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Letters

TWiP 65 letters

 

Perry writes:

Greetings Vincent and Dick,

Hooray for finally mentioning G. pulchrum in episode 62, my most favorite parasite and one worthy of further discussion. As a diagnostic veterinary pathologist, I encounter this spirurid in approximately one third of the dairy cows I autopsy. It is much more common than you surmised. I make a big deal out of its frequent occurrence, not because of its pathogenicity (essentially none), but because it is a paradigm organism. It insinuates itself in the esophageal mucosa, wriggling back and forth in the epithelial layer as it advances (that is why it is called the 'ribbon candy' worm) thereby maintaining its hold and evading immune surveillance. The paradigm is that it is a beautiful example of an innocuous host parasite realtionship and the fact that most diagnosticians readily overlook it. Students of pathology all too often 'look' but fail to 'observe'. A south african veterinary pathologist told me that Gongylonemiasis occurs in the mouth of poor ruaral children, presumably due to the ease with which they ingest an infected beetle intermediate. It has been some time since I last reviewed the literature, but I believe the nematode is world-wide and capable of parasitizing innumerable mammalian species. I enjoy your program, biomedical science musings and digressions. Keep up the good work.

Curt writes:

Hello, Vincent and Dickson!

First, let me start with some praise. I thoroughly enjoy all of the TWiXcasts, but I appreciate TWiP in particular for its one-on-one format and the wealth of clinical experience and case studies that Dickson brings to bear in every episode. I finished Vincent's outstanding Coursera course recently- looking forward to part two, on that note- and it set me to wondering when Dickson is planning on doing a Coursera class on parasitism.

I'm writing because I'm curious if the military has ever tried to weaponize helminths. I'm aware of past efforts by the military to weaponize practically everything, especially in the realm of pathogens- running the spectrum from from Y. Pestis and Smallpox to Coccidiodes fungi. I wouldn't imagine that an attempt to weaponize helminths would be very successful, though, and attempts to imagine such a program are baffling at best.

Keep up the outstanding work, gentlemen, and thanks again for your time and effort.
-Curt

Cathy writes:

Dear Professors Despommier and Racaniello,

I wanted to write to you to thank you for taking the time to do these fantastic podcasts. TWiP was recommended to me by a former colleague with whom I worked in Professor Paul Duprex's virology lab at Queen's University Belfast, before he moved to Boston University. Since working with Prof. Duprex I got my PhD in molecular parasitology, and now I work in St. George's University of London on the nanomal project (the link for which I've included) which you may find interesting:

www.nanomal.org

We're developing a hand-held point-of-care diagnostic device for malaria that can give a diagnosis in under 20 minutes, but the really exciting part is it will be able to speciate and detect drug resistance-conferring mutations so an informed treatment choice can be made.

Being a malariologist I particularly enjoyed TWiP#35 with David Fidock, and my interest was especially piqued when the contentious subject of artemisinins' mode of action was brought up. I thought this was about to be explored but alas, it was not. Of course, there are not enough hours in the day to debate that subject. If you are interested, however, we recently published an opinion article in Trends in Pharmacological Sciences on the subject which I have attached. Professor Fidock mentioned the haem hypothesis, but I am more in favour of the SERCA hypothesis, which postulates that artemisinins specifically inhibit the sarco/endoplasmic reticulum calcium ATPase (SERCA) of the plasmodia parasites. People may feel that knowing the mode of action of a drug is purely academic, but as you are well aware drug resistance is a serious problem for controlling malaria, and knowing how a drug works can help identify any mutations responsible and hopefully overcome resistance.

Thank you again for all the time and effort you put in to these podcasts. I have thoroughly enjoyed learning about different parasites, not to mention american history and piscatorial pursuits, and constantly recommend TWiP to my fellow parasitologists. I plan to start listening to TWiV but it's been quite a while since my virology days. I hope I can keep up!

Yours sincerely,
Cathy

Lisa writes:

Hello to Vincent and Dickson, TWIP

First may I say, that it's great you are putting such in-depth content out in the public domain, People such as yourselves, with vast amounts of knowledge and years of experiences giving your knowledge freely is fantastic and I apualde your for it. And not to mention your presentation style is superb and funny.

The Microbe world fascinating to me, I bought a decent Amscope microscope last year, I have always wanted one but after getting into TWIV /TWIP /TWIM, I finally bought one. I've used it many times looking at pond life/mouth bactria/poo from my dog "Bella" who is female and very coprophagic towards next doors cat :( I basically put anything i dare put on a slide to the horror of my fella, Our daughter loves it too, with all the "yucks" and "Errrs".

Anyway to cut a long story short, Not that I have been waiting for a decent infection but last week I contracted what I thought could only be described as food poisoning, after 24 hours of (diarrhea/vomiting/burping/feeling bloated/major cramps) I thought the best thing to to is check a stool sample, naturally..... As I had never been so ill
My thoughts were that it could be Food poisoning but i wasn't convinced, after going back and hearing TWIP #16 Giardia Lamblia it rang a few bells.

On investigation all could see no Giardia Cysts but I could see many uniform tubes with constrictions at the end, Being uniform and tube like my first thought was Dog Tapeworms? Or could it just simply be something I ate as it looks like plant matter, I'm sure if it is parasite debris then Dickson can identify it in a jiffy.

After searching Google to no avail, I feel I may need a copy of "People, Parasites, and Plowshares" for future use?

Here are a few pictures of the tube like forms? Seeing as though Dickson has seen many stool samples in his time, I thought it to be great opportunity to write in and express my gratitude for all the great work you are doing plus a token of that appreciation.

Keep up the good work and thank you so much for bringing science to the rabble.

 

TWiP 64 letters

Richard writes:

Good morning, day, evening (depending on your time of day). Esteemed professors!

Firstly my weather report, for Weston super Mare, uk.

It is currently 3 centigrade (feels like 2C), dew point 4C, humidity 78%, there has been 1mm of rain/sleet, with a 50% chance of further precipitation, and the wind is 16 km/h from the WNW. It is currently dark so no visibility, but this is estimated as 2 miles, as it is cloudy with light rain.

The predicted high for the day (2PM) 9C, with humidity of 68%, and dew point of 4C, with predicted wind of 21km/h, a 40% chance of precipitation (rain or sleet), to is expected to be partly sunny, with good visibility >10 miles predicted.

I hope the weather report meets your increasingly exacting requirements :)

My question is actually fairly simple; Giardia lamblia and a number of other eukaryotes lack mitochondria. Most of them appear to be anaerobic, and I can see the point that the mitochondria and electron transport mechanism might well be selected against.

However, no where can I find if it is clear that mitochondria where selected against, and lost. Or if these bugs are a branch, that where started before eukaryotes adopted mitochondria.

I'm not scientist, but simply an interested party. I actually work as an engineer, on sewage treatment plants. So I do get to see a lot of bacteria, since they do all the work, treating the sewage. Given plenty of oxygen, and the correct nutrients, they do a fine job of this, and then happily settle out, leaving clean enough water that it can be returned to the environment (or with minimal treatment, and filtration, to the drinking water supply, as is becoming more popular).

However it is my personal theory, that apoptosis in eukariotic cells derives from the incorporation of a once parasitic bacterium. Such a parasite requiring a method to kill the host cell, in order to proliferate into the medium, to infect other cells. I hypothesise that this was co-opted by eukaryotes, in order to allow for apoptosis (or programmed cell death).

