What credible studies exist on Eurytrema pancreaticum infections in humans and their clinical outcomes?
Executive summary
Human infection with the pancreatic fluke Eurytrema pancreaticum is documented but extremely rare in the medical literature; most credible reports are isolated case reports or veterinary-focused reviews that treat human eurytremiasis as an incidental finding rather than a well-characterized clinical syndrome [1] [2] [3]. The available studies describe a spectrum from asymptomatic autopsy discoveries to symptomatic presentations mimicking biliary obstruction or pancreatic masses, but systematic, long-term clinical outcome data for humans are effectively absent [1] [4] [5].
1. Early autopsy and case-report evidence: the canonical 1983 Japanese report
The foundational human report often cited is the Ishii et al. case in which a 70-year-old Japanese woman with gastric cancer was found at autopsy to harbor roughly 15 adult Eurytrema pancreaticum worms in dilated pancreatic ducts, with morphologic description of adult flukes and eggs that established the diagnosis; blood eosinophils were reportedly within normal limits in that case [1] [6]. That report remains a touchstone because it provides direct parasitological description in a human pancreas, but it is a single postmortem observation and does not establish causation of symptoms or population-level risk [1] [6].
2. Contemporary clinical imaging and symptomatic presentations
More recent clinically oriented reports include a comprehensive imaging case of human pancreatic eurytremiasis describing a 43-year-old man who presented with obstructive jaundice and a pancreatic mass; authors emphasize that Eurytrema infection can present with biliary obstruction and mimic neoplasm on imaging, highlighting diagnostic challenges for clinicians [4]. The CDC’s DPDx case series also documents an ERCP identification of a live parasite in the biliary tree of an elderly patient with abdominal complaints, underscoring that although the pancreas is the usual site, parasites can be detected in bile ducts and present with obstructive symptoms [5]. These clinical reports illustrate that symptomatic human infections can occur, but they remain single cases rather than systematic case series [4] [5].
3. Reviews and veterinary literature: low pathogenicity but potential underdiagnosis
Review articles and veterinary-focused studies characterize E. pancreaticum as primarily a ruminant parasite with "low pathogenic" classification in most hosts, and they consistently note human infections as accidental and often incidental at necropsy or in stool exams [7] [2] [3]. Authors of reviews raise the possibility of underdiagnosis in humans because routine coproparasitological testing can yield false negatives, and surveillance in human populations is limited compared with veterinary screening, implying selection and detection biases in the literature [2] [3].
4. Laboratory and translational research: parasite biology and drug susceptibility
Laboratory studies have characterized the biology of E. pancreaticum—molecular work such as miRNA profiling provides genomic resources relevant for understanding parasite biology and potential control measures—while in vitro drug assays have tested praziquantel and triclabendazole against adult flukes, yielding preliminary susceptibility data but no established human treatment trials [8] [9]. These studies are valuable for translational research but do not substitute for clinical evidence about therapeutic outcomes in infected humans [8] [9].
5. Pathophysiology hypotheses and gaps in human outcome data
Experimental and animal-pathology studies document pancreatic duct infection leading to chronic interstitial pancreatitis and reduced productivity in livestock, and some authors propose Eurytrema infection as a model to study pancreatic pathology or links to metabolic disorders; however, extrapolation to human clinical outcomes is speculative because longitudinal human pathology or cohort studies are lacking [10] [2]. The existing human literature does not provide robust data on long-term outcomes, response to antihelminthic therapy in people, or population-level prevalence outside scattered case reports [10] [2].
Conclusion: what the credible studies do — and do not — show
Credible human evidence consists chiefly of isolated case reports and a small number of imaging/diagnostic case studies (Ishii et al.; imaging report; CDC DPDx), supplemented by veterinary reviews and molecular studies that place E. pancreaticum as a ruminant parasite that can occasionally infect humans; these sources collectively indicate possible symptomatic presentations (obstructive jaundice, pancreatic mass mimic) but do not offer systematic outcome data, incidence estimates, or evidence-based human treatment protocols [1] [6] [4] [5] [7] [2] [8] [9]. The literature’s hidden tension is disciplinary: rich veterinary and basic-science attention contrasts with sparse clinical epidemiology in humans, producing credible descriptions but limited clinical guidance [7] [2].