Case guesses:

Jim writes:

Dear Twippers of the Mite Sarcoptic:

This poor teacher is mangy but her dog cannot be the cause. 

Humans have their own version of scabies and the Sarcoptic mites involved are very efficient at moving from one host to another.  By the time the teacher is symptomatic, scabies is probably well established in class. The mites can also easily be brought home from school to be introduced to parents and siblings. 

Fortunately, there are a number of topical treatments available as well as more powerful drugs that can be used if needed.  In addition, all clothing and bedding at home must be washed repeatedly to prevent a reinfection. 

It itches me to say it but this is a PTA Level Event

Take care,

Jim in Vancouver

Chelsea writes:


My first instinct was scabies. 

And then other words like Janeway lesions and Osler nodes also floated by but I don’t think they apply here. 

I believe a scabies infection Is supposed to be incredibly itchy and does go to the hands and between the fingers. They’re pretty contagious and spread by contact. I would assume she got it from the kids. I met a woman in clinic a long time ago who had a very similar story. 

I forgot to mention that scabies are a mite so that explains the allergen. 

And wow- the Wikipedia article is graaapphic in how it describes them. Or maybe I’m just imagining them burrowing into my skin. 

Permethrin cream should help. 

Interesting, scabies in dogs is mange. 

This is a lot shorter than my previous answer but I’m in a bit of a rush. Finally- I get to submit something after missing so many episodes. 

Thank you for making this awesome podcast! 


Kirsten writes:

Dx: Scabies mites.

(Crosses fingers as we would love to have the new Atlas in our lab)




Kirsten Snook, MSPH

Research Support 

Department of Pharmaceutical Sciences

Daniel K. Inouye School of Pharmacy

University of Hawai’i

Leta writes:

Hello TWiP-sters!!!

I wasn’t sure how to start off this email, so I’ll stick with the weather… It’s 79 degrees here in New Orleans with a humidity of 81%, so it feels like 85 degrees. It’s still hurricane season, so we have our daily thunderstorms that cranks up the humidity to 90%, which makes 77 degrees weather feel like 82 degrees. I’m sure you’ve heard stories from Dickson 😛

My diagnosis for TWiP case study 176 is Sarcoptes Scabiei or Scabies. My immediate answer when listening to this case studies was MITES, but I became skeptical after hearing she was still itchy and rash-y after her positive allergen test to dust mites. However, I quickly went back to my guess of mites when Dr. Griffin mentioned the “small, red lesions” on the webbing of her fingers. I wasn’t exactly sure which specific mites she was afflicted with as my memory failed to retain the details of my entomology class in grad school. Thankfully, PD6 is available for download as a PDF (I still want a signed copy of it though), and after a quick CTRL-F for mites, I got my answer! 

Just to be sure and answer my own curiosities, I checked to see if there was any literature on cross-reactivity between scabies and dust mite antibodies and there is!! Here’s the link to article for reference. The article’s introduction even mentions that outbreaks of scabies are reported in nursing homes, daycare facilities, as well as kindergartens, hostels and SCHOOLS!! 

As for my other curiosity, I wanted to check if the woman had a hypersensitivity or an adverse reaction to the medications. I can’t remember where I heard/learned this from, but I seem to recall in some cases of pruritus and skin rash, antihistamines and/or steroids can worsen it. I could have completely made that up in my head, so ignore this if I’m horribly mistaken. Either way, after re-listening to the case study, I noticed Dr. Griffin did not delineate between whether her rash/itchiness became worse, or simply, was still present and bothersome after taking the antihistamines and prednisone.

Her treatment was most likely a topical cream of permethrin, or lindane to be applied on the affected areas. (Also, kudos to her GP for taking the time to do a more thorough exam.)

Thank you for the time and effort y’all put into this podcast. It allows me to stay in touch with my tropical medicine knowledge as I currently work in clinical oncology (which is interesting, but not AS interesting as parasites). 

Just to share a fun little tidbit – the newest furry addition to my family, a stray 7-mo old puppy, Tonks’ fecal test results came back positive for hookworms!! Unfortunately, I didn’t run the fecal sample myself so I don’t know which species she has. However, I did find proglottids after digging through her poop and took some pictures/videos of the undulating tapeworm! As much as I feel bad for my poor pupper, I’m reveling in this real-life opportunity to talk and think about parasites again!

Sorry for the long email!! There’s so much I want to say! 


Leta Ko, MPH&TM

Parks writes:

Dear Drs of TWiP,

I am a long-time listener and a newcomer to bench work in parasitology, fortunate to be completing a postbac at the NIH, and excited to write you all for a first time.

After hearing your last episode I immediately focused in on two details of the case. First, that the patent is a teacher and second, that she had a rash that was experienced as systemic but upon closer examination showed lesions on her hands. 

Based on these criteria my best guess is an infection with the obligate parasitic mite, Sarcoptes scabiei. I think she has scabies! This appears to be supported by the antihistamine and steroid treatment not solving her malady, be bolstered by the allergic sensitivity to dust mites, spread readily between children, and require 5% permethrin topical treatment (and maybe ivermectin if things have progressed too far for topical treatment alone).

Either way, it looks like she will be making many trips to the wash and fold to take care of all the laundry and keep from reinfecting herself. 

Thank you all for making this fantastic and accessible podcast! 

My best, 


Katy-Jane writes:

Hi all,

This is my first time writing in, and I hope I do not make too much of a fool of myself! I am currently residing in Wausau, WI (north central part of the state), and am a livestock producer and instructor of agricultural sciences at the local technical college. I am also a British citizen, and have been fortunate enough to explore this wonderful world a little, including the suburbs of NYC and Long Island (although, admittedly, I prefer upstate…)

After doing a search on PD7 for parasitic diseases involving a skin rash, I ruled out many due to geographical unlikelihood, and narrowed it down to the following two:

Toxocariasis due to Toxocara canis: A disease primarily of young children with infections common in North America. However, it usually presents with fever, which was not mentioned in this case. It is also not spread person to person, which, although not specifically stated in the case study, was implied by the fact that several of the children in the class also presented with similar symptoms.