Knowing if apoptosis odours in eukaryotes, that lack mitochondria, and if they are a pre mitochondria branch, would answer my question. However I have been unable to find the required information.

I wonder if you can point me in the right direction, and also thought the subject might lead to an interesting conversation on the podcast.

Many thanks for your ongoing series of podcasts.

I have emailed this to both TWIP, and TWIM. I suspect it is better suited to TWIM, but my research has been on parasites, since these seem better studied, so have included TWIP.

Thanks in advance for any insights you may be able to provide, or simply interesting conversation.

Regards

Richard

Dave writes:

 

Hiya! Entering mid-dialogue, so sorry for out-of-touch points hereafter. Trivial anyhow.

As to fuel powered machines and discovery of oil deposits (identified as refineable fuel, since deposits were mined for minor purposes in antiquity), um, as I recall, Henry Ford intended his internal combustion engines to run on ethanol at the outset. I have no idea how far earlier the engine-makers planned ethanol, but.... Anyway, Rockefeller et al came along shortly to amend all that. Besides, obviously y'all were perfectly accurate about all that machinery thing and slavery.

More to the point of parasitology, another trivial emendation may be that the first hookworms didn't necessarily enter N. America on African feet after 1600. West Africans had been transported to Caribbean islands for labor by mid 1500s. They may have inoculated soil there with hookworms, which may have been picked up by sojourning barefoot non-Africans, and transported to N. America first by those people after 1600. Maybe. (If I haven't misremembered the true mid-century. Got it from "Diary of an Irish Slave Girl," a novel about a kidnapped child who was taken to a British sugar plantation and ended up marrying an Ashanti man. Therefore my historiography may be off. But I do think those island plantations were started up in the 1550s or so -- and, from other sources, European population growth began to explode, apparently correlated with sudden availability of enough extra calories to delay starvation, preserving more children, etc.)

So anyway. Hope It's not wasted your time. Entertained me, but not enough to edit it down.

Dave

Benedict writes:

Hello,
I love your show, I hear it on the way to work and home again each day. Would love to hear during work as well but my coworkers would complain I guess. I have a question regarding the theme song at the beginning of twip63. What song/remix is that?
Kind regards and all the best!
Benedict

John writes:

Dear Professors,

I have listened to you discuss parasitic diseases in mice, fish, mosquitoes, ladybugs, cats, and even humans, and feel you have paid relatively little attention to squirrels. A recent paper in BMC Veterinary Research could help cure that deficiency.

http://www.biomedcentral.com/1746-6148/9/229/abstract
http://www.theguardian.com/environment/2013/nov/18/red-squirrels-threat-humans-pets

British veterinarians studied 163 dead red squirrels. The squirrels were mostly found near houses and roads, and half of them were killed by cars or pets.

The dead squirrels were examined to determine cause of death and inventory parasites and other disease causing agents.

I spotted at least four eukaryotic parasites -- three Apicomplexa and a nematode -- only one of which I recall hearing about on TWiP.

Toxoplasmosis was blamed for one sixth of squirrel deaths on the Isle of Wight. It was considered a direct cause of death rather than a contributing factor like when it prevents mice from avoiding cats.

Hepatozoon infections were common in lungs and heart muscles, and Eimeria in gut contents, but neither seemed to be a primary cause of poor health.

The last parasite is so obscure it does not even have a Wikipedia page. It is related to pinworm, which you have discussed. Quoting the paper:

"Nematodes were sometimes observed during gross and histological examination of intestine. Morphologically they resembled pin worms (Enterobius sp.) but, apart from one case where they were identified as Rodentoxyuris sciuri, none were submitted for species identification. Typically there was no apparent associated pathology but one juvenile with a heavy nematode infection died due to an intestinal intussusception. However, in a second case of intussusception involving an adult there was no significant worm burden and the aetiology was obscure."

The squirrels also had viruses and bacteria, in case you want to have a squirrel week across all three "this week in" podcasts, end ectoparasites and fungus if you want to expand to five podcasts.

Suzanne writes: 

I couldn't remember being tested for Toxoplasmosis with any of my pregnancies while listening to your most recent podcast so I looked it up. According to MayoClinic.com most women aren't tested automatically these days. I didn't find any specific recommendations anywhere, though, so maybe it's something that depends on the doctor.
I do remember tests for AIDS and Hepatitis. Especially since with the most recent one the lab gave me someone else's positive Hepatitis result and missed my anemia :p
These days they just tell every pregnant woman to avoid under cooked meats and litter boxes.

Suzanne

PS It's cold down here in central Texas! I can translate easily from Fahrenheit to Celsius because it's been hovering just above 32F/0C for the last few days. We may even get what passes for snow around here... a few flakes mixed with the rain. I expect by next week it'll be shorts weather again, though.

Maybe that would make more sense as While listening to your most recent podcast, I couldn't remember being tested for Toxoplasmosis during any of my pregnancies...

Sam writes:

Hello TWIP! I write to you again from Tucson, where we are having quite a warm December. Today was a beautiful day, 75F, with sunshine and scattered clouds.

I was listening to Dickson explain the difference between Plasmodium vivax and P. falciparum on a historical TWIP whose number I don't recall, when later that day what should I read but the links below, reporting P. vivax infections in Duffy negative humans. The articles report that duplication of the Duffy binding genes seems to enable infection even without the Duffy receptor (per http://www.eurekalert.org/pub_releases/2013-11/cwru-vmm111413.php another report is expected 12/5, in just a few days).

It seems odd to me that duplicating this gene would have this effect - after all, wouldn't this be like having multiple keys to a door with no lock? It must be using a receptor of some kind, right? If it's not using Duffy, then it must be using another one - is Duffy part of a family of related receptors, or has the gene duplication produced a match for some other receptor altogether? I also wonder how this mutated parasite will fare in ordinary Duffy positive humans. I'd love it if you all could revisit this topic on the show.

On an unrelated note, I must say that the presentation of this open access paper (link below) is really great. No truncated article, clear navigation and organization, and it even includes a twitter interface. Three cheers for PLOS!

Thanks again, Victor and Dickson, for the podcast - Sam

http://www.plosntds.org/article/info%3Adoi%2F10.1371%2Fjournal.pntd.0002489

http://www.sciencedaily.com/releases/2013/11/131115094906.htm

 

 

 

 

 

 

TWiP 63 letters

 

Helen writes:

Hi,

As a new listener, I don't know whether you've later corrected this or not, but you got several important things wrong in describing the antebellum South in the first episode on Hookworm. They did have machines, and they made good use of them. What they did not have was factories, because they were making plenty of money farming on the backs of unpaid slaves.

The first Africans arrived in Jamestown in the early 1600's, not long after the European settlers arrived. (You said the 1830's.) The cotton gin was invented in 1793. It made cotton farming *far* more profitable, greatly increasing the slave trade until the international slave trade was banned in 1808. Internal slave trading continued, and the slave population continued to grow dramatically because the slave women were forced to have as many children as possible. Children born to female slaves became slaves, whether their fathers were slave or free. "Due to its inadvertent effect on American slavery, the invention of the cotton gin is frequently cited as one of the ultimate causes of the Civil War." The American South provided two thirds of the world supply of cotton by the start of the Civil War.

http://en.wikipedia.org/wiki/Cotton_gin
http://en.wikipedia.org/wiki/Slavery_in_the_United_States

So hookworm must have been endemic long before the Civil War. There wasn't much more introduction after 1808. However, substantial parts of the South were still under Native American control, and thus perhaps free of hookworm, until the Trail of Tears forced relocation in 1830, and the land was sold for agricultural use.

http://en.wikipedia.org/wiki/Trail_of_tears

Also, there was slavery in the north, though certainly not as much. There were still slaves in New Hampshire and New Jersey until the emancipation proclamation in 1865. Other northern states had banned it earlier. Southerners brought their slaves with them when they came north. You can see George Washington's slave quarters in Philadelphia across the street from the Liberty Bell. Slaves who got their freedom in various ways migrated north.

http://en.wikipedia.org/wiki/Slavery_in_the_United_States

The American history mistakes start about 10 minutes into the episode.

