Clinical, Diagnostical, and Epidemiological Findings at First Diagnosis of Alveolar Echinococcosis: A Single-Center Cohort Study.

Introduction: Alveolar echinococcosis (AE) is a parasitic disease caused by the larval stage of Methods: The data of patients who first presented with AE to the outpatient clinic for infectious diseases at Ulm University Hospital between 1 January 2019 and 31 December 2023 were analyzed and compared to previous cohorts. Diagnostic imaging (whole-body fluoro-deoxyglucose positron emission tomography combined with CT or MRI if feasible or at least abdominal ultrasound) and laboratory tests (echinococcal serology, immunoglobulin E [IgE], liver parameters) were performed upon first admission. Liver lesion characteristics were assessed solely using imaging obtained at our clinic. Data on symptom presence, occurrence of incidental diagnoses, initial pharmacological treatment and assessment of potential curative operability were evaluated. Results: During the study period, 219 patients with AE (slight female majority, average age 56.7 years) made their first presentation, mainly from southeast Baden-Württemberg ( Conclusion: Compared to previous cohorts of the clinic, annual AE case numbers have steadily increased, with persistent geographic clustering. This indicates that the importance of AE will continue to increase. The study provides an overview of the circumstances surrounding the initial diagnosis of AE and shows in which patients in outpatient care it should be considered a differential diagnosis. WHO stage distribution remained consistent, but asymptomatic and incidental cases increased notably, underscoring the expanding use of routine abdominal ultrasound in primary care and the importance of awareness of AE. Larger lesions were associated with symptom presence as well as elevated IgE and positive echinococcal serology - both indicators of increased disease activity and poorer prognosis. Therefore, lesion diameter, total IgE, and serology should be incorporated into disease staging and decisions regarding surgical resection. Especially in symptomatic patients and in higher WHO stages, AE primarily leads to elevated cholestasis parameters, which reflect a biliary outflow obstruction and correlate with a poorer outcome. In ambulatory patients with unexplained cholestasis, such findings should be a reason to consider an AE.