What case reports or documented human infections with Eurytrema spp. exist and how were they diagnosed?
Executive summary
Human infections with Eurytrema spp. are documented but exceedingly rare: classical reports include an autopsy finding of Eurytrema pancreaticum in a Japanese woman and several clinicopathologic case reports including an ERCP-detected infection and a 43-year-old man with obstructive jaundice; diagnosis in these reports rested on direct recovery or morphological identification of adult flukes and eggs plus histopathology and imaging rather than routine stool screening [1] [2] [3] [4]. Epidemiologists and parasitologists warn that most human eurytremiasis reports are sporadic, that routine parasitologic tests have low sensitivity, and that some claims of human emergence reflect misinterpretation of life cycle and ecology rather than robust case-series data [5] Brazil" target="blank" rel="noopener noreferrer">[6] [7].
1. Documented individual human cases: autopsy and historical reports
A seminal human record describes about 15 adult Eurytrema pancreaticum flukes found in dilated pancreatic ducts at autopsy of a 70‑year‑old Japanese woman; worms and eggs were morphologically characterized by measurements of suckers and egg dimensions supporting species identification, and authors noted this represented the second documented human eurytremiasis at the time [1] [2]. Additional historical clinical reports cited in reviews include an infection detected by endoscopic retrograde pancreatography (ERCP) reported in the Japanese literature and summarized in reviews [3].
2. Recent clinical case with imaging, histology and surgical correlation
A contemporary case report provides the most detailed modern clinical record: a 43‑year‑old man presented with obstructive jaundice and a pancreatic mass; imaging and operative specimens showed multifocal granulomatous lesions containing numerous parasite eggs, and the final diagnosis was pancreatic eurytremiasis based on histology and identification of eggs consistent with Eurytrema spp. [4]. That report explicitly frames itself as the first comprehensive imaging-pathology description of human pancreatic eurytremiasis, linking clinical jaundice and a pancreatic tumor‑like lesion to the parasite [4].
3. Diagnostic methods documented in case reports and reviews
Confirmed human diagnoses in the literature have relied on direct demonstration of parasites or eggs: macroscopic recovery of adult flukes at autopsy, microscopic morphometrics of eggs and suckers, ERCP visualization of ductal parasites, and histopathology showing granulomas and embedded eggs [1] [2] [3] [4]. Multiple sources caution that coproparasitological methods (fecal egg detection) and conventional concentration techniques can be insensitive for Eurytrema in both animals and humans, and negative fecal tests do not exclude infection—hence imaging, endoscopy, histology or retrieval of worms are decisive when available [8] [6].
4. Epidemiology, life cycle and why human cases are rare but occasionally reported
Eurytrema spp. are primarily parasites of ruminants and other animals, with high prevalences reported in cattle in some regions (including parts of Brazil) and a life cycle involving a land snail (Bradybaena similaris) as first intermediate host and grasshoppers/crickets as second intermediate hosts; human infection is believed to occur only by ingesting infected insects and is therefore accidental and uncommon [9] [5] [10]. Brazilian researchers have debated whether human infection is underestimated due to low test sensitivity versus whether suggestions of large human burdens reflect misinterpretation of the parasite’s terrestrial life cycle and transmission routes [5] [6].
5. Clinical significance, diagnostic challenges and gaps in the record
Reports indicate Eurytrema infection in humans can be subclinical or cause chronic fibrosing pancreatitis and pancreatic insufficiency; some animal studies and limited human data note altered pancreatic enzymes in heavy infections, but human clinical spectra remain poorly defined because confirmed cases are so few and diagnostic tests lack sensitivity [8] [7] [10]. The literature highlights clear gaps: few molecular confirmations, a small number of verified human case reports, limited prospective screening in endemic settings, and a risk that ecological misunderstandings can exaggerate perceived human burden—sources used here stop short of broad prevalence estimates and emphasize rarity [5] [6].