Thanks for a great podcast!

Anna writes:

Hi Dickson and Vincent,

I recently started listening to TWIP and TWIV, and I love them both! It's been hard trying to catch up and listen to them all (needless to say, I'm not even close).

I'm wondering if you guys know of any neotropical parasites (or viruses for that matter, I just thought parasites might be more likely) that live some part of their lives in both snails and bats.

I'd appreciate any thoughts you may have :)

Thanks so much!!

Neva writes:

Hi TWIP Twosome,

http://bittelmethis.com/bats-bombs-project-x-ray/

A story about how the US planned to weaponize bats during WWII.
Ed Yong tweeted this. What a batty tale.
You guys are da bomb,

Neva in Buda TX

Shane writes:

Hi Dickson and Vincent,

I listen to every episode of Twiv, Twip and Twim and often follow along with Wikipedia to help me understand terms i am not familiar with and also check out most of your picks.

I also watch Monsters Inside Me with my 12 year old daughters. I am up to Season 2, Episode 3 and was just wondering if you (Dickson) were still advising on this show?

In this episode a man got very ill and his spleen swelled to 5 times it's normal size, after a battery of tests finally a test for leishmaniasis came back positive, would this be visceral leishmaniasis?

I didn't pick this as I would expect some sort of skin lesion. Also they treated him with anti-biotics and he recovered, I am only a computer programmer but I would not think anti biotics would be the recommended treatment for leishmaniasis

Thanks for the awesome work of the entire TWIx crew puts into producing these podcasts

Shane from Australia
P.S. It's a balmy 20 degrees C at 11pm

Bernadeta writes:

Dear TwiP'ers,

I recently found out that when my mum was pregnant with me she was tested for toxoplasmosis, and it turned out that she had very high titres of IgG against toxoplasma. However, she took no treatment, and had absolutely no symptoms of disease. I turned out ok, I think, so it doesn't seem to have done anything bad. So I was wondering, are all pregnant women tested for toxoplasmosis and if so why? My mum was pregnant in 1992 and it was in Lithuania, so I wouldn't be surprised if things have changed from that time or have always been different in US. Does carriage of toxoplasma pose any threats for pregnant women and their foetuses? Also, Is it likely that I now have antibodies against toxoplasma because my mother was infected while pregnant?

Best wishes,

Bernadeta

 

TWiP 62 letters

 

Blaine writes:

Hi Twippies,

I saw today in the New York Times that a hookworm vaccine will be tested in Gabon. I found this very intriguing as your discussions of parasitic worms have rarely included the possibility of vaccines. Can you please comment on this. Are there certain biological challenges to making vaccines against worms? Or is there simply no money in making these vaccines since they are not needed in rich developed countries? It seems to me that it would be much simpler (and cheaper) to just educate people on how to avoid most of these parasites than to produce a vaccine. Simple practises, such as digging your outhouse six feet deep, or curing your feces before using it as fertilizer would eliminate many of these parasites. I would love to hear your comments on this matter.

Sincerely
Blaine
Fort McMurray, AB, Canada

PS. The Link to the NYTimes article is here:
http://www.nytimes.com/2013/10/15/health/parasites-hookworm-vaccine-will-be-tried-in-africa.html?_r=0&adxnnl=1&src=rechp&adxnnlx=1381850510-85vsLPkuDrCO6Lb3r7SoDg

John writes:

In a local newspaper:

"Zoonotic research taking Framingham man to Peru"

http://www.metrowestdailynews.com/features/x1155177408/Zoonotic-research-taking-Framingham-man-to-Peru

Robin writes:

Parasites may be sneakier than we surmise:

Transformation of malaria parasites by the spontaneous uptake and expression of DNA from human erythrocytes

http://m.nar.oxfordjournals.org/content/29/3/850.full

We may have more baggage than we know:

Invasive Genes: Humans incorporate DNA from parasite

http://www.phschool.com/science/science_news/articles/invasive_genes.html

Jim writes:

Hi,

A pdf made from a local newspaper article is attached concerning a biologist who found a nematode embedded in his mouth. The article is available online from The Daily Press, but you have to subscribe to read it. I assume it's ok to make the pdf available to your listeners, if you desire.

Regards,

Jim
Smithfield, VA

Mike writes:

Hi Guys,

I know that insect larvae are much bigger than your usual fortey, but I find the bot-fly life-cycle fascinating. I don't think it can be defined as an ecto-parasite, as it actually develops inside the skin, not on top of it. Care to discuss it a little? I would love to hear your take Dick.

Thanks!

Jim writes:

Here's another one, and I quote,

"A scientific discovery falls out of this epidemiologist's nose
Tuesday, October 15, 2013 1:28 PM

Imagine finding a tick up your nose — and being happy about it.

Epidemiologist Tony Goldberg was working with primates in Kibale National Park in Uganda. But, when he returned to his lab at the University of Wisconsin, he began feeling some pain in his nose.

That's when Goldberg discovered a tick inside his right nostril. Definitely not something that's cause for celebration, usually.

"I made use of a mirror, a flashlight and some forceps to remove it," Goldberg said. "I was fortunate to grasp it firmly by the mouth parts and I got the tick in its entirety out of my nose, sparing the surrounding nose hairs."

But, being a man of science, after he removed the tick, Goldberg analyzed its DNA.

The nostril tick belonged to the genus Amblyomma. But it didn't match any known bugs in various databases.

That means it could be a tick that hasn't been genetically characterized yet — or a completely new species.

"We're still learning the pathways that diseases can use to move between wildlife and people. And this nose tick is a slightly amusing and particularly gross example of how diseases move in nature," Goldberg said.

Jim
Smithfield, VA

Raihan writes:

Dear esteemed and honoured Professors,

I'm writing in response to TWIP 57 where in the intro Prof Despommier mentioned that he had just returned from Singapore. The question was asked if water is spins clockwise or anticlockwise down the toilet since Singapore lies 1 degree north of the equator and I am pleased to announce, as a Singaporean, that water spins anticlockwise in Singapore.
I just did this experiment in my lab sink and toilet. Finally, I've produced some research worth noting.

Apparently the fact that it does not spin clockwise here has been noted before (check out the last paragraph). But i'm still searching as to why this is so. I do know that the coriolis effect is strongest away form the poles and that it does not have much of an effect on small sinks, ie, you can easily push water in the opposite direction and the water would willingly change its course, but none of these explains why the water rotates anti clockwise.

Raihan
A student in virology, not so much in the coriolis effect.

Jim writes:

Just got this link to an Australian Video via Digg in case it's of interest.

Jim
Smithfield, VA

 

TWiP 61 letters

Ian writes:

Dear TWiPers,

I just finished listening to the superb Twip #56 and I am thrilled because I am a huge fish nerd. In fact I spent much of my youth catching and chasing fish on the same lovely New Jersey barrier island mentioned in that episode. In my enthusiasm, I wanted to write in with a few thoughts.