Which leads me to Scabies due to Sarcoptes scabiei: Presents with a generalized itchy rash, although on further inspection, mites themselves are found predominantly between the fingers and on the wrists. Aha! This matches our case study! It is also contagious, and the NY State Health Dept states that it is a common infectious disease and infestations can occur in child care centers. Upon further research, I found that people suffering from scabies will also react to antigens for dust mites, which could explain the allergist’s results for our patient. (Very interesting!) I therefore think that this is the most likely suspect in our case study. Treatment with permethrin – which, as a livestock producer, is something we usually have on hand!

I apologize if my answer is too long, and if I am wrong, well, I’ve now tried once and should probably try again! Thank you for giving me the opportunity to write in.

Chris writes:

Hello Twipsters,

It is a cold and windy 52 F(11C) here in Stonybrook Long island. Sorry for my absence, but now that my comprehensive exam is over I can get back into all the fantastic microbetv podcasts. Anywho onto this months guess, I would reckon that this  patient is suffering from scabies mites, nasty mites that can be extremely irritating and that like to live in between fingers. These mites can be transmitted person to person and the teacher in this case most likely caught them from their students. I already have a textbook ( proudly displayed in my office)  so no need to put me in the running for a book. 

Unfortunately, no parasite pictures or videos to share with you this month, but hopefully next month I will have some new ones.

Once again thanks for the great podcast as always (including the others such as TWIV) they have made processing hundreds of bivalves (and a few fish) for disease diagnostics much more interesting. I would love it if you brought on some more guests (similar to TWIV) to talk about their research as I know there are MANY parasitologists in the tristate area that would most likely love joining in on a conversation. Personally I would love to hear from some of the local wildlife parasitologists, but that’s just my two cents.

Lastly, to all the other listeners out there, I would highly recommend going to TWIP’s patreon! I, as a broke grad student, personally give a 5$ monthly pledge (less than a beer at a brewery). Vincent and his co-hosts have produced 1000s of hours of material, so giving a dollar or 5 a month is a small sacrifice compared to the time all the hosts have devoted to this educational program.

Warm regards,


Peter writes:

Greetings Dear Doctors of the Good Ship TWIP

I strongly suspect that the woman in the case reported in TWIP 176 has scabies, caused by an infestation of the mite Sarcoptes scabiei (only a small number of adult females required). This page on Everyday Health gave a good description of the symptoms and treatment (antihistamine and permethrin alongside decontaminating the house) I checked Parasitic Diseases 7 to ensure the web page’s accuracy of course.

The weather in Khartoum is hot and humid (I’ve been here for a weak teaching microbial pathogen bioinformatics with a focus on practical analysis of M. tuberculosis whole genome sequencing samples).

Karen writes:

Dear TWIP twio,

I’m pretty sure the answer to the case study is scabies, Sarcoptes scabiei. I find it very interesting that the rashly areas of the body are not necessarily where the actual mites are located. Crazy immune system!


Melissa writes:

Dear TWiP professors,

This is my first time attempting to crack a case, here goes.

I think our young school teacher may have scabies, which is caused by the arthropod Sarcoptes scabiei, also known as the itch mite. To venture slightly further, I’d guess that she has ordinary scabies rather than the Norwegian crusted scabies.

The clues that led me to this “hypothesis” are

1) red lesion on and between fingers, one of the tell-tale symptoms of a Sarcoptes scabiei  infection.

2) Some of her students also have these symptoms.  Therefore it must be relatively easy to transmit, again Sarcoptes scabiei fits the bill.

3) She is not immunocompromised, which tends to be a risk factor for crusted scabies.

Then after some (very brief) reading, more pieces of information in the case fits with Sarcoptes scabiei infection.

1) Sarcoptes scabiei is fairly common, therefore it’s plausible to find it in the outer boroughs of new york.

2) Her allergy test. Daniel never specified why her allergist thought dust mites may not be the cause of her symptoms, but perhaps her reaction to dust mites was not particularly strong. There is some evidence of IgE cross-reactivity between Sarcoptes scabiei and household dust mites.

Her treatment was likely something along the lines of 5% permethrin cream. The CDC website for health professionals outline a couple of different treatment options.

Additionally, the local health department should be notified, as there is community spread of the parasite. People who’s been in close contact should be tested and treated for scabies. Additionally, cloth materials in the classroom, as well as anything that has been in contact with either her or her students, should be laundered or sealed in airtight plastic bags for at least 3 days to make sure any Sarcoptes scabiei in the environment is killed off.

Wow this email turned out MUCH longer than I anticipated.

Thank you all, for this great podcast that 100% makes my time in the lab much more fun.


from a (relatively) sunny Toronto at an acceptable 12 degrees celsius.


1) The CDC website: Accessed October 25, 2019

2) Walton, S. F., Pizzutto, S., Slender, A., Viberg, L., Holt, D., Hales, B. J., … O’Hehir, R. (2010). Increased allergic immune response to Sarcoptes scabiei antigens in crusted versus ordinary scabies. Clinical and vaccine immunology : CVI, 17(9), 1428–1438. doi:10.1128/CVI.00195-10

3) Fuller, L. C. (2013). Epidemiology of scabies. Curr opin infect dis, 26(2), 123-6. doi: 10.1097/QCO.0b013e32835eb851.

Kevin writes:

A scabrous education

Proverb: Tis better than riches to scratch where it itches.

Quote: None but kings and princes should have the itch for the sensation of scratching is so delightful.

-James I

Some things in medicine never change, demonstrated by consulting Chapter XX of Tilbury Fox’s 1875 Dermatology book, which describes our TWiP 176 case to a tee:

This is a most important disease to be well acquainted with. Whilst its frequency is extreme, its features, happily, are very definite, and its facility of cure great. But mistakes are very frequently made in its diagnosis.”

Dr Griffin’s case does not mention if our patient is married, and if so, for how long. This could prompt the question ‘Does our patient have ‘The Seven Year Itch?’; that metaphorical pruritis that occurs consequent to the longueurs that invariably accompany seven years of marriage.

