All patients with Alveolar Echinococcosis (AE) seen at the specialized treatment unit in Ulm between January 1992 and December 2011 were included in the database. Follow up ended on 31.12.2012. Cases were defined to the likelihood of diagnosis as a "possible", "probable" or "confirmed" case . Diagnosis of AE was based on clinical presentation, epidemiological history, pathognomonic imaging findings, specific laboratory results, such as immunodiagnosis or histopathological findings in resected/ biopsied specimens, and/or detection of nucleic acid sequences in such specimens. The location of the larval lesions and its spread at diagnosis was documented using the PNM classification. Treatment with benzimidazoles was followed the WHO-IWGE recommendations. Treatment efficacy was monitored by US examination and FDG-PET scan or MRI. To categorize each case at each visit the terms "cured", "stable" or "progressive" were used. Patients' data was assessed at each visit; missing information was obtained from hospital records or the family doctor. Names were anonymized and data was stored in a Microsoft Excel database. Statistics were done with SAS version 9.3.