The first is nit-picking, but the gar discussed around the 13:00 minute mark is more likely a specimen of Atlantic Needlefish, Strongylura marina, than a member of the “true gar” family Lepisosteidae. Like members of Lepisosteidae, needlefish have elongated, tubular body plans, and are sometimes referred to in common usage as gar. Needlefish often spend time at the surface, but do not gulp air in the cool way fish such as the Florida Gar do. This mix-up might explain Dickson’s surprise at hearing about gar so far north.

As an aside, I might add that I have heard that --if presented with a fly small enough to fit in their diminutive mouth--needlefish make for wonderful sport fish. I myself have caught a needlefish on Barnegat Bay, although not in the manner one might think. I spend my free time sailing a catamaran around the bay. On one windy day I had the rude surprise of a large needlefish jumping out of the water and landing in my boat! My crew and I were as shocked as the fish! It was a memorable experience; particularly because, like many angry fish, the needlefish displayed a heightened, more vibrant coloration than I usually get to see. The fish was promptly returned to the water and I was left relieved that I hadn’t been added to the list of people who have been impaled by needlefish (http://the.honoluluadvertiser.com/article/2005/Jul/30/ln/507300340.html).

In the spirit of “This Week in Fish” I would like to suggest “The Founding Fish” by John McPhee as a pick of the week. The book is a wonderful examination of everything Shad, written by a wonderfully gifted writer. I’m picking it because Twip #56 included a question about shad’s tastiness. As the book points out, the species name of the American Shad, Alosa sapidissima translates to “most delicious”. I am salivating just thinking about a meal of baked shad, perhaps with a side of Atlantic blue crab, whose species name also derives from sapidus the Latin word for savory.

As always, much thanks for all the work that goes into the TWiX podcasts. I am about to leave on a road trip across the US in order to start grad school for biology, and I am looking forward to having tales of viruses, microbes, and parasites keep me company along the way.

Thanks,

Ian

Howell writes:

Dear Professors,

First of all, thank you for producing such fascinating podcasts! I got interested in parasites when I read Carl Zimmer's book - I've just discovered TWiP, through Professor Racaniello's course on Coursera, and I intend to try and listen to them all!

I've just got one question so far: is the cover photo for the page of Trichinella?

Thanks

Andy writes:

Dr. Despommier,

I enjoy your show although parasites are not related in any way to what I do for a living.

You have mentioned the death of the S. A. Andrée's Arctic Balloon Expedition of 1897 crew in a couple of TWIPs including in episode 60 and how they probably died of Trichinosis from eating polar bear.

http://en.wikipedia.org/wiki/S._A._Andr%C3%A9e's_Arctic_Balloon_Expedition_of_1897

I was fascinated by this and repeated it a couple of times to friends, but when I was looking for details I came across this entry in Wikipedia which says this theory was "discredited in 2010." The cited links are in Swedish and one appears to be broken at this time. The other one is very brief but using google translate it says they think it was polar bears instead. Obviously anyone can put whatever they want on the internet, but I wonder what your thoughts are on this?

Andy

Tommy writes:

Dear Vincent and Dickson,

Just a note about something that Dickson mentioned in TWiP 60, I am sure Dickson realised that he simply misspoke after it went on air, but the digenean responsible for the "Barber Pole Effect" - Leucochloridium paradoxum - is not a schistosome but belongs to the Leucochloriidae family which is on an entirely different branch of the digenean/fluke tree to the schistomes.

There are many different species of Leucochloridium and they come in different colours. For example Leucochloridium paradoxum have green bands or red-brown bands on its sporocyst brood sac (the structure which invades the tentacles of the infected snail) whereas Leucochloridium millsi has yellow or orange-yellow bands. A good paper on this topic can be found below.

Kagan, I. G. (1951). Aspects in the life history of Neoleucochloridium problematicum (Magath, 1920) new comb. and Leucochloridium cyanocittae McIntosh, 1932 (Trematoda: Brachylaemidae). Transactions of the American Microscopical Society, 70(4), 281-318.

Additionally, there is some indication that the behaviour of the snail is altered, as noted by Carl Wesenberg-Lund in this paper below.

Wesenburg-Lund, C. (1931). Contributions to the development of the Trematoda Digenea. I. The biology of  Leucochloridium paradoxum. Memoires de l'Academie Royale des Sciences et des Lettres de Danemark, Copenhague, section des sciences 4, 90-142.

It was cited in Janice Moore's 2002 book "Parasites and the behaviour of animals". Wesenburg-Lund noted that "It seems as if the infested snail seek the light; they are very often see balancing on the borders of the leaves, or sitting on the underside of the leaves with only the antenna infested with the Leucochloridium protruding from the border
of the leaves..."

Now compare this with the behaviour of most terrestrial snails which prefer more damp and secluded surrounding. Such altered behaviour would expose the snail (and it brightly coloured parasite) to predation by the potential bird host.

As a side note, here is a link to a cartoon I drew about Leucochloridium a few years ago
(http://the-episiarch.deviantart.com/art/Zombie-snail-parasite-181904859).
It contains a pop culture reference, which might not be obvious to everyone, though most people below a certain age would immediately recognise it. For the listener who cannot see the imagine, it is a reference to the 2003 song "Milkshake" by Kelis.

Keep up the good work Vincent and Dickson, I look forward to more parasite tales from you in the future.

Robin writes:

Toxoplasmic humans

'Tain't just mice that have adverse behavioural outcomes with Toxoplasma.

http://www.biomedcentral.com/1471-2334/9/72

http://www.biomedcentral.com/1471-2334/2/11

http://www.sciencedirect.com/science/article/pii/S0379073809001224

http://www.parasitesandvectors.com/content/5/1/13

Should humans attacked or killed by big cats be checked for Toxoplasmosis?

Suzanne writes:

Thank you for the Bt and mosquito info. I had a feeling there had to be a catch. Since there's always plenty of other water that isn't treated I expect Bt wouldn't become completely useless but it's good to know it's not a wonder fix, either. Ah, well.

TWiP 60 letters

Maureen writes:

Our vaccine unit here at NIH did a study of malaria vaccine with some promising results. I know Dickson has been a champion of conquering malaria.

http://www.sciencemag.org/content/early/2013/08/07/science.1241800.full


Spencer writes:

Dear Vincent and Dickson,

I just received a confirmed case of Cyclospora from the lab on one of my patients who has had several weeks of diarrhea. It appears to be the first one in New Jersey. The patient ate salad that tasted rotten in a local supermarket salad bar. Good thing I am a loyal and avid listener of TWIP! BTW - I am reading "Peoples, Parasites and Plowshares" and I'm really enjoying every page but my wife is scared of the cover!


Spencer Kroll MD PhD

Dr. Steven Reeves writes:

I discovered this podcast only in the past few months. Love it! I am a practicing Internist in a small (8,000 pop.) community in Iowa. I listened with interest as you discussed the ongoing cyclospora outbreak. Just as a point of interest I have three patients in my practice with a confirmed diagnosis. What I also wonder is whether we are experiencing an observational bias?? We are finding cyclospora because we are looking for it. In addition, when we send stool specimens for evaluation (culture, O&P and WBC) we must specifically ask for cyclospora testing just as we must also ask specifically for Norovirus. I find this interesting and wonder if it might be playing a role in the current numbers. Thanks again for a great podcast!!! BTW: temp today is a perfect 76 degrees F. Finally!! We have been in the grip of a heatwave.