More to the point, PD7 contains a kind of vitruvian woman type of illustration that depicts body regions favored by the itch mite. It is a dead giveaway for TWiP 176. 

The causative organism in this case was named acarus humanus subcutaneus by Linneaus in 1747. It is now called Sarcoptes scabiei var. hominis.

I will dutifully offer a differential diagnosis. By coincidence, the NYT Sunday magazine “Diagnosis” column (10/16/2019) presents the case of an itchy man. Scabies is mentioned but the culprit was toxocara. We can add other nematodes to the DDX of parasitical itch: e.g. strongyloides and cutaneous larval migrans from hookworm infection. A return to TWiP 157 can help augment our differential by considering bedbug bites, flea bites, or other incidental mite exposures such as Tyrophagus, Trixacarus, and Glyciphagus. However the daycare setting, typical symptoms and very characteristic lesion/rash distribution in our 176 case points unequivocally to scabies.

Relevant to our case is the fact that skin tests may not differentiate between the dust mite (Dermatophagoides farinae) and S. scabiei. Our patient’s trip to the allergist resulted in a delay in diagnosis and maybe threw a bit of gasoline on the fire via the administration of steroids (mother’s milk to a peripatetic mite). Bagholi et al in a 2014 case report (strikingly similar to TWiP 176) reminds us that “It is important that allergists be aware of the antigenic cross-reactivity between house dust and scabies mites and its implications.” 

A few other relevant facts. Typical scabies usually spares the head and face. Favored sites of rash/infection are hands, wrists and elbows. Other areas that are enjoyed: genitals, feet, buttocks, axillae, breasts and waistline. The Arilan et al 2017 reference in the Endnotes exhaustively reviews the biology, genetics and immunology of this pest, as well as discussing the development of diagnostic blood tests and vaccines. Like its fellow degrader of social status the bedbug, these mites transmit no known disease. Fomites are generally not considered as significant in scabies transmission, the classic studies being Mellanby’s 1940s human experiments. Arilan states: “Thus, in homes, schools and nursing homes, extensive cleaning, disinfection and laundering should not be required to eliminate scabies mites in dry climates. Leaving a bed, bedroom, bedding and clothing isolated for 48 h at room temperature should result in the death of scabies mites.”  Patients should be given reassurance and education to prevent development of delusional parasitosis. 

The WHO classifies scabies as a neglected tropical disease and has been involved in mass drug administration trials. Scabies can affect 5-10% of children in low resource nations, resulting in misery, degradation of education, and other medical sequelae such as impetigo and post-streptococcal glomerulonephritis. Typical scabies must be differentiated from scabies in the immunosuppressed and crusted or ‘Norweigan scabies’, both of which require a separate discussion. 

Treatment is well described in the CDC and WHO websites. It is interesting to note that the ancient remedy of 5-10% sulfur in vaseline is still a potential cure and is safe to use in infants. It’s a remedy you could actually make at home. Note that ivermectin is not FDA approved for scabies but is CDC recommended for treatment failures and crusted scabies.

Thanks for scratching an itch in my mind.

ENDNOTES (in no particular order)


Yes, the word scabies occurs in the bible:

Leviticus 13:6

VULGATE 6: et die septimo contemplabitur si obscurior fuerit lepra et non creverit in cute mundabit eum quia scabies est lavabitque homo vestimenta sua et mundus erit 

KJV 6: And the priest shall look on him again the seventh day: and, behold, if the plague be somewhat dark, and the plague spread not in the skin, the priest shall pronounce him clean: it is but a scab: and he shall wash his clothes, and be clean.

Oxford English Dictionary: scabies…in the obsolete sense: “a skin disease characterized by a scabby or scaly eruption” 

Latin: scaběre- to scratch or scrape

Sarcoptes etymology:modern Latin (Latreille 1804), irregularly < Greek σαρκ-, σάρξ flesh + κόπτειν to cut.

French (needed to ‘get’ the coinicdence mentioned in A Terminal Curiosity (below): gale=scabie (maladie de la peau)

A related and delightful word: scabrous.

Various Old Textbook descriptions:

Skin Diseases: Their Description, Pathology, Diagnosis, and Treatment Tilbury Fox, New York:William Wood 1875 Chapter XX, Parasitic Diseases

Contains such lyrical antiquated medical terms as phthiriasis and bug eruption.

Fox’s prose gets very colorful: “On a healthy and clean skin no great amount of mischief follows; the acari however, delight in dirt, and run riot as it were on unwholesome surfaces.”

Fox again:

“Now the acari prefer the hands of adults and the thin skin between the fingers ; and in these parts the disease is first seen, as solitary vesicles, many of which have the acarian furrow running away from them; then the disease travels to the front of the forearm, the belly, thighs, and especially the upper line of the penis.”

Foxs’ therapy employs a scorched earth policy regarding the scaling and crusting: “These crusts may be softened up by turpentine or caustic soda or potash.” (note: caustic soda is sodium hydroxide, commonly known as lye. Potash here likely referring to potassium hydroxide)

Fox is emphatic that the rash spares the face and head, and emphasizes this as a diagnostic clue.

Essentials of Diseases of the Skin, HENRY W. STEELWAGON, M.D., PH.D. 1909 

Steelwagon on diagnosis: State the diagnostic features of scabies: The burrows, the peculiar distribution and the multiformity of the eruption, the progressive development, and usually a history of contagion. Upon what parts are burrows most commonly to be found? In the interdigital spaces, on the flexor surfaces of the wrist, about the mammae in the female, and on the shaft of the penis in the male.

Hand-book of Skin Diseases for Students and Practitioners, Thomas Hillier, 1865.

“The existence of vesicles between the fingers with small papules on the anterior aspect of the forearm, and a few cracks on the front of the wrist, may be taken as almost absolute proof of scabies…

Sulphur is the best remedy for scabies…at the Hospital St Louis in Paris, the disease is now usually cured in two hours…”

The Cyclopaedia of Practical Medicine: Comprising Treatises on the Nature and Treatment of Disease, Materia Medica and Therapeutics, Medical Jurisprudence, Etc. Etc. Jau – Sma, Volume 3 Sherwood, Gilbert, and Piper, 1834

“There is scarcely any disease compromising the general health in so trivial a degree in which it may be more important to the reputation of the practitioner to be able to deliver a categorical diagnosis than in scabies.”  This Cyclopaedia’s entry on scabies contains a very lively history of scabies from the 12th Century onward, which strains credibility as to how such a humble disease could generate heated controversy.

