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Parasite. 2014;21:63. doi: 10.1051/parasite/2014063. Epub 2014 Nov 28.

Echinococcus metacestode: in search of viability markers.

Author information

1
Institute of Parasitology, Vetsuisse Faculty and Faculty of Medicine, University of Bern, Switzerland.
2
Institute of Parasitology, Vetsuisse Faculty and Faculty of Medicine, University of Bern, Switzerland - WHO-Collaborating Centre for the Prevention and Treatment of Human Echinococcosis, University of Franche-Comté and University Hospital, Besançon, Franche-Comté, France.
3
Department of Nuclear Medicine, University of Franche-Comté and Jean Minjoz University Hospital, Besançon, Franche-Comté, France - WHO-Collaborating Centre for the Prevention and Treatment of Human Echinococcosis, University of Franche-Comté and University Hospital, Besançon, Franche-Comté, France.
4