Trudy writes:

Dear Vincent and Dickson,

I'm writing this email because of a comment made by Dickson on TWiP 57 regarding the CDC. Dickson mentioned that the CDC was underfunded and the campus still looked like something out of the 19th century. I was wondering if Dickson has visited Roybal campus (the main campus) since the turn of the millennium? A series of renovations took place starting around 2003/2004, and almost all buildings have since been replaced. The end result is quite stunning, with the campus resembling a booming metropolis (I included a link with pictures).

Unfortunately, this change has not really been reflected in scientists' salaries, and according to most standards, I would say that compensation is still less than adequate, especially considering the nature and complexity of work being done there.

cdc

Anyway, be well and keep TWiPping!

Trudy

Jim writes:

Howdy,

This is for Dickson. The Dec 73 National Geographic has an article about Greenland which says on p 867,"We were crossing a frozen inlet," he recalls, "when we went through the ice, losing our food and nearly all our equipment except two sleeping bags and a tent. We scrambled ashore with the dogs.

"I knew there was a trappers' hut up the coast, probably with a cache of food. In the meantime we could always eat the dogs in an emergency -- or so I thought, until the weather took a sudden warm turn.

"You see," Steen explains, "some Greenland dogs, like others in the Arctic, carry trichinosis. Dogs seem to be only mildly affected by this disease, which is caused by small worms. To humans, it can be fatal.

"To kill the worms, you either cook the meat or let it stand for several days at below-zero temperatures. The only trouble was that we had lost our stove fuel and the temperature stayed above zero."

In fact, it stayed above zero for three weeks, while a snowstorm raged. In their tent, the men grew weaker each day At last the snow stopped and they managed to walk and crawl to the hut -- followed by the dogs, who were even weaker than they. A trapper making his rounds finally rescued them.
=========================================

I can send a pdf of the article, if you want it, or the hard copy for which I'll need an address. I've just dismantled a bunch of the NG's to extract indian-related material for a relative in Arizona after learning the whole magazines can't be sent by media mail because they contain advertisements! They weight about a pound each! Too bad.

Regards,

Jim
Smithfield, VA

Robin writes:

Why can't Dr. Dickson TWIP via Skype when away?

Howard writes:

Dear Esteemed and Erudite Professors,

I’d like to revisit something Dr. Despommier said about why the whole sporozoite vaccine produces immunity whereas natural infection does not. He was surprised that intravenous injection of the sporozoites was effective vs the natural way of the mosquito injecting them into the skin. I’m pretty sure if he listened to the episode later he realized he misspoke since the female mosquito indeed delivers the parasites intravenously because that is where it is getting it’s blood meal. The abstract of that paper in science contains what the authors believe is the reason it works. “These data indicate that there is a dose-dependent immunological threshold for establishing high-level protection against malaria that can be achieved with IV administration of a vaccine that is safe and meets regulatory standards.” The series of injections delivered a total dose of between 540,000 (30% protection) and 675,000 (100% protection) attenuated sporozoites vs. the much lower numbers of infectious sporozoites delivered into venules by the vector. From the parasites’ point of view less is better since a few continue the replication cycle whereas many would cause immunity or possibly death of the host by overwhelming infection.

As always, thanks for continuing to make these three series of the best science podcasts available in the universe.

Blaine writes:

Hello Twipsters,

I found this delightful account of a beef tapeworm infection on the internet:

"The Worm Within" http://www.fray.com/drugs/worm/

It is a fantastic read that I am sure many listeners would love to check out.

Yours in parasitology,

Blaine
Fort McMurray, AB
Canada

Jim writes:

Foyle’s War episode invoving a tick bite.

It's noteworthy by its rarity. Here's the link to an episode description which omits the tick, but the bite is crucial to the ending! Some good British TV.

Jim
Smithfield, VA

Suzanne writes:

I have a question possibly more related to TWiP. I've heard a couple of gardening radio show hosts mention making a mosquito trap out of standing water with mosquito dunks (Bt) in it. The idea is that any area mosquitoes lay their eggs there and don't go looking for other places with standing water. The larvae are eaten and you have fewer mosquitoes in the next generation than you would have if you'd just emptied all the standing water you could find. I was interested to hear what Dickson thought about that.

TWiP 59 letters

Allan writes:

You have the best podcast on the web, hands down. I use your TWiP episodes in both my undergraduate and graduate classes.
Thanks.

I've recently seen a family in Hawaii with recurrent pathogenic Blastocystis hominis and Dientamoeba fragilis and I'm suspicious if they are getting it from close association with feral pigs. I see a little published on the possibility from Italy, but do you know how prevalent it is in pigs and particularly, does D. fragilis even have a transmissible cyst stage? Are both of these parasites considered emerging pathogenic diseases?

Any suggestions on setting up an investigation to answer these questions?

Best regards,
Allan

Allan Robbins, DIH, MPH
University of the Nations-Global Health

Andrew writes:

Hi there,

My name is Andy- I was wondering if you may be able to provide me some feedback on something I'm developing. I'll try to make it explicit as possible. First off, I was wondering how difficult it is to engineer a Virus's Ligands to match up with a desired Host Cells surface receptor. The relevance behind my first question is, would it be possible to engineer a virus that can attach to T. gondii surface receptors and ultimately infect the parasite? Of course there are lots of things to consider, but I'm really only curious of the concept itself. I haven't found any literature that specifically applies to my question, so I've turn to you! Any thoughts? If engineering is possible, Viable infection would be the first step and then developing an idea on how to kill the parasite would be the following (in my amateur perspective at least).

Karl writes:

Sent from my iPhone hi you guys I am Karl from Northern Ireland :) . I would like to thank you for all the weird and wonderful information about parasites viruses and bacteria and general information discussed in you topics. It has been a pleasure writing about it so I don't forget it which helps keep me informed and can read over to remind myself of all the parasites as there are so many. I am a chef in the food industry and reminds me to be careful when handling raw food products I always were latex gloves now to keep me protected and think that more people in the catering industry should be put through a parasite awareness course for themselves and others. I say this because of my own experience of having a parasite in my body which thankfully was taken care of . :)). I am now a vegetarian and have never felt better. I have evolved at last haha. It's like the Adam and Eve story and the serpent and to choose what to eat and knowing what is good for us and what is bad for us. The ancients spoke and drew of the ouroborus now I understand what it all means. We are part of the food chain not at the top . So makes me think what is are purpose to be food for parasites so the can live and survive amount us secretly . Makes me wonder if mars has water ??,,,is there forms of parasites that may exist there also . Anyway don't want to write a book about it for use to read just taught of saying thanks again and look forward to continuing to listen to the both of your podcast and many more Interesting conversations as not many people want to talk about parasites :((. Xox

Stephen writes:

Dickson and Vincent,

By way of an introduction, I am a retired IT professional who took an undergraduate degree in biology many many years ago. TWIP, TWIV and TWIM are wonderful listening and I particularity enjoy the informal format of their broadcast.

Dickson, I am a person with Celiac, and I cannot help but wonder if Celiac evolved and survived because it might have had a survival
advantage for ridding the body of parasites which lodge in the small intestine and are hidden from the immune system. Ongoing regular
treatment by gluten would not be great for health and longevity but perhaps symptomatic or seasonal treatment by gluten containing grains
would confer some added benefit for primitive man. Could you please speculate on this possibility?

