Adil writes:

Dear Doctors,

Firstly thank you for your TWIP smart banter and utterly engaging podcast. After multiple weeks of being right and yet reticent to take my shot I will hazard a guess. Initially I thought scabies because the itching was noted to be worse at night. The punctuation and explicit reference to unused bedding made me think of body lice however. The regions impacted seemed to align with this as well. Unlike with last episodes diagnosis of Babesia I am not at all confident but there it is. Hope all is well with you and that I can send forth future response with a bit conviction in my diagnosis.


Caitlin writes:

Dear TWiP Triptych,

First of all, I want to thank you for your awesome podcasts! I have been on a TWiX bender since April 2017, averaging about 1.3 podcasts per day, and just today I cracked 100 left to go on TWiV. Being fully caught up is in sight! Your podcasts have helped me get through finding my first job after graduating, many hours in the lab, a commute from hell, the stress of wedding planning, and a whole host of difficult personal situations. You gentlemen (and on the other podcasts, ladies) are truly amazing.

I have attached a photo of a TWip Triptych for your entertainment.

TWiPtriptychRegarding the TWip 158 case study:

This unfortunate patient has so many symptoms that I doubt a single parasitic infection could explain all of them. To complicate matters further, it is likely that some, but not all, of them are indeed trauma or drug related.

The following symptoms seem likely to be unrelated to parasites:

The brief spell of blindness – Onchocerca volvulus can cause blindness, but that is not temporary and he was nowhere where he could have picked that up. This was more likely to be psychosomatic or drug-induced.

The fork-headed worms in the toilet – I couldn’t find any parasites that fit this description well, and he didn’t successfully get a picture. Furthermore, it would be odd for someone with an intestinal parasitic infection to excrete worms once and only once. I find it more likely that this was a hallucination. (Which substances does he usually abuse? That could be relevant. Also, I may be reading too much into it, but the fact that he dropped the phone in the toilet when trying to take a picture may indicate that he was not sober at the time.) Alternatively, it was something already present in the toilet (I recall a story about a patient who mistook mayfly larvae in the toilet for some kind of excreted worm.)

The other symptoms – namely, the calcifications in the bladder, the crusted and ulcerated skin, and the white objects, are more compelling.

The calcifications in the bladder are probably caused by Schistosoma haematobium, which the man would have acquired during his trip to Egypt some time ago. The calcifications would not appear until a while after infection, and therefore the timing makes sense. The only issue here is that there was no mention of blood in the urine, but I don’t think that appears in every patient, or at every stage of infection. This infection might be missed in the stool O&P, but could be picked up in an antibody test. The treatment should be praziquantel. (, Parasitic Diseases 6th Ed.)

The skin ulceration could be caused by scabies, which is common in Haiti. However, if this were the case it would have been diagnosed easily when the skin scrapings were examined, but only inflammation was observed at that point. It could potentially be psychosomatic, but on the other hand, the white moving objects that came out of his skin were definitely real, since he took videos of them. (Unless he had somehow faked them; it would not be the first time some poor soul suffering from Ekbom’s syndrome did such a thing in a desperate attempt to be taken seriously. However, it’s quite likely that they were real.) This would suggest a case of myiasis, i.e. infection of the skin with some kind of maggot. Potential suspects here are Cochliomyia, the New World screwworm; Wohlfahrtia vigil or opaca (it seems those only infect children, but perhaps they were able to get into his highly irritated skin); Cuterebra (less likely, as those larvae are black); or one of the species of Sarcophaga, which are known for infesting wounds and might have been attracted to the skin ulcerations. This does not explain how the skin irritation began, but it might have started as a case of delusional parasitosis that caused the patient to scratch his own skin excessively. Ironically, this could have subsequently caused a real infestation.

I understand that the best way to get rid of a maggot infestation is to remove the maggots physically. This can be done by using forceps, after inducing the larvae to come to the surface using petroleum jelly or oil. Topical or oral ivermectin may also be used to kill or drive out the larvae (

This poor patient was suffering from a great deal more than any parasitic infections he may have had. I hope he got the medical and psychological help he needed.

