Click for more "Microbes After Hours" videos
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.
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.
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.
The American history mistakes start about 10 minutes into the episode.
Thanks for a great podcast!
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!!
Hi TWIP Twosome,
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
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
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?
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.
Fort McMurray, AB, Canada
PS. The Link to the NYTimes article is here:
In a local newspaper:
"Zoonotic research taking Framingham man to Peru"
Parasites may be sneakier than we surmise:
Transformation of malaria parasites by the spontaneous uptake and expression of DNA from human erythrocytes
We may have more baggage than we know:
Invasive Genes: Humans incorporate DNA from parasite
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.
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.
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.
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.
A student in virology, not so much in the coriolis effect.
Just got this link to an Australian Video via Digg in case it's of interest.
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.
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?
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.
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?
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
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.
'Tain't just mice that have adverse behavioural outcomes with Toxoplasma.
Should humans attacked or killed by big cats be checked for Toxoplasmosis?
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.
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.
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.
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.
Anyway, be well and keep TWiPping!
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.
Why can't Dr. Dickson TWIP via Skype when away?
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.
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,
Fort McMurray, AB
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.
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.
You have the best podcast on the web, hands down. I use your TWiP episodes in both my undergraduate and graduate classes.
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?
Allan Robbins, DIH, MPH
University of the Nations-Global Health
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).
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
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.
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!
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.
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!
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,
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.
The Coriolis effect
It even affects bicycle wheel spoke screws.
“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!”
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.
So what happens when the pupfish owl dies?
The Alternative Energy Matrix:
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
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:
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:
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!
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)).
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):
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.
(And I really hope that my two college age kids going to that same gaming convention don't get some kind of infection!)
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.
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"!
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!
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.
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.
He also sent:
Hi there Twippies,
I saw this interesting link on the USDA website discussing the work of Eric Hoberg on the origins of tapeworms:
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?
Fort McMurray, AB
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.
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.
To tie this back to parasitism, here is a picture I took of some ectoparasitic water mites on a midge (Chironomidae):
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!
PS. Yes machines are alive, just like viruses!
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.
Canadian Center for Vaccinology
IWK Health Centre
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
Hi Vince and Dick!
Has anyone volunteered to do transcripts for TWIP? I love this show, and I'd love to be able to contribute in some way. Forgive me if transcripts already exist and I'm just not finding them on the website. If no one is already working on this project, let me know and I would be happy to pitch in.
I am a nonscientist with a deep interest in biology, and the TWI shows are all definite favorites of mine. Thanks for making so much great content available.
P.S. - Have you ever played the boardgame Pandemic? As far as I know it's the only public health themed boardgame out there. It's challenging, and lots if fun. Call it a listener pick :)
Jessie in San Diego
First off, I want to say I recently discovered twiv and twip (and love them both). Thank you for such entertaining and informative podcasts.
1. Do you guys have any other shows?
2. I recently started going back to school, and started taking things I was actually interested in (namely biology). I had taken a genetics and a physiological psych course previously, but I had no idea how chemistry intensive basic bio courses were. My problem is, I'm absolutely useless at chemistry. While I seemed to score high grades on my exams, all of my labs were awful. What was supposed to be a crystal, turned out as brown sludge. What was supposed to change to bright orange, turned out dull yellow/green. And once my prof even had to rush my experiment to a hood because I had somehow made toxic fumes (even he was puzzled by that one). Is there any hope for me in any sort of public health or research related field, or should I just suck it up and go back to being a paper-pushing desk jockey?
Hello Dasher and Dancer Donder and Blitzen.. I mean Vince and Dixon!
I am a new listener and loving your podcast. I started with the renali worm and have been checking in each week and also going through your archives. Crazy fun! I have no idea what you are talking about half the time, but very impressed with the language and the fact that you both seem to know what you are talking about! I have a daughter in Microbiology and another one in Health Science and so i am hoping some knowledge will gradually seep in.. like osmosis, so that they will think I am smart.
I appreciate when you analyse and source the scientific words. Haha, and you were wondering if the mascatory secretory gel was something you buy at the drugstore! Funny! But anyway I always understand the parts about the weather and the kinds of weekends you have!