Thanks and keep up the great shows. I always look forward to listening to them on my not-an-ipod during my daily dog walk.

Kevin

Dorotha writes:

Dear Vincent and Dickson,

I am a huge fan of your show and I really appreciate the work that you do to make science more approachable. I especially like TWiP, because I think that parasitology is very underappreciated, not because it's any less exciting than other disciplines but possibly because of the 'yuck' reaction many people have when hearing the word 'parasite'. Your show is just another proof that parasitology can be interesting in a non-horrid way.

I guess you can apply Terence words "Homo sum, humani nihil a me alienum puto" (I am sure Dickson will enjoy translating it, as I noticed he's really into latin) even to parasites.

I have a question for you, that came to my mind when eating my garden-grown plums, which turned out to be more organic than I expected, with some worms enjoying their taste probably as much as I do: Are there any parasites that use worms (or in general insects) as vectors to get into their host via oral route?

Thanks for the great show!

Dorotha

Andrew writes:

You've probably already been notified on this, but the Coriolis effect has nothing to do with the way water spirals out a drain. On a body of water the size of a sink or even the Oculus the Coriolis effect is far too small to have a significant effect. The direction that water swirls in the toilet is determined by the shape of the water jets around the rim of the toilet.

http://www.snopes.com/science/coriolis.asp

Greg writes:

Dear TWiP Hosts,

Concerning your discussion near the beginning of TWiP #57, as a youngster I was fortunate to witness a demonstration of the Coriolis effect right at the equator (in Kenya). My family and I watched a man drain water out of a plastic bowl with a hole at the bottom. A few meters north of the equator, a matchstick floating in the water spun clockwise. Literally a few meters to the south, the experiment was repeated and it spun the other way. To my amazement, directly at the equator, the water drained straight out without any rotation!

Only much later, as a student of physics, did I learn that we had been deceived. The apparent acceleration caused by the Coriolis effect is of the order of the velocity of a moving object times the angular velocity of the Earth. Even if we generously give the draining water a velocity of a meter per second, this gives an acceleration that is a hundred thousand times smaller that the acceleration due to gravity. So other effects will easily determine which way water drains out of a bowl (or a toilet bowl for that matter). I speculate that the man doing the demonstrations at the "equator" would shake the bowl slightly, perhaps even unconsciously, to get the desired outcome.

The Coriolis force has a noticeable effect in phenomena occurring over longer timescales, accumulating the effect of the very small acceleration, such as weather patterns or the precession of a Foucault pendulum, or in phenomena with very large velocities, such as the trajectories of missiles.

I hope you will excuse this digression into the world of classical mechanics, and its applications to detecting fraud in the tourism industry.

Keep up the excellent work!
-Greg

TWiP 58 letters

Trudy writes:

Dear Vincent and Dickson,

Listening to TWiP on cyclosporiasis. Because I am all too aware of the possible contamination of many crops as a former public health nurse who worked in epidemiology for my state (Florida), I always wash my fruits and vegetables with a product called Fit. It may not be perfect in that pathogens are tenacious but I believe it reduces risk. (Could be hopeful thinking, I know.) Also, it does not alter the flavor of even delicate raspberries. I would be interested in what you think of this approach. http://www.tryfit.com I have no connection to this product whatsoever other than that of a consumer. I used to add a drop or two of liquid castile soap to fruits and vegetable wash water instead of Fit. Both approaches involve a short soak and gentle but thorough rinsing.

I was working in the Communicable disease clinics when Florida had a multi county outbreak in the 1990s. Our protocols allowed for distribution of stool culture kits then. Before I left my role, the onus was on the private sector. Unfortunately many people do not seek medical attention but treat with OTC remedies and many physicians do not test either. So the great unreported levels of both food and waterborne illnesses is a real challenge to any investigation.

Raspberries, blackberries, blueberries and strawberries were nestled in my cereal bowl this morning along with a bit of cereal! ;-) Is my approach biofilmsly?


As usual, your podcast is interesting, fun and informative. Happy that Dickson has been more available of late!

Warm and humid regards form Naples, Florida,

Trudy

Peter writes:

Dear TwiP team,

Interesting if rather gruesome report on the BBC news about a British woman who found that the headaches and pains she experienced on return from a holiday in Peru were due to an infestation of screw worm maggots in her ear.

http://www.bbc.co.uk/news/uk-england-derbyshire-23333284

Regards

Suzanne writes:

http://www.snopes.com/science/coriolis.asp

In case no one's told you yet.

Robin writes:

The Coriolis effect

It even affects bicycle wheel spoke screws.

http://sheldonbrown.com/symspoke.html

“Cyclists who regularly travel back and forth between the Northern and Southern hemispheres would be well advised to build up two rear wheels, one for use in each hemisphere...however, there's no need to have two front wheels, since the same front wheel will work in either hemisphere simply by reversing it in the fork!”

Food decontamination:

Back in the old country, decontamination of food items by a potassium permanganate solution was a standard recommendation.

Three stools negative in a row: how often?

cDc: Cult of the dead cow.

http://en.m.wikipedia.org/wiki/Cult_of_the_Dead_Cow

So what happens when the pupfish owl dies?

The Alternative Energy Matrix:

http://physics.ucsd.edu/do-the-math/2012/02/the-alternative-energy-matrix/

TWiP 57 letters

Anne writes:

I found TWIP just a week ago and feel I've found a home. I'm a pharmacist, usually on the night shift, and stay excited all night listening to you. Parasites have always been my hobby. In fact, I recently divorced one. His life cycle is unique. I get oddly thrilled when dispensing anti-parasitic drugs. Thought I was odd. Thanks for normalizing me. Annie

Renato writes:

Hello dear TWIP hosts!

Just in case you are not already exposed to this, I send you the web address for a recently launched worm-watching game:

http://www.wormwatchlab.org

It consists of video feeds of C. Elegans, which are being recorded automatically by tracking microscopes. As far as I understand it, the researchers want to measure the efficacy of the serotonin-regulated musculature of egg-laying for each worm, so recording when the eggs are layed is a vital piece of information.

This game is from the same guys that spawned Galaxy Zoo, where you classify galaxies, and Planet Four, where you classify terrain formations in Mars. Actually they have several interesting "scientific games", so I'd like to pick their project menu for this week:

https://www.zooniverse.org/projects

Also, there is something I'd like to ask Dixon. In TWIP 56 you and Vincent had a brief discussion about the name TWIP, why it uses the word "Parasitism" instead of "Parasitology". It has occurred to me sometimes that the "P" in a "TWIP" show name could also mean "Pathology". Whenever I think that, I wonder if all parasitism is a pathology - not necessarily a human pathology, but some living being's pathology. I then usually imagine that Dixon could argue that not all parasites cause harm to their hosts, and therefore parasitism is not completely within the scope of pathology. Is that the case?

Thank you and all your guests for the shows!

Regards,
Renato.

Oops, terribly sorry for misspelling your name, Dickson!

(I guess I always think of the Dixon from the "Mason & Dixon" line when I hear your name. By the way, the book by that name by Thomas Pynchon is an awesome read (well, all Pynchon books great, but M&D is arguably the best one so far)).

Chris writes:

On your last TWiP someone mentioned the Pandemic Board Game. I stumbled upon a YouTube video of it being played and explained by Wil Wheaton (the actor who started out as a teenager on Star Trek, and now shows up on various television programs):
http://www.youtube.com/watch?v=ytK1zDPPDhw

Apparently the person who starts is someone who had recently been sick, or had the worst disease. It turned out three of the players had caught H1N1 in 2009 at a gaming type convention in Seattle (link so you can understand what they mean by "Pax": http://prime.paxsite.com/ ), but one of them had suffered worse a few years before with a sequences of strep infections.