If I am lucky enough to win the book, I would rather that Parasitic Diseases goes to someone who needs it more. I have no professional use for it while others do, and am quite happy with the free PDF (again, you guys are the best!). I wouldn’t mind the poetry book, though, unless it’s available as a PDF.

Caitlin, from Waterloo, Ontario Canada

Hannah writes:

Dear TWiP hosts,

I think the patient has Ekbom syndrome, also known as delusional parasitosis, with a concurrent parasitic infection. Red flags for Ekbom syndrome include his history of visiting doctors with skin scrapings and his biologically implausible description of arthropods with compound eyes living in his skin (note: mites, which do live in skin, do not have compound eyes) or bursting forth from ulcers in his skin (not unheard of, but the insects that do this also do not match his description). His history of drug use may be a contributing factor here and/or may be a coping mechanism to deal with underlying mental issues that cause him to see/feel things that aren’t physically there. All the things that he’s putting on his skin may be causing irritation as well.

That being said, the high eosinophil count suggests that he does have SOMETHING, even if it isn’t what he thinks he has. Given his bladder issues and history of swimming in fresh water in Egypt, there is a very good chance he has Schistosoma haematobium. These parasites are widespread in Egypt, are acquired by swimming in fresh water, and can cause an elevated eosinophil count, calcification of the bladder periphery, and hematuria. Eggs are found primarily in the urine, so a negative stool ONP does not rule out this diagnosis, and although you mentioned that his Schistosoma serology tests came back negative, sensitivities of different tests vary widely ( His description of “forked worms” could describe a mating S. haematobium pair, but it is unlikely that they would be passed out in the urine or that he would notice them if they were (they’re ca. 2 cm long and very thin), so I suspect this may be another delusion.

Speaking of trematodes, I recently came across this paper while looking for something completely different: “Social organization in a flatworm: trematode parasites form soldier and reproductive castes”

You covered a paper about social trematodes from some of the same authors back in 2016 (, but this 2010 paper, in which they first described the phenomenon, is absolutely worth a read. It’s also open access, unlike the paper covered in TWiP 106.



Brian writes:

Hello Twipsters,

This was a tough case but I think our fireman from New York may have schistisomiasis due to  S. haematobium which was likely acquired during his time in Egypt. I think he may also have had a brief infection due to myiasis acquired in Haiti likely a botfly.


Kevin writes:

TWiP 158  Case Submission

71ºF /22ºC-overcast.

This 50ish year old man with a conviction that his body is infected with parasites. This case has a very low signal to noise ratio–that is lots of noise, not much signal. I have divided up this patient’s findings into three categories: subjective, objective and unclassified. This will, I hope, filter out much of the background noise that threatens to derail the diagnostic process and reinforce cognitive biases.


–white skin lesions that ‘hatch’ and liberate swimming creatures:

This dramatic patient report is not consistent with any known arthropod infestation. There are no known insect,crustaceans, or other invertebrate that burrows and develops in the dermis and liberates an aquatic or free-swimming form. Patient testimony will be held to be at best a mis-perception and at worst a delusion.

–“forked head worms” seen in toilet after defecating. Unspecified which orifice produced the worms.

Patients may mis-perceive detritus in the toilet bowl to be some kind of living creature. Patients are known to bring to clinic all manner of vessels containing floating amorphous fragments ( it is axiomatic that such jars are poorly sealed and possess ill-fitting lids.) The description of ‘fork head’ does not match any known intestinal helminth. His exposure to fresh water in Egypt raises the possibility of Schistosoma infection, but rectal or urethral passage of adult worms is not expected.

–self-collected specimens/sample

Historically this has been called “the match-box sign,” a description of patients who brought a match-box to clinic containing suspected parasites. Perhaps a bit unfairly, this ‘sign’ has been used in part as evidence of delusions of parasitosis. The match-box has given way to zip-lock bags and other containers. Our patient’s samples can be interpreted as his genuine concern to be listened to and relieved of suffering.

