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Patients with immunosuppression are at increased risk for occurrence, delayed diagnosis, and progression of AE.

Hepatic Alveolar Echinococcosis (HAE), caused by larvae of Echinococcus multilocularis, is a rare but potentially lethal parasitic disease. The first diagnostic suspicion is usually based on hepatic ultrasound exam performed because of abdominal symptoms or in the context of a general checkup; HAE diagnosis may thus also be an incidental finding on imaging. The next step should be Computed Tomography (CT) or Magnetic Resonance Imaging (MRI). They play an important role in the initial assessment of the disease; with chest and brain imaging, they are necessary to assess the PNM stage (parasite lesion, neighboring organ invasion, metastases) of a patient with AE. Performed at least yearly, they also represent key exams for long-term follow-up after therapeutic interventions. Familiarity of radiologists with HAE imaging findings, especially in the endemic regions, will enable earlier diagnosis and more effective treatment. Fluorodeoxyglucose Positron Emission Tomography (FDG-PET) is currently considered to be the only noninvasive, albeit indirect, tool for the detection of metabolic activity in AE. Delayed acquisition of images (3 hrs after FDG injection) enhances its sensitivity for the assessment of lesion metabolism and its reliability for the continuation/withdrawal of anti-parasite treatment. However, sophisticated equipment and high cost widely limit PET/CT use for routine evaluation. Preliminary studies show that new techniques, such as contrast-enhanced ultrasound (US), Dual Energy CT or Spectral CT, and Diffusion-Weighted MRI, might also be useful in detecting the blood supply and metabolism of lesions. However, they cannot be recommended before further evaluation of their reliability in a larger number of patients with a variety of locations and stages of AE lesions.

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Pathogenesis of chronically developing alveolar echinococcosis (AE) is characterized by a continuous, granulomatous, periparasitic infiltration of immune cells surrounding the metacestode of Echinococcus multilocularis (E.multilocularis) in the affected liver. A detailed cytokine and chemokine profile analysis of the periparasitic infiltrate in the liver has, however, not yet been carried out in a comprehensive way all along the whole course of infection in E. multilocularis intermediate hosts. We thus assessed the hepatic gene expression profiles of 18 selected cytokine and chemokine genes using qRT-PCR in the periparasitic immune reaction and the subsequent adjacent, not directly affected, liver tissue of mice from day 2 to day 360 post intra-hepatic injection of metacestode. DNA microarray analysis was also used to get a more complete picture of the transcriptional changes occurring in the liver surrounding the parasitic lesions. Profiles of mRNA expression levels in the hepatic parasitic lesions showed that a mixed Th1/Th2 immune response, characterized by the concomitant presence of IL-12α, IFN-γ and IL-4, was established very early in the development of E. multilocularis. Subsequently, the profile extended to a combined tolerogenic profile associating IL-5, IL-10 and TGF-β. IL-17 was permanently expressed in the liver, mostly in the periparasitic infiltrate; this was confirmed by the increased mRNA expression of both IL-17A and IL-17F from a very early stage, with a subsequent decrease of IL-17A after this first initial rise. All measured chemokines were significantly expressed at a given stage of infection; their expression paralleled that of the corresponding Th1, Th2 or Th17 cytokines. In addition to giving a comprehensive insight in the time course of cytokines and chemokines in E. multilocularis lesion, this study contributes to identify new targets for possible immune therapy to minimize E. multilocularis-related pathology and to complement the only parasitostatic effect of benzimidazoles in AE.

In patients with AE liver lesions, the absence of microcysts on MRI is strongly correlated to a metabolically inactive disease.

We report the 30-yr history of a well-documented human case of alveolar echinococcosis, with a lung lesion at presentation followed by the discovery of a liver lesion, both removed by surgery. Subsequently, within the 13 years following diagnosis, metastases were disclosed in eye, brain and skull, as well as additional lung lesions. This patient had no immune suppression, and did not have the genetic background known to predispose to severe alveolar echinococcosis; it may thus be hypothesized that iterative multi-organ involvement was mostly due to the poor adherence to benzimidazole treatment for the first decade after diagnosis. Conversely, after a new alveolar echinococcosis recurrence was found in the right lung in 1994, the patient accepted to take albendazole continuously at the right dosage. After serology became negative and a fluoro-deoxy-glucose-Positron Emission Tomography performed in 2005 showed a total regression of the lesions in all organs, albendazole treatment could be definitively withdrawn. In 2011, the fluoro-deoxy-glucose-Positron Emission Tomography showed a total absence of parasitic metabolic activity and the patient had no clinical symptoms related to alveolar echinococcosis.The history of this patient suggests that multi-organ involvement and alveolar echinococcosis recurrence over time may occur in non-immune suppressed patients despite an apparently “radical” surgery. Metastatic dissemination might be favored by a poor adherence to chemotherapy. Combined surgery and continuous administration of albendazole at high dosage may allow alveolar echinococcosis patients to survive more than 30 years after diagnosis despite multi-organ involvement.

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