Abstract
INTRODUCTION: Alveolar echinococcosis (AE) is a parasitic disease caused by the larval stage of Echinococcus multilocularis with increasing incidence in traditional prevalence areas of Central Europe and expanding to Eastern and Northern Europe. Primarily affecting the liver, AE can cause severe complications through invasive growth. Diagnosis involves clinical assessment, imaging, and serology. Lesions are surgically removed if possible; otherwise, long-term benzimidazole treatment is indicated. The study aimed to comprehensively analyze clinical, imaging, serological, and laboratory findings at initial diagnosis. 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 (n = 68) and southwest Bavaria (n = 90). Most presented in advanced WHO stage IV (38.2%), with 43% showing lesions extending into organs neighboring the liver. Case definition and WHO stage showed a significant relationship (χ(2)[8, N = 217] = 30.2, p < 0.01, V = 0.26). A negative correlation was observed between lesion number and size, whereby larger lesions (above the average lesion size of 66.6 mm) were indicative of higher WHO stages (stages III and IV) (r (s) -0.22, p = 0.02). Higher WHO stages and larger lesions were associated with elevated IgE levels and positive echinococcal serology. Furthermore, they correlated with higher values of ALT (r (p) = 0.2, p < 0.02), AP (r (p) = 0.18, p < 0.04) and γGT (r (p) = 0.27, p < 0.01). The most frequent and highest elevation was seen in γGT. Over half (n = 118, 53.9%) were asymptomatic at diagnosis; an increasing lesion size was more frequently associated with symptoms. The diagnosis was an incidental finding in 55.5%. Albendazole was the initial drug therapy for all patients. Surgery with curative intent was considered feasible in 42.7%, predominantly at lower WHO stages and single-lobe involvement. 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.