–self-produced videos of organisms

I classify this as modern version of ‘the match-box sign.’ (see above)

–temporary blindness / transient visual loss

The old term for this was ‘hysterical blindness’, a term which has no doubt been cashiered. A more neutral description would be a conversion reaction, a manifestation of severe somatoform disorder. Examples of physiologic transient blindness are amaurosis fugax (due to embolus/ischemia, tho almost always monocular), migraine, giant cell arteritis, optic neuritis (e.g. multiple sclerosis). Infectious causes of visual loss such as CMV retinitis, luetic retinitis, etc are not relevant to our case. A thorough retinal exam and syphillis serology should be done. It is highly likely, considering the entirety of the clinical case, that his “blindness is psychological in origin.


–travel exposures, Haiti 2009, Egypt 2009?

Patient could have been infected with a wide variety of helminth or arthropod infections, infestations or bites. However, there is little in his overall history that suggests a specific organism.

–hematuria (presumably NOT self-reported)

Patient’s fresh water exposure in Egypt raises the possibility of Schistosoma hematobium infection. He presumably had limited exposure and if infected would likely have a low worm burden. (more below)

–radiographic evidence of bladder wall calcification

Again raises the S. hematobium question, which can be associated with this finding. Other conditions that can cause bladder wall calcification: tuberculosis, various urothelial cancers, amyloidosis, post-radiation fibrosis, cytotoxin exposure. Another look at a concentrated urine specimen for ova and perhaps a nucleic acid amplification test or rectal snip exam as outlined in PD6 may rule out the rather low likelihood of schistosomiasis. At the risk of entering into a folie a deux, empiric treatment with praziquantel could be considered.

–facial, extremity, scrotal excoriations

The dermatological literature formerly used the term ‘neurotic excoriations’. I personally do not like to use terms that patients might misinterpret as demeaning or insulting. In view of our patient’s substance abuse history the diagnosis of drug-induced formications should be considered. These self-induced lesions are colloquially called “coke bugs,” “meth mites,” and “amphetamites”. Patient may also have a hypersensitivity reaction to the multiple nostrums that he is applying to his skin.

–multiple negative laboratory studies

Where there’s no smoke there is probably no fire. Possible that patient is having a post-infestation ongoing pruritis, a kind of prurigo nodularis, a vicious cycle of scratch-itch-ad infinitum.

-absolute eosinophil count of 700 cells per microliter

Eosinophil counts below 1500 cells/microliter are considered to be mild. Note reference below that states, “Despite extensive evaluation, up to 60% of travelers with eosinophilia never have an underlying cause for their eosinophilia identified.” Unfortunately, our patient’s low level eosinophilia contributes little to a strong case for infection or infestation. Finally, to leave no stone unturned, mention should be made of uncommon cases of cutaneous T.solium dermal cysts, cutaneous sparganosis, and cutaneous manifestations of echinococcosis.


–Self-report/testimony that previous skin biopsy showed arthropods with ‘compound eyes.’

Note that only insects, crustacea, and horseshoe crabs have compound eyes. Holometabolous insect larva do not have compound eyes, which eliminates myiasis as a consideration. Arachnids (e.g. mites) have simple eyes and often are eyeless. If there is any factual basis for these highly suspect skin biopsy results there is a possibility of pseudoparasite detection (where incidental or household insects such as psocids are misidentified as infectious agents–see excellent Mathison ref).


I believe that this patient may have contracted a cutaneous infestation such as scabies in 2009 which subsequently cleared, but resulted in a chronic self-induced pruritic dermatitis: lichen simplex chronicus or prurigo nodularis. Travel to Egypt may have resulted in a chronic S. hematobium infection. However, the patient’s primary problem is an obsessive preoccupation with infection and infestation including compulsive documentation, self mutilation and dogged physician seeking… to wit: delusional parasitosis, which may be exacerbated by his substance use disorder. He does not seem to have features of the currently fashionable affliction of Morgellon’s ‘disease’. Psychiatry referral, anti-psychotic medication or cognitive behavior therapy and treatment for substance use disorder may mitigate his unfortunate state of suffering.

Thanks for bringing me to this tango of delusions.


Ammonium bituminosulfonate or ammonium bituminosulphonate (synonyms of ichthammol, brand name: Ichthyol–sulfonated oil shale. Called “drawing salve” or “black ointment” promoted in 1886 by famous German dermatopathologist Paul Unna.

