?

PS: Thanks for expanding my collection of books that my poorly put together Ikea bookcase can no longer support. 🙂


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