A Compendious Medical Dictionary Containing an Explanation of the Terms By Robert Hooper 1801. 

Entry under psora. “The itch”. Gk ywra . “…order dialyses of Cullen”  “…appearing first on the wrists and between the fingers in small pustules with watery heads. It is contagious.”

The definitive Demodex folliculorum article (open access)–

Demodex folliculorum blepharitis, T O Coston,Trans Am Ophthalmol Soc. 1967; 65: 361–392. 

Pyemotes, the Mysterious Itch Mite, Scott E. Glosner et al. US Pharm. 2008;33(5):59-64.

Good examination of the differential diagnosis of mites that cause itching in humans. In this case report we see the postulated arboreal transmission cycle from oak tree to human!

Scabies history in a nutshell:   in fact this entire website is an excellent student produced online resource for parasite biology and history…. []

Gale’s original 54 page 1812 monograph:

Scabies in animals and humans: history, evolutionary perspectives, and modern clinical management, Russell Currier et al, Article in Annals of the New York Academy of Sciences · August 2011

Mellanby’s WW2 studies concluding that fomites play no significant role in scabies transmission. Scabies has been observed to occur in 15 year cycles…one of the more recent ones was 1965-1980. Sexual transmission is well described, but non-sexual close contact is also very important. Infections in immunocompetent adults- average mite burden approx. 10 female mites…

Mellanby on Scabies, J. A. Savin, Clinical and Experimental Dermatology, 27, 86–87

Very charming article, part of a series ‘A paper that changed clinical practice.’

A review of Sarcoptes scabiei: past, present and future, Larry G. Arlian & Marjorie S. Morgan

Parasites & Vectors volume 10, Article number: 297 (2017) 

some basic biology:  **In the historic published literature, it is suggested that females produce 40–50 or more eggs over a life span of 26–40 days

**Regarding infectivity: quote=”Thus, in homes, schools and nursing homes, extensive cleaning, disinfection and laundering should not be required to eliminate scabies mites in dry climates. Leaving a bed, bedroom, bedding and clothing isolated for 48 h at room temperature should result in the death of scabies mites. In dry climates (< 50% RH) mites likely”

Dermatophagoides and Sarcoptes cross-reactivity in clinical allergy skin testing:

-Positive house dust mite skin test in a nonatopic patient with scabies. Bajoghli AA, et al. Ann Allergy Asthma Immunol. 2014 Dec;113(6):667. doi: 10.1016/j.anai.2014.08.023.

The authors conclude this case report with the caveat:

It is important that allergists be aware of the antigenic cross-reactivity between house dust and scabies mites and its implications. The case report reminds the allergist of this possibility.

Terminal Curiosities

Scabies in Cattle, Richard West Hickman U.S. Department of Agriculture, 1902 – 24 pages   Great illustrations on how to construct cattle dip stations. Formulae for elimination of Psoroptes communis and Chorioptes symbiotes. (Flowers of sulphur and unslaked lime…) 

Cutaneous mite infestations in domestic animals are a huge problem. 

Above: Reuben Freidman’s bookplate. “Dr. Friedman’s specialty was scabies an itchy affliction caused by the creature on his bookplate. Friedman wrote “The Emperor’s Itch, The Legend Concerning Napoleon’s Affliction with Scabies. Also wrote “The Story of Scabies” New York:Froben 1947.


Part of this news story, I fear, can be classified as fake news. 

Fear of contagion By Lydia Esparra | December 5, 2018 at 9:32 PM EST – Updated December 6 at 3:36 AM 

CLEVELAND, OH (WOIO) – Summit Academy will be closed on Thursday and Friday after scabies were discovered at the school.  They first reported the outbreak at the end of last week and the school was thoroughly cleaned over the weekend. It wasn’t enough to contain the spread. Kevin Brennan of Cuyahoga County board of health warns that scabies is highly contagious “They get on your skin and the burrow, and once they make that initial point of entry, then the female will come in and she’ll burrow or tunnel,” Brennan said. The female will then lay eggs under the skin, which leads to an unbearable rash that spreads every time it’s touched or scratched.

The mites can only be transferred with direct contact. Children and nursing home residents are the most at-risk populations.

Here’s what to do if your or your child has scabies:

  • Seek treatment immediately—most cases with a cream and antibiotics. 
  • Wash and dry all bedding, clothing and towels that have made contact with the afflicted.  
  • If items can’t be washed or dry-cleaned immediately, place them in plastic bag for several days to a week.  

Once medical treatment begins, scabies the mites will die in two to three days. If left untreated, they will continue to feed off skin and spread. Brennan says that’s why you need to take immediate action.“It’s very easy to treat. It’s very easy to get rid of—it’s just a shock oh my gosh what’s going on with me?”Brennan also said that the health department didn’t recommend the school closing—they made the decision on their own.Summit Academy will reopen on Monday.

Annals of Cartoons- Focus on Pruritic Persons

TWiP 176, featuring an educator suffering with a malady in previous centuries known as the itch, stimulated me to examine two cartoon characters, both with the name ‘Itchy’. My faulty memory has for some time now been recalling a character named ‘Itchy Brother’, whom I wrongly assigned to the comic world of Dick Tracy. I now realize that Itchy Brother was from the 1960s-era television cartoon ‘King Leonardo and His Short Subjects”. The Dick Tracy villian was named ‘Itchy’, short for Itchell Oliver, a character introduced in 1945; he was afflicted with an intractable itch due to some kind of skin ailment. It is not inconceivable that both of these cartoon characters were afflicted with scabies. Itchy had a brother named ‘Twitchy’, who may be discussed if later episodes require his services. 