Mites do not have compound eyes. Arthropods with compound eyes include the insects, many crustacea, and the horshoe crab. Most holometabolous insect larvae DO NOT have compound eyes…

This should discounT myiasis as a consideration….holometabolous insect larvae have single chamber eyes called stemmata. Mecoptera are unique in holometabolous insects in that their larvae have compound eyes. In the present study the cellular organisation and morphology of the compound eyes of adult individuals of the scorpionfly Panorpa dubi…

Eosinophilia, Prim Care. 2016 Dec; 43(4): 607–617. Anna Kovalszki, MDa,and Peter F. Weller, MDb

“elevated” generally interpreted to mean absolute eosinophil counts (AEC) of greater than 450-550 cells/μL

Our patient’s degree of eosinophilia can be characterized as ‘mild’. AEC of <1500 cells/μL can be seen in allergic disorders, asthma, atopic dermatitis, drug allergy, eosinophilic esophagitis. AECs of > 1500 cells/μL

Eosinophilia in Infectious Diseases Immunol Allergy Clin North Am. 2015 Aug; 35(3): 493–522. Elise M. O’Connell, MD and Thomas B. Nutman, MD

…for perspective, acute schistomiasis counts: “Eosinophilia is present in nearly all patients commonly ranging between 3,000-7,000/μl”

Accuse me of participating in a folie à deux, but I searched PD6 for the words “forked head” and went a-begging.

Eosinophilia in Returning Travelers and Migrants, Dtsch Arztebl Int. 2008 Nov; 105(46): 801–807. Stephan Ehrhardt, Dr. med.1 and Gerd D. Burchard, Prof. Dr. med.

Eosinophilia in the Traveler Conclusions….

Despite extensive evaluation, up to 60% of travelers with eosinophilia never have an underlying cause defined for their eosinophilia identified. In the cases where patients remain asymptomatic and testing is negative, it is reasonable to simply monitor the eosinophil count periodically, as most eosinophilia in these cases will self-resolve. Another approach is to treat empirically for soil transmitted helminths and flukes with a one-day treatment of albendazole, ivermectin, and praziquantel, and monitor for eosinophil resolution.

Chronic schistosomiasis caused by S. haematobium is a common infection in Africa and should be suspected in a patient from there with symptoms of hematuria, chronic suprapubic pain, or obstructive uropathy [11, 151]. Hematuria and dysuria can develop within months of infection (due to bladder ulcerations}, occur intermittently, and hydronephrosis may develop within the first 3 years of infection [11, 152]. In women, eggs can also deposit around the cervix, vagina, and ovaries [151], and has been associated with infertility and increased susceptibility to HIV [153, 154]. While s may be elevated early in chronic infection, it typically decreases over subsequent year

RE Sparganosis…Spirometra mansonoides is the main species in North and South America…

Disseminated cutaneous cysticercosis and neurocysticercosis: A rare occurrence Indian Dermatol Online J. 2012 May-Aug; 3(2): 135–137. S. Sacchidanand, P. Namitha, M. Mallikarjuna, and H. V. Nataraj

A 19-year-old female patient presented with multiple swellings of 1 year duration all over the body…lesions were asymptomatic…Absolute count was 890/cu mm.

Cytological diagnosis of parasites presenting as superficial nodular swelling: report of 35 cases

J Parasit Dis. 2012 Apr; 36(1): 106–111. Yogesh Kumar Yadav,1 Oneal Gupta,1 and Roopak Aggarwal2

hydatid cyst may also occur in subcutaneous tissue

Cutaneous Disease as the First Manifestation of Cystic Echinococcosis Am J Trop Med Hyg. 2016 Aug 3; 95(2): 257–259. Virginia Velasco-Tirado,1 Manuela Yuste-Chaves,1 and Moncef Belhassen-García2,

We propose that this continuous antigenic trigger and repeated scratching could potentially result in clinical manifestations in our patient, which were resolved using antiparasitic treatment.