Enjoy. Just like I enjoyed learning about parasites in fish due to transporting them elsewhere.

Chris

(And I really hope that my two college age kids going to that same gaming convention don't get some kind of infection!)

Garren writes:

Hi all

I have a short bit of trivia to add to TWIP #56. You briefly discussed the topic of fish spawning and the salinity or not of the water in which the fish spawn. The question of a salty river was oh so very briefly brought up and dismissed. Well there does in fact exist a salt water river. I have been there and it is on the Island of Okinawa. The river is spring fed and the spring is so close to the ocean that the ocean water actually infiltrates the spring and it flows its extremely short length back to the ocean. It is something like 1-2km long. I have a picture burred around here somewhere but I know not where at the moment.

Cheers..

Robin writes:

http://amanwithaphd.wordpress.com/2013/07/08/what-genomic-data-tells-us-about-life-the-complexity-of-the-mealybug/

Joe writes:

Vince and Dickson,

Here is a follow up on your biofuels question. To make fuels from crops succeed we need a biotech breakthrough that I really thought someone would have done already. Basically we need a bug that eats cellulose and converts it back to sugar so you can ferment it. Personally, I think there is a Nobel Prize in it for the group that creates an e. coli strain that converts cellulose to sugars. Once you have that, then you can feed the farm animals the corn and run your tractor on the corn stalks! Or you could use hay or grass clips or wood chips or waste paper, whatever is available cheaply. Until we get that bug, ethanol from corn will just be a niche technology.

People will keep pushing to use corn crops or other high sugar crops to make fuel, but the economics are not good and the lost opportunity costs are too high. Look how the modest current efforts in the USA have pushed up food prices and still required government subsidies to be competitive. No doubt there is a listener out there with lots of arguments for how great ethanol from corn is but I don't see anything like the margin needed to make it a viable market changing crude oil substitute.

I will show my age and tell you that as a senior chemical engineering design project in 1980 at Purdue, we looked at how to convert crop waste materials (like corn stalks) into fuel and it wasn't pretty. The only real way to break down the cellulose was to grind it up and treat it with hot fuming sulfuric acid in big reactors. Fuming sulfuric is 98% concentrated acid that is saturated with sulfur trioxide gas, brute force chemistry for sure! As I remember, you could get pretty good conversion of the cellulose, but the ugly part was separating the good stuff from all the waste acid and the non reactive lignin. Once you got all the acid out of the good stuff, then you still had to ferment the sugars. It is not surprising that you don't see anybody running this process to make fuel! We need a biotech solution to break down the cellulose without all the mess. I think folks were looking at the microbes in termites' stomachs as a place to start., but I have not heard of any progress on this in several years.

I will add that biofuels are not the only option for our fuel supply. For the past 100 years, we have had repeated dramatic reports that we are about to run out of oil and yet it never seems to happen! I remember a particularly detailed one in Scientific American about 10-15 years ago with beautiful graphs and everything. Each time the trumpets of doom sound, some smart engineer or geologist comes up with a new way to extract more oil. I don't see any reason why this trend will suddenly stop this time, we still have lots of tar sands, deep oil, and shale oil that have not been touched. Please note that I am not expressing a political view on the social correctness of these options just the technical aspects. Even more impressive are the reported quantities of frozen methane hydrate clathrates on the ocean floor that would likely be fairly easy to extract. Some estimates are that there is more than 10 times the amount of energy stored there than in all the oil we have ever used. Obviously none of these fossil fuels address the CO2 generation concerns that many people have.

Wind, solar, hydro and even nuclear power all have their places and I hope their niches keep growing as the technology improves, but nothing comes close to competing with chemical energy as a cheap, portable, high density source of energy. One just needs to look at biology to see the truth of this; plants fix the suns energy into chemical forms that then cascade through the food chain ever evolving into more complex forms. How cool is that!

Thanks for helping me stretch my brain each week! Thus ends "This Week in Chemical Engineering"!

Warmest Regards,

Joe

Daniel writes:

Dear The Good Doctors!, I hope you are well!

I became fascinated with parasites at Uni when I was studying Freshwater and Marine Biology and took zoology and again relating to shifting global distributions of aquatic infectious organisms by climate change. I loved every aspect of parasitim but they were such small parts of my course I didn't think I could go into parasitology. I left college and went into aquaculture, listening to you all the while, which nudged me into returning to study. I'll be starting a masters in molecular parasitology at Glasgow Uni next year. I'm certain I wouldn't be, if not for you two and TWIP! I cannot express my gratitude in words for your effort and work making TWIP!

I love TWIP (et al.), I've been following it for years. However, I'm currently working at a remote pearl oyster farm in Australia (Beagle Bay, WA). As the podcast is over 50mb, my iPhone won't download it without a wifi connection. There is no wifi...

Is there anyway you can reduce the podcast file size? Without reducing the length of the show, of course!
File compression or something?

It's been months since I've had a TWIV fix and I'm starting to get the shakes!

Worm regards,
Daniel

TWiP 56 letters

Suzanne writes:

Your discussion about technology and fixing things here before we go out into space made me wonder if space exploration might turn out to be like investigative science. In the process of exploring space we might run across the means of fixing our problems here.

Robin writes:

Ecology and parasites

Just as "weeds" are plants that seemingly have no use for us, but interfere with our attempts to cultivate plants in controlled ecosystems set up by us, parasites are organisms that interfere with the controlled ecosystems that constitute organisms, but seemingly have no use in the limited perspective of human timescales.

The parasites may have substantial functions in shaping natural ecosystems, such as in controlling population overgrowth, helping in modulating immune systems (as in preventing autoimmune bowel disease in humans with intestinal parasites, and in building herd immunity - which was lacking in New World humans to Old World viruses, causing New World human populations to be wiped out on contact with Old World humans) and quite possibly other influences as yet unrecognised.

Extermination of wolves - perceived in the same light as parasites - caused an overgrowth of herbivores, altering plant populations and affecting the ecology of streams and rivers.

Parasites can have effects on human social structures, as when the Black Death so reduced serf populations that they brought an end to the structures of mediaeval serfdom in Europe.

We have been around for 200,000 years, and have had an understanding of the organisms we call parasites for but a couple of centuries. Our attempts to reshape natural ecosystems to what we see as our advantage in our timeframes may have unintended consequences on evolutionary and geological timescales.

Parasites and hosts are in a dynamic dance within ecosystems, a dance that contributes to shaping the ecosystems over various timescales of which we see but a few frames, and even a small part within each of those frames.

This is so well exemplified in virology, where we have only recently come to recognise that our very existence now depends on ancient viruses that melded into our genomes.

Parasite ecology:
http://parasiteecology.wordpress.com/

He also sent:

The Red Queen was Right

Blaine writes:

Hi there Twippies,

I saw this interesting link on the USDA website discussing the work of Eric Hoberg on the origins of tapeworms:
http://www.ars.usda.gov/is/ar/archive/may01/worms0501.htm?pf=1

I would love to hear you guys interview Eric or have a podcast discussing the origins/evolution of some of these parasites. I find it remarkable to think about these complex lifecycles and how these parasites require two or more hosts to survive. It just doesn't seem like a great strategy for survival (other than the fact that it does seem to work). This leads to a lot of questions about how or where these things ever came from regarding tapeworms that use domesticated animals as part of their lifecycles.