Source for the info on itchy brother:

Scabies History, more than you need to know, with Svensk nationalist flavor

A strange debate (see Thyressen abstract below), not in small part due to the ‘nominative determinism’ which pairs up the name of Jean Chrysanthe Galés with the French word for scabies/mange which is gale. There seems to be a lot of national pride tied up in the primacy of the discovery of the etiology of scabies. 

Sydsven Medicinhist Sallsk Arsskr. 1994;31:79-90.

[The remarkable debate during the beginning of the nineteenth century concerning the aetiology of scabies].

[Article in Swedish]

Thyresson N.


The scabies mite (acarus or sarcoptes scabiei) was known already to Aristoteles, to the Arabic medicine during the early and to European physicians as well as laymen during the later Middle Ages, depicted in 1687 by Bonomo in Italy and by Schwiebe in Germany during the beginning of the eighteenth century. Later in the middle of the century three pupils to Linnaeus in their doctor’s theses stated that the scabies mite (Acarus humanus subcutaneus) was the cause of scabies. The best pictures of the scabies-mite as well as of the flour- and cheese-mite was given by the Swedish entomologist Charles de Geer in 1778. In spite of all these facts the real aetiology of scabies seemed to be unknown in France and in most parts of Europe. This was probably due to the fact that no one had learned the rather simple method to extract the mite from the skin with a needle and thereby verify its existence. In the beginning of the twentieth century scabies was a real problem for the health authorities. In Paris l’Académie de Médecine even offered a reward to the person who could solve the enigma of the itch. Jean Chrysanthe Galés was the pharmacist at l’Hôpital St. Louis, the famous skin hospital in Paris, where at this time about 65 percent of the beds were occupied by patients suffering from scabies. Galés also studied medicine and wanted to write a doctor’s thesis. As the theme of a dissertation he was given the cause of the itch. In 1812 he published his thesis (“Essai sur la Gale”) including a plate with sketches of mites that he claimed to have extracted from vesicules on the skin of his scabies patients. His findings could not be verified by other investigators. Galés however refused to take part in any control experiments and left the hospital. The debate concerning the supposed cause of the itch continued for two decades both inside and outside the hospital. F.C. Raspail, a famous natural scientist, was interested. After having studied the literature and especially the drawings by de Geer he was convinced that the mites depicted by Galés were similar to de Geers’ flour-and cheese mite and that they had no resemblence to his picture of scabies-mite. In a control experiment Raspail could show how Galés had cheated by contaminating his slide with cheese-mites. However, a Corsican student at l’Hôpital St. Louis named S.F. Renucci knew the answer to the riddle. He had long ago been taught by peasant women of his home island how to extract the mite and he could now show the method to the doctors at l’Hôpital St. Louis. this was on August 13 in 1834, which usually in the literature is looked upon as the day when the discovery of the aethiology of scabies was made. Maybe we have a different view in Sweden.

Ted writes:

Taking a stab at an easy one here. 

This sounds like scabies, especially given the location of the lesions between the finger webs, and the evidence of contacts with similar symptoms. She likely received permethrin as treatment. Ivermectin is a choice for severe infection, but given that she does not have evidence of “norwegian scabies,” (ie crusting lesions on her extremities, severe rash over all extremities” she likely would not benefit from systemic treatment. A presentation such as that would prompt me to consider further work up for a cause of an immunocompromised state.  

Hopefully the children in her classroom are also being treated as well, as she would be at high risk of reinfection. 

Working my way through residency, but still very much enjoy the reminders and science available through TWIP. Carry on gentlemen. 

(also I already have a copy of PD6, so you can keep me out of the running for a copy)


Ted Rader, MD MS

PGY2 Internal Medicine, VCUHS

Adam writes:


My guess for case 176 is scabies.

Also, I liked it better when TWiP was biweekly – more TWiP is better:)


Adam Oscarson,

Halmstad, Sweden

Carlos writes:

Hi TWIP team!

It sounds like the patient from case 176 has scabies because of the intertriginous, itchy, and what sounds like inflamed papules. She could have acquired this illness from her contact with children. Hopefully, no one else acquired scabies from close contact. Possible treatments include permethrin cream from head to toe or a single dose of ivermectin.

Looking forward to the next episode!

Caitlin writes:

Dear TWiPster Gods,

The teacher has scabies – the “between the fingers” is a dead giveaway. She probably got it from the children she teaches, as kids spread everything. Treatment: topical permethrin cream, or ivermectin.

I don’t have anything clever, so here is a historical anecdote: according to legend, the Chinese warlord Yuan Shao once refused to go to war because his youngest son had scabies, and he was too worried about the boy’s health to leave. Supposedly, this missed opportunity was the beginning of his doom. At the time, scabies would have been treated with herbal mixtures that were apparently fairly effective. I’ll still take the ivermectin.

Caitlin, in Seattle, where it’s getting chilly by American standards.

Mae writes:

Dear Doctors, 

Long time listener, but first time having a go at guessing a case study. Hopefully I am not too late for this months’ case!

When hearing this case, I immediately thought of scabies, or Sarcoptes scabiei. I reached this conclusion thanks to the useful mention of the lesions between and on the fingers. I then went to PD7 and used everyone’s best friend ‘control F’ to search for ‘hands’, where I found none other than scabies. Waking up in the morning with a rash and itching is also characteristic of scabies, and most find itching is worse in the night. Her general practitioner likely would have taken a skin scraping to confirm.

If this is the case, I would expect the treatment to be lidane, or permethrin administered in a cream. Hopefully the children at school are also followed up, as well as their families, seeing as it spreads easily.

Thanks for putting together such a great show, it has gotten me through many PCR runs in the lab this year looking for Strongyloides stercoralis as my honours research,


Mae, from a currently quite hot Adelaide, Australia.

Mae White 

BArch, BSc 

Honours Student in Environmental Health

Flinders University

Ben writes:

Dear Plasmodium falTWiParum,

It seems my email from last episode got lost but that’s okay because my diagnosis was wrong J

Sounds like the woman from TWiP # 176 along with some of the children in her classes are suffering from scabies! Treatment would need to be extended to all affected children and possibly other children in the same classrooms to ensure the outbreak comes to an end. I’ve always found it curious how so many of our behavioural and hygiene habits exist to avoid ectoparasites, yet public awareness of ectoparasites, with the exception of head lice, is extremely poor.