Escaping compound eye ancestry: the evolution of single-chamber eyes in holometabolous larvae

Elke K. Buschbeck Journal of Experimental Biology 2014 217: 2818-2824; doi: 10.1242/jeb.085365 OPEN ACCESS

Abnormal calcifications in the urinary tract. Radiographics. 1998 Nov-Dec;18(6):1405-24. Dyer RB1, Chen MY, Zagoria RJ.

Schistosomiasis of the bladder may produce mural calcification with a typical thin arcuate pattern and may be associated with calcification in other portions of the urinary tract. Bladder wall calcification can be seen in transitional cell carcinoma of the bladder…urachal carcinomas may also cause typical calcification of the dome of the bladder…other considerations: alkaline incrusted cystitis, cytotoxin cystitis, tuberculosis and post-radiation exposure fibrosis and calcification. Primary amyloidosis may also cause submucosal calcification of the bladder.

PD6: While most schistosome eggs appear in feces, urine should be examined for the presence of eggs of S. haematobium if this species is suspected. The urine sample should generally be collected close to noon, when egg excretion is usually maximal. Urine may have to be concentrated by sedimentation to reveal the few eggs present. S. haematobium eggs may also be seen in stool and rectal snip specimens, but their numbers are typically small in these samples. A number of nucleic acid amplification tests (NAATS) tx praziquantel…40 mg/kg per day orally in two divided doses for one day.

50ml red clover salve—$20.00 amazon….

Patient Care, Nov 7, 2006 Vol 2, Drug-Induced Formication It was first reported in chronic cocaine users in 1889.1 Drug-induced formication has been referred to as “coke bugs,” “meth mites,” and “amphetamites,” depending on which drug caused the hallucination. Patients with this disorder often have self-induced dermatosis caused by intense picking and scratching of the skin. The lesions may appear as multiple well-circumscribed, erythematous papules and partially healed scabs in easy-to-reach areas, such as the face, scalp, neck, anterior thighs, and arms (lesions on the dorsal forearms are often worse on the side opposite the patient’s dominant hand).1. de Leon J, Antelo RE, Simpson G. Delusion of parasitosis or chronic tactile hallucinosis: hypothesis about their brain physiopathology. Compr Psychiatry. 1992;33:25-33. Wilson FC, Uslan DZ. Delusional parasitosis. May Clin Proc. 2004;79:1470. Anonymous. The matchbox sign. Lancet. 1983;2:261.

Magnan’s sign, formication, or parasitosis

Magnan and Saury, 1889 Trois cas de cocainisme chronique; Comptes rendus SociMé de Biologie; p. 60; Paris, 1889

(Magnan and Saury, 1889; Maier, 1926; Lewin, 1931)

different from delusions of parasitosis….”matchbox sign”

Delusional parasitosis: Worms of the mind Ind Psychiatry J. 2012 Jan-Jun; 21(1): 72–74. Jyoti Prakash, R. Shashikumar, P. S. Bhat, K. Srivastava,1 S. Nath,2 and A. Rajendran

The Pre-senile Delusion of Infestation History of Psychiatry, 14/2, 229–256 K. A. EKBOM Translation of: Ekbom, K. A. (1938) Der praesenile Dermatozoenwahn. Acta Psychiatrica et Neurologica Scandinavica, 13, 227–59. The translators thank Karl Ekbom (junior) for granting us permission to publish this translation of his father’s paper.

Chris writes:

Good morning professors,

its is a conformable 76F here is Stonybrook New York. So a little follow up from last episodes questions about ticks in Long Island, this weekend I went hiking at Habbard county park (near the south fork) and I smashed my tick record! I found several thousand ticks on me.  At first what I thought was some unusual sticky brownish sand on my shoes I quickly realized were actually thousands of ticks. I noticed this after a fairly intense itching feeling about an hour into my hike. the weird thing is although I had several thousand ticks on me, the three other people I was hiking with had several less ticks on them by orders of magnitude. Due to the fact this isn’t the first time I have had a disproportionate amount of ticks on me while people near me had none, I came to the conclusion that my shoes were very good for grabbing on and threw them out immediately. So if anyone on long island here is listening learn from me and NEVER forget the deet! Lucky the thousands of bites on me (which look like chicken pox) were all from nymph lone star ticks which don’t carry lyme’s and because it is their first stage they haven’t picked up any diseases, excluding the red meat disease that everyone seems to bring up when I tell them this story but i’m not too worried about that.  Additionally, one last lesson learned from this ordeal is that Front line doesn’t work for pets on long Island, the insects have become resistant. This was also learned the hard way as my poor pup was dropping ticks for a few days, he is doing better now though.