One more question that you may or may not have hinted on in your podcasts. Do parasites have parasites (or commensals)? There must be bacteria and viruses that infect or live on parasites. Is anyone studying them. Can you comment on this too?

Thanks,

Blaine
Fort McMurray, AB
Canada

John writes:

In TWiP 51 you speculated about the effect of wing muscle modifications on mating success in mosquitoes.

The subject of wingbeats and mating has been studied in the related family Chironomidae. Both families share an enlarged Johnston's organ
(hearing organ) in male antennae. Chironomidae are abundant and don't try to eat researchers, so they make better test subjects.

Males of most species form aerial mating swarms and listen for the wing beat frequency of females of the same species. I doubt females
listen for individual males, because they lack modified antennae. They may hear the swarm, and males could listen to each other to form into
a compact swarm.

A male of one of the larger lake-dwelling species might (metaphorically) say to a female:

"Meet me 5 meters over a contrasting dark object on the sandy beach at dusk when light has dropped below 50 lux. Beat your wings at 370 Hz
adjusted by 10 Hz per degree C of ambient air temperature above or below 20 C. I'll be waiting with a million of my friends."

The combination of swarm marker, altitude, and wing beat frequency is different for different species.

Reference:

Ogawa and Sato. 1993. Relationship between male acoustic response and female wingbeat frequency in a chironomid midge, Chironomus
yoshimatsui (Diptera : Chironomidae). Medical entomology and zoology. 44(4):355-360.

http://www.jsmez.gr.jp/simple/data/110003818262.html

To tie this back to parasitism, here is a picture I took of some ectoparasitic water mites on a midge (Chironomidae):
http://www.flickr.com/photos/31715949@N00/4616890577/

Joe writes:

Vince and Dick

As always I love your podcasts. You all made me laugh in TWIP episode 55 With Dick’s comment about the foreign nature of Chemical Engineers’ brains and Vince’s post modern nonsense about the evils of the internal combustion engine and denigrating it because it is was just so cheap.

Well let me take you on brief tour of how this Chem E’ brain sees the world.

The development of mechanical power to replace human and animal power is one of the single most important advances in human history. You may have heard of it, its called the Industrial Revolution. The rise of mechanical power is arguably the single biggest reason for the economic and moral decline of slavery as a viable social model on most of the planet. Slavery was rampant in the birthplace of democracy, ancient Greece, and not seen to be incompatible as it freed up the rich folks to have time to think deep thoughts. Mechanical power ranks right up there with the invention of writing, cities, mathematics and the scientific method as the most impactful events in our history that have enabled us to reach the incredible quality of life we have today. It has certainly had a much greater impact on the world than modern medicine or electronics both of which I value highly!.

The internal combustion engine in its various forms (2 stroke, 4 stroke, gas and diesel) is one of the single most successful inventions in history. It has beat out water power, steam power, coal fired boiler power or any other options in almost all applications with a few notable exceptions like centralized electricity generation. It is dependable, cheap, easy to repair, durable and scalable. This is the highest praise an engineer can give.

It has filled every available power generation niche in almost every conceivable human habitat and pushed its competitors to extinction. Here is a short list: weed whackers and leaf blowers, motorcycles, cars, buses, trucks, tractors, trains (diesel electric locomotives), ships, airplanes, portable generators, portable pumps and air compressors, One of the amazing things about the IC engine is that it has dominated applications where capital outlay is small with accompanying higher high operating costs (small engines) right on up to those larger applications where capital outlay is very high with relatively lower operating costs (locomotives, semi trucks and medium sized ships) Only at the very largest scales where turbine engines have an advantage do they lose out. Think E coli the size of an elephant for comparable biological example!

Imagine life in any large city without the IC engine. The quality of life drops dramatically. Public transit, food delivery, waste disposal, etc. all depend in the IC engine. I leave it to Dick to discuss the health and comfort impacts of all of us going back to horses. Don’t mind the flies and careful where you step!

Yes I know fuel cells and hybrids are so much cooler. Some day they may be one tenth as durable and successful as the IC engine. Some personal history will give some perspective, I started in a industrial R&D department in 1981 fresh out of college and I thought it was really great that about half of the R&D budget for this chemical company was going to developing membrane technology (AKA microporous separators) for use in electro chemical cells, which are essentially fuel cells running in reverse. We all saw the promise of the technology even then. They finally gave up years and many $$ later with little progress. The state of field has changed little since then and you can make the argument that this is a problem on the order of difficulty of our efforts to cure cancer. The devil is most certainly in the details. We engineers will keep working on these new technologies because that is how our brains are wired and there are some incredible advantages if we can ever make them work. But don’t disparage the IC engine until you can show me one of these new solutions going 200,000 miles over 10 years without several major rebuilds like so many old trucks and cars do ever day. Realize that the telling measure is that people only shocked when an IC engine breaks down much sooner.

If you stop and think about it, we all literally depend on IC engines on a daily basis in many ways. So the only real question is; “Have you hugged your engine today?”

All my best. You folks make my daily ride behind my IC engine a treat and are greatly appreciated!

Joe

PS. Yes machines are alive, just like viruses!

Joe
EH&S Manager

Amanda writes:

Hey guys!

Avid fan here, love all your podcasts, weather updates, and especially Dickson's digressions.

Just a teeny correction from TWiP #55. A listener (Jessie) picked the board game Pandemic. Unfortunately, you confused the board game with the flash internet game Pandemic 2. Minor, I know, but I don't want you, or any listeners, to miss out on the board game by thinking it's the same as the flash game. The two games, while equally awesome, are completely different.

In Pandemic 2 (The internet flash game and iPhone app) you build your pathogen and try to decimate the world through disease.

In the board game Pandemic, you work with 3 of your friends to eliminate 4 different diseases - developing cures and thwarting outbreaks. The game has a few levels of difficulty, and the expansion brings new elements like a mutated strain, a bioterrorist role, and even petri dishes to keep your game pieces in.

I highly recommend it! I was wary about the cooperative element, but it's a blast.

If I may, I'll submit the expansion as a listener pic: Pandemic: On The Brink
Also, for those that love Pandemic 2, there is an iPhone/iPad/iTouch app out there called Plague Inc that is very similar, but with a slightly nicer interface: Plague Inc

15 degrees Celsius and rainy here in Halifax, NS, Canada.

amanda.

Post-Doctoral Fellow
Canadian Center for Vaccinology
IWK Health Centre
Halifax, NS

Judith writes:

My husband discovered TWIM for me. It was love at first podcast. I am retired after a wonderful and exciting 40+ year career in Public Health in San Luis Obispo, CA.

I have tried to keep up with Internet articles but your podcasts bring me back into the latest happenings in such an entertaining manner. Having gone through all the TWIM's I am now into the TWIP's. I love all of the regulars & am amazed at the collective depth of knowledge.
I have a strong background in evolution and ecology and love when you put the pathogens in their "places" in the big picture.
Mycology was my greatest love ... would enjoy a "TWIF"! Maybe you could clone yourself Vincent!

Question: Why TWI Parasitism rather than This Week in Parasitology for uniformity ?

I just found this article ... http://www.sciencedaily.com/releases/2013/06/130627142549.htm. It is heartening that microbes are working hard to fix our messes.

Many thanks for all the hours of enlightenment! ... Judy

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