Something that might be useful for a lot of TWiP listeners is the newly launched Parasite Slack. A link to the parasite slack can be found on the parasite slack Twitter. Essentially it is a parasitology message board, with some specific parasite channels, along with channels for job advertisements, protocols in parasitology and parasitology resources. I of course made sure to mention Parasitic Diseases 7th edition and TWiP in the resource section J

It’s currently sunny and 37oC in Adelaide, South Australia following on from a beautiful 30oC during the Malaria in Melbourne conference earlier in the week! 

Newton may have seen further by standing on the shoulders of giants, but Toxoplasma took the giants closer what it wanted to see. 

Keep up all the wonderful work!



Ben Liffner

PhD Candidate – Malaria Biology Lab (Wilson Lab)

Research Centre for Infectious Diseases

School of Biological Sciences

The University of Adelaide

Sophia writes:

Hello doctors! 

and a happy (belated) birthday to Dr. Despommier. I hope this email makes it before the new twip is aired. My guess for this case is scabies.  I am keeping this short as I think you’ll get loads of email. But I would like to hear more about how this teacher got infected. I don’t think the Babesia case was easy by the way. Maybe I am doing something wrong.

all the best to you from Greece


ps you used to talk about the weather in this podcast (and other things). I wouldn’t mind if you went back to doing it again…..Just a thought

WesternU Global Health Track Students: Dana, Steven, and Chris write:

Hello TWiP professors, 

We believe the most likely diagnosis to be scabies due to the parasite Sarcoptes scabiei given the characteristic lesions between her fingers and the fact that some of her students have similar symptoms. The therapeutic used could be a topical scabicide such as 5% permethrin. 


WesternU Global Health Track Students: Dana, Steven, and Chris

Andrew writes:

Gidday again from Pongaroa, New Zealand,

{No book won yet – but ever hopeful}

The weather here is decidedly spring-like with 21°C and clear skies except for some cirrus and a UV index of 9.

A good day for sitting in shade and solving the puzzle of the young teacher with the rash.

My diagnosis: it “mite” be scabies (Sarcoptes scabiei). 

For me the clue that set me on that track was the lesions between the fingers. I had heard of this before somewhere – probably when my daughter was going to kindergarten and I, like most parents, were constantly and almost obsessively looking for signs of parasites. I was not aware that it could cause a “head to toe” rash and the images of crusted scabies are the stuff of horror films. 

The insightful question came from Vincent who asked about the teacher’s family as treatment of the whole family would be advisable and this critter is very contagious with skin to skin contact. 

An interesting fact about Pongaroa. It is the birth place of Maurice Wilkins who got The Nobel Prize in Physiology or Medicine 1962 for along with James Watson and Francis Crick. A tiny rural town that is quite proud of his achievement.




Kevin writes:


This topic is beginning to defeat me. I quote J Gordon Thomson: “The author regrets that he could not furnish a comprehensive review of all the anomalies, fallacies and puzzles which might be encountered in man.”

A discussion on TWiP 175 (time signature 127.42 mins.) concerned one listener’s obscure photograph of a 40 centimeter worm ostensibly retrieved from his own feces five years ago. Unfortunately, this poor quality photo made organism identification impossible. In the podcast, Dr Despommier suspected that the patient’s fecal discovery may have been a ‘mucus cast’ and speculated that the object in question may have been an ‘artifact.’ 

That discussion put me in mind of the whole subject of pseudoparasitism. a topic that was touched upon in TWiP158. I am also goaded to explore this topic due to the vague similarity of the prefixes pseudo- and quasi-, having noted Dr. Racaniello’s delight in the latter term. First, to dispose of the etymologies: The Greek pseudos means falsity or falsehood (compare quasi, which means resembling or simulating). 

Many of the articles that I reviewed do not specifically define a pseudo-parasite, seeming to take the term at face value. The University of Pennsylvania veterinary parasitology department defines it as “a parasite which is found in the feces of a host which it was not infecting, rather it just passed through after the animal ate the original host or material contaminated with the eggs or cysts.” This definition unfortunately omits findings in blood smears, urine, sputum etc. The Oxford English Dictionary defines pseudoparasite thus: “an organism whose presence within another is interpreted as parasitic but which is only present by accident; (formerly also) a hemiparasite, an organism apparently but not strictly parasitic, such as an epiphyte or saprophyte (obsolete).” This definition has the merit of not limiting the faker to the feces. Of course there will be overlap with the term artifact, though strictly speaking an artifact usually refers to phenomenon that result from tissue processing (example, a platelet superimposed on a red cell, simulating an intracellular inclusion).

The marginalization of the term pseudoparasite is evidenced by its omission as a MeSH heading (Medical Subject Heading) in the PubMed database. In the articles that I reviewed, the term remains undefined and seems to belong to the category of “I know it when I see it.” Various permutations of the word pseudoparasite in PubMed’s advanced search indices shows that it is infrequently used. PD6 and PD7 do not index or mention the word pseudoparasite.

For me, the most recent and egregious example of pseudoparasitism was what I like to call the “Loyola Worm”, or as the debunking 1983 Lancet article dubbed it: “The Worm that Wasn’t.” In 1983 Lueck et al, working at the Loyola Stritch School of Medicine near Chicago, published a paper in The American Journal of Obstretics and Gynecology more or less claiming to have discovered the etiology of toxemia of pregnancy, which they laid at the feet of a previously undescribed worm, christened Hydatoxi lualba. This whole unfortunate affair was quickly discredited by multiple authors, providing an object lesson in the hazards of rushing to publication as well as the folly of not employing experienced parasitologists as collaborators. Strictly speaking this spurious finding was an artifact, though the deluded authors saw fit to elevate it to the status of a pseudoparasite. 

A word on mucus casts. 