Now onto the case, I think that the patient is suffering from schistosomiasis. I think the reported white specs popping off and swimming may just be dead skin falling off due to drug use. Additionally because he reports being infected with a “fork headed worm” he might be prone to delusional thought as I can find anything on a fork headed parasitic worm. some of the reasons I believe he is suffering  schistosomiasis is because this parasite can cause  elevated eosinophil, calcification of the bladder from the eggs, and is very present in Egyptian freshwater where it is transmitted in its free living cercaria stage.  The negative ONP is a little surprising if it is  schistosomiasis, this could be a false negative and may take more than one test or if it is a new infection if could not be producing eggs although this is unlikely because calcification of the bladder would take time. This was a tough one I hope i got it right.

Now I have a few questions for Vincent about viruses. So I know Vincent would very much enjoy sequencing ocean water as he has mentioned numerous times on TWIV, but what part of the ocean?  Specifically I am curious about how the viral loads of the ocean would vary from the surface or the bottom. For example there is a lot of pressure at the bottom of the ocean, would viruses be able to survive this? Are viruses dense enough to even sink to the bottom? if they are dense enough to sink would the sea floor be a rich mat of viruses? could there be ancient viruses on the sea floor as it would take a long time for such a small particle to fall 1000s of meters? The ocean is stratified in density (as well as many other properties) would different sized viruses also be stratified along with the ocean’s layers, like one giant agarose gel? I know these questions are a little off topic for this podcast but viruses infect parasites and are themselves parasitic so not that off base, plus these questions could be asked for parasite eggs in the ocean as well. I would ask this for TWIV but I’m only at episode 126 and I’m still working on catching up (i like to do it in order so i can understand the context of the episodes better)

Lastly, I loved the most recent episode of TWIP, and absolutely love when ever you guys talk about ecological parasitism as it is a fascinating field! I would love to hear you all talk about the Dilution hypothesis and possibly bring  Dr. Richard S. Ostfeld form the carry institute on to talk if you discuss ticks in the future as his work is really cool.

Sorry for such a long email but I hope becoming a patreon helps make up for it.

Warm regards,


Carl writes:

Dear TWIP,

Everything in this case, except the eosinophilia, is consistent with delusional parasitosis (or delusional infestation as some people call it).  The consulting of many doctors, the injuries produced by repeated scratching, the bringing in of samples that are actually innocuous, and the reporting of biological impossibilities that are horrifying but somehow escape being captured as hard evidence– all these are familiar to anyone who has read a New Yorker article about delusional parasitosis, as I have.  I confirmed this diagnosis by consulting an article on delusional parasitosis in Clinical Microbiology Reviews, which is more prestigious that the New Yorker. (  It’s a sad case, because it’s an intractable and disabling syndrome, but a parasitologist can’t do anything about it. You might want to get a brain MRI, since in one study, about half of people with delusional parasitosis had detectable organic brain problems, and in some cases those were treatable.  Failing that, you should refer him to psychiatry.

What about the mild eosinophilia?  I suggest that the eosinophilia is in fact unrelated to any parasite.  Apparently eosinophilia in the mild range, discovered in a patient with no parasites or other signs of illness, is often of obscure origin.  An authoritative-looking web site ( states

The optimal evaluation of the asymptomatic traveler or immigrant with eosinophilia is uncertain. Up to 50 percent of such patients never have a cause of their eosinophilia identified despite exhaustive evaluation.

You should work up the patient for non-parasitic causes of eosinophilia, but not be shocked if you don’t find anything.  So I’m prepared to ignore the eosinophilia. I never thought this would use that sentence in a letter to TWIP!