I have a query: Generally Is it correct that Dixon trusts that believes technology can solve our problems, but Vince on the other hand might feel we are moving further and further from our biological roots and this is what is causing a lot of our problems. For example D says mans job is to colonize space but V says he's too busy here on earth. D's solution to our food shortages is vertical farming a grand tech fix!
So, do you both also see this difference between yourselves? Or is that terribly simplistic? I would like to hear your thoughts about that.. if it doesn’t take you too far from your parasites.
Thanks so much for the show. veronica, from bc
Dear Dickson and Vincent,
I am a recently retired biomedical scientist, having worked my entire career in hospital labs, mainly in Microbiology, but in my latter years as a manager. I have been fascinated by parasitology since I was a student, however I do not have a formal qualification in the area, other than a few lectures as part of my training. It was therefore delighted to discover TWIP, and I have been listening avidly over the last few weeks – fascinating!
I was wondering if Dickson knows of any distance learning courses in General Parasitology – I would be very interested in following such a course.
Finally, just a small point, arising from an observation made by Dickson (TWIP 33) I think the rare human thorny headed worm Moniliformis moniliformis has the Cockroach Periplaneta americana as an intermediate host, rather than a paratenic host.
Perhaps, as I listen to the next podcasts, another TWIP aficionado has already pointed this out, if so, please ignore this.
looking forward to seeing many more new TWIP’s in the future
all the best
Peter from Cavan
In TWIP 54 there were a lot of pseudo apologies for Dicksons asides and I have to say no apologies are needed. I was unaware of the fascinating behavior of fig trees and their relationship to monkeys and bats. Please continue to wander off subject as the fancy strikes because it generally leads to me learning something I may have never come across any other way. I may be partial to this type of discourse as I ramble in both general discussions as well as emails so I will end this with a keep up the good work and go back to the task at hand of feeding this new calf who is waiting so patiently for me to finish up my email.
Sent from mobile device w/ a small keypad, forgive brevity and typos ; )
My name is Niall and I am a recent high school graduate working on a virology research project at Rocky Mountain Laboratories (part of the NIH/NIAID) in Hamilton, MT. Dickson may also be interested to know that I am an angler and my father is the local fisheries biologist working for the state. As such, I have heard a fair bit about whirling disease and would like to hear more if you haven't already done a show on it. Also, I have a quick question to ask you both. I will be attending Montana State University next year and majoring in microbiology. I am undecided as to what field of microbiology I will go into but have been intrigued by the following; virology, parasitology (especially of the Neglected Tropical Diseases), and the microbiome. I was just wondering if either of you had some tips or advice for an aspiring microbiologist. Anything helps.
Thank you both a bunch. I am a big fan of TWiV, TWiP, and TWiM and would love to hear what you have to say.
P.S. I just talked to my boss here at RML and apparently he knows Vince. His name is Marshall Bloom.
Tickborne Flavivirus Pathogenesis Section
Laboratory of Virology
Rocky Mountain Laboratories (NIH/NIAID)
Hi Vincent and Dickson,
I was listening to the new episode of TWiP (episode 52) and one of your listeners wrote in asking about tree parasites. While plant parasite is not my main field of research, I have written about one such parasite on the Parasite of the Day blog - the nematode Bursaphelenchus xylophilus which causes the tree disease known as Pine Wilt.
The basis for that post was actually a PLoS Pathogens paper on the genomic characteristics of that particular parasite.
In addition, there are also numerous insects, nematodes, and bacteria that can infect plant tissue and induce gall formation. I feel that
Dickson might be fond of those plant parasites because much like Trichinella spiralis, these organisms are capable of manipulating the
architecture of the host's tissue, forcing it to grow structures that both house and feed the parasites - much like T. spiralis with its
Dear doctors Racaniello and Despomier,
I just wanted to write in with a bit of praise. I have been a regular listener of TWIV for over a year now, and I'm just now catching up with both TWIM and TWIP. I have to say after having listened to the episode on hook worm and the remarkable back story given by Dickson about that organism in a historical context, that I am truly impressed. I spent ten years reading about history outside of school in my youth, and I must say that I am deeply impressed by both the depth and breadth of Dickson's knowledge.