Colmer-Hamood’s review on fecal microscopy is one of the few references via PubMed that I could find which mentioned mucus casts. She states that casts can be “often seen in persons whose food intake includes bulk-producing food fiber such as psyllium husk, can be mistaken for adult Ascaris species.” Don’t miss the Endnote reference outlining a gall bladder mucus plug impersonating an ascarid. A general Google image search turns up many interesting photographs of mucus casts, with some fantastic photographs of mucus casts on ‘ParasiteGal’s’ blog (REF). These photos show the plausibility of mistaking expelled intestinal slime for a worm; Dr. Despommier knows what he’s talkin’ about. Though relevant to this topic, time and energy do not permit a discussion of the recent phenomenon “rope worm or ropeworm”, I refer you to the Wikipedia entry on the subject. 

I’m trying to close…I will only mention a few spurious, quasi, pseudo-findings that could measure up to our correspondent’s 40 centimeter specimen: perhaps a horsehair worm (nematomorpha)?? or maybe a giant terresterial turbellarian??. I’m not making this stuff up! It gets weirder. See the rambling Endnotes.

Thanks for your patience.


quasi-parasite and pseudo parasite NOT in the MeSH heading database

PubMed Advanced search index entries:(number of occurances in parentheses)

pseudoparasite (15)

pseudoparasites (21)

pseudoparasitism (26)

pseudo parasites (3)

pseudo parasitism (8)

Brood parasitism in the sand martin, Riparia riparia: evidence for two parasitic strategies in a colonial passerine. Alves MAS1, Bryant DM. Anim Behav. 1998 Dec;56(6):1323-1331.

The term quasiparasitism appears here. Only one hit and only one MeSH heading in advanced search

quasi-parasitism does appear in the ornithological literature

Quasiparasitism (QP) is a third type of alternative mating strategy, where a female lays an egg in another female’s nest and that egg is fertilised by the male partner at the parasitised nest.

giant hammerhead flatworm can reach 40 cm (almost 16 inches)

female ascaris can reach 40 cm ( › parasites › ParaSites2005 › Ascaris › JLora_ParaSite)

Gallbladder Mucus Plug Mimicking Ascaris Worm: An Ambiguous Cause of Biliary Colic.

Termos, S et al, Case Rep Surg. 2017;2017:7167934. doi: 10.1155/2017/7167934. Epub 2017 Nov 26. OPEN ACCESS

Rope Worms: C’est la Merde , Harriet Hall on May 27, 2014 

excellent photographs of the ‘ropeworms’

must guard against the temptation to classify these cases as delusions. —-from Manual of Tropical Medicine, Castellani

“…it is almost axiomatic that every beginner has to blunder at least once over an air bubble and over an oil globule…” J Gordon Thompson 1926. Quote below from Pseudoparasites in the Faeces of Man, J. GORDON THOMSON, Proc R Soc Med. 1926;19(Sect Trop Dis Parasitol):14-8.

Provocative titles: Emrys-Roberts 1914 paper, Banana Debris in Faeces Simulating Tapeworm Segments

Regrettably I could not locate this gem.

Terrestrial turbellarians (Tricladida: Bipaliidae) as pseudoparasites of man., Walton BC, Yokogawa M. J Parasitol.1972 Jun;58(3):444-6.

This is a report of two cases. Nice hand drawn illustration of Bipalium fuscatum

Quotables from Walton et al:

“Terresterial turbellarians are nocturnal predators.”

“Turbellaria has been almost entirely ignored by medical parasitologists and physicians.”

“The copious quantities of slime produced by terrestrial planarians in the process of locomotion would probably cause much discomfort in the respiratory passages.”

Brug, S. L. (1946). Pseudoparasitism of the Human Intestinal Tract. The Journal of Parasitology, 32(3), 222. doi:10.2307/3272672 

A report of finding presumed dead oocysts of the non-pathogenic organism Eimeria. No discussion section or other information about pseudoparasitism. No terminology definitions. A bust.

It serves you right….what dja’expect??

While researching ‘pseudoparasitism’ I stumbled (using ‘similar articles’ mode) the following article-  “Circumscribed scalp hair loss following multiple hair-cutter ant invasion.” Aghaei S1, Sodaifi M. Dermatol Online J. 2004 Oct 15;10(2):14.The first report of ant-induced hair loss was published by Radmanesh and Mousavipour, and the second by Shamsadini, both from Iran….Pheidole ants are believed to be lipophilic and therefore attracted to relatively greasy scalps. 

Apparent pseudoparasitism of the alimentary canal of a 5-year-old child by the millipede Brachyiulus lusitanus (Diplopoda: Julidae). Mowlavi G et al. Parasite. (2009) 

Brood parasitism in the sand martin, Riparia riparia: evidence for two parasitic strategies in a colonial passerine. Alves MAS1, Bryant DM. Anim Behav. 1998 Dec;56(6):1323-1331.The term quasiparasitism appears here. Only one hit and only one MeSH heading in advanced search

artifacts and pseudoparasites:

Very good and direct illustrations of pitfalls encountered in stool examination of animals

beautiful photomicrographs of artifacts seen in blood, stool and tissue.

Apparent pseudoparasitism of the alimentary canal of a 5-year-old child by the millipede Brachyiulus lusitanus (Diplopoda: Julidae), Gholamreza Mowlavi, Parasite, 2009, 16, 161-163  from the article: ” Pseudoparasites are free-living animals or parasites of other hosts acquired by an individual and which may survive for some length of time therein”

ON THE OCCURRENCE OF COLEOPTERA IN THE HUMAN INTESTINE.,Ronald A Senior-White, Indian J Med Res Vol.7,January 1920 pp 568-569 OPEN ACCESS “…were in the imaginal state…on being passed, clear themselves from the stool, and fly off.

Though seldom or never serious….is sufficiently common to have a vernacular name, Kurumini māndâmâ-(beetle disease) in Sinhalese….the author speculates that infection occurs when beetle ova or larvae are ingested with “the semi-decayed and extremely odoriferous forms of dried fish that form a regular article of diet with both the Sinhalese villager and the Tamil estate coolie…”

Helical Microorganisms in Blood Smears, Tudor Rares Olariu et al, Clinical Infectious Diseases 2011;53(5):497–498

The Loyola Worm

Lueck, J., Brewer, J. I., Aladjem, S., & Novotny, M. (1983). Observation of an organism found in patients with gestational trophoblastic disease and in patients with toxemia of pregnancy. American Journal of Obstetrics and Gynecology, 145(1), 15–26.

CHICAGO — Researchers have discovered a worm-like micro-organism they say is linked to toxemia, the second most frequent cause of death in pregnant woman and their fetuses for more than a century.’About 5 to 10 percent of all pregnant women will have the disease,’ Dr. Silvio Aladjem, chairman of Loyola University Medical Center’s obstetrics and gynecology department, said in an interview Wednesday.Aladjem and Dr. Judith Leuck performed experiments showing the syndrome is associated with a previously unknown microscopic organism similar to a parasite. They named it Hydatoxi lualba.

Hydatoxi lualba: The worm that wasn’t!, S. V. Phadnis et al, Journal of Obstetrics and Gynaecology, October 2013; 33: 669–670

Gau, G., Bhundia, J., Napier, K., & Ryder, T. A. (1983). THE WORM THAT WASN’T. The Lancet, 321(8334), 1160–1161.

‘Hydatoxi lualba’, an artefact, Polderman, AM et al,European Journal of Obstetrics & Gynecology and Reproductive Biology Volume 17, Issue 4, June 1984, Pages 301-304Abstract

“Blood samples from controls, pre-eclamptic patients and cord blood from their infants were examined for the so-called Hydatoxi lualba parasite. Using a further modified TBO staining technique on blood-smears made on slides cleaned manually, the ‘eggs, larva and worms’ could be demonstrated to be successive stages of artefacts originating from threads deposited by the cotton swabs used in manual cleaning. These successive stages of ‘worms’ could only rarely be found in smears made on industrially cleaned slides.”


pseudotumor (cerebri)


pseudomembranous (colitis)





whoever heard of…

pseudopatient– A false or spurious patient; spec. (in early use) a person feigning illness to obtain some benefit; (later) a person posing as a patient in order to investigate health care, provide training to medical staff, etc. (found in the Oxford English Dictionary [OED] )

who knew…

that there was a word pseudofaeces— [OED]:

With plural agreement. In a mollusc: a mixture of mucus from the gills and particulate matter from the water that collects in the mantle cavity and is expelled without passing through the digestive system.

don’t accuse me of ….pseudomania

 [Now rare] A mania for lying; an insane tendency to make false statements

1876   J. H. Trumbull True-blue Laws Connecticut & New Haven 31   The best excuse that can be made for him is, that he was a victim of pseudomania; that his abhorrence of truth was in fact a disease.

Fecal Microscopy Artifacts Mimicking Ova and Parasites ,Jane A. Colmer-Hamood, Laboratory Medicine February 2001, Number 2, Volume 32

importance of the ocular micrometer, reference drawings and photomicrographs…she says that B. hominis was prev. considered to be an artifact.

other terms mentioned by Colmer-Hamood:

***accidental parasite- found in fecal samples after humans ingest a non-infectious/non-infecting organism from another host– Accidental parasites include cheese-mite eggs and larvae or eggs of the plant nematode Heterodera radicicola from unwashed vegetables.

***Spurious infection–fluke eggs (commonly F. hepatica, C. hepaticum, D. dendriticum) are found in human feces. Occurs after infected animal liver is eaten and the ingested (non-infectious) helminth eggs are passed in the feces.

***artifacts– Rolled-up tomato or onion skin can appear to be roundworms; citrus fruit segments or bean sprouts can mimic adult pinworms and mucus casts often seen in persons whose food intake includes bulk-producing food fiber such as psyllium husk, can be mistaken for adult Ascaris species….pollen grains, plant cells, starch granules, algae, bean sprouts, fungal spores, plant hairs, 

A pseudo-outbreak of pseudo-parasite?—Pseudo-outbreak of intestinal amebiasis— California. MMWR. 1985;34(9):125-126.

“of 38 patients reported to have stool positive for E histolytica, on re-examination only 2 were shown to contain the dz. Probably due to the misidentification of leukocytes as being amoeba.”

The blog Creepy Dreadful Wonderful Parasites has some stunning photographs of mucus casts that might turn the head of the most discerning (and skeptical) parasitologist. The ‘ParasiteGal blog, a parsitology lab director from Minnesota:

Great section in the appendix III (Examination of feces) in Manson’s Tropical Diseases, good treatment of the pseudoparasite topic. 

Manson, Appendix III Manson’s Tropical Diseases, Philip H Manson-Bahr, 7th ed. 1923 London: Cassell & Co. “Of the larger intestinal parasites that can be seen with the naked eye, care must be taken not to mistake, as frequently happens, the pulp of orange for trematodes, banana fibers for small tapeworms, or pieces of cotton thread or celery for Oxyuris vermicularis, Ankylostoma duodenale, etc. plant pollen grains, fungal spores. Truffle spores can be mistaken for ova of Ascaris. Cheese mites can be found in the stool after ingesting them with contaminated cheese.”

A Terminal Curiosity

I say no more.

INTESTINAL SAND OR GRAVEL. JAMA. 1900;XXXV(22):1415-1416. December 1, 1900 doi:10.1001/jama.1900.02460480035010 

Sand colic in horses…Results: Twenty out of 30 control horses (66%) had one or more sand accumulations. In the present study; height, length and homogeneity of the accumulations were useful parameters for establishing a diagnosis of sand colic. Radiographically defined intestinal sand accumulation grades of up to 2 was a common finding in horses with no clinical signs from the gastrointestinal tract whereas most of the clinical cases had much larger grades, indicating larger sand accumulations. Conclusion: Further work to establish a reliable grading system for intestinal sand content is warranted, but a previously proposed grading system based on measurements of height and length may be an alternative for easy assessment of sand accumulations in the meantime. The present study indicates that a grade 1 – 2 sand accumulation in the intestine is a frequent finding in horses. Acta Veterinaria Scandinavica. 2008, Vol. 50, Special section p1-6.