Thank you both for a wonderful show and the hours and hours of edutainment.
They come out when it rains because they can. It's not so much that they avoid wet tunnels when it rains as they usually avoid dry ground. When the ground is wet they can come out so they do.
Hello twip hosts,
I just listened to TWIP 52 and all the emails had to do with you guys mentioning stopping TWIP. I just discovered TWIP last summer (2012), and I've caught up with all the episodes! I just wanted to let you guys know that TWIP has kept my mind constantly busy during half day hikes in the Pacific Northwest Cascades! I thoroughly enjoy the report Vincent and Dick have. I love the jokes. It is one of my favorite podcasts.
I was trained as a Chemist at San Diego State, so I have a special connection to TWIM, with the SDSU hosts that are often on there. I now live near Portland, Oregon and hike quite frequently.
I hope none of the TWI's die, and I thank you two for all your work and information you've given to thousands of people.
Hello Dr. Racaniello and Dr. Despommier!
I, like many, had a sinking feeling in my stomach when cancelling the show was proposed earlier. I was refreshed to hear this will not happen! Dr. Despommier, do you know the Komuniecki's at The University of Toledo? I had the opportunity to do some work in her lab (Patricia) working with Ascaris suum. Ah, the trips to the slaughterhouse.
If I may make a suggestion for a TWIP, TWIM, and TWIV: drugs. A review of antiparsitic agents and resistance mechanisms. Likewise antibiotics and resistance mechanisms (the New Delhi metallo-beta lactamase, cfr resistance, erm resistance, effluc pumps, gyrase mutations and everything TB has). What a show(s) that would be. TWIV, well i know there are not as many antivirals (for non-retroviral infections) but why not. Then again there is no shortage of TWIV episodes (sorry Dr. D).
Thank you both so much for all of the education and the history lessons. I am always captivated by Dr. D's stories.
Rick in Toledo OH, patiently waiting for spring to come
Dear Vincent and Dickson,
Attached is a letter which I think represents a sad state of affairs for parasitologists, epidemiologists, physicians and particularly for patients. It is a decision probably driven purely by cost. In the past year, I have treated a patient at this hospital with amoebic dysentery. Was this patient part of the 0.3 percent? Could you address the quoted statistic about the overwhelming giardia/cryptosporidium being found nationwide?
Spencer Kroll MD PhD
It is 50F and sunny today in Central Illinois, with plenty of flooding in low lying areas.
I would like to start by saying Thank You for the three TWiX podcasts. I enjoy listening to them during my commutes and while I am out walking. They are helping to keep my skills in Immuno/Micro/Etc while I am busy with my medical school studies in many other topics also.
I want to point out one clarification that applies to this weeks TWiP #53. You stated that a positive PPD indicated an active TB infection. It actually indicates that the patient has been infected with TB at some point. Most individuals that are PPD positive will not develop active TB unless if there is an issue with their nutrition or immune system.
The active disease is when there is clinical or radiographic evidence of the disease. Without either of these the patient at worst has a latent form of TB. This is important to know because latent TB is virtually non-transmissible.
It is also important to note that some patients with HIV and other immune disorders that effect the T cell population will not react appropriately to a PPD test due to a lack of T cells that cause the skin reaction.
SIU School of Medicine
PS I will be at the ASM conference in Denver. Do you know where and when you will be recording any TWiXs while you are there?
Hello TWIP team,
I love your family of shows, but while listening to TWiP 53, I noticed that Dickson used the word Eskimo. I hate to play politically-correct police, but Eskimo is now considered as fairly derogatory (at least in Canada and Greenland). The word, meaning "eaters of raw meat" by some accounts, has been replaced here by the word Inuit.
Just something to consider. Love the show!
Marcel in Canada
I bought crabs from a local grocery (Pathmarket ) and noticed these small black ovals the size of sesame seeds (image attached and compared to the size of a quarter) on one of the legs and I was hoping you could identify this and confirm its normal and an ectoparsite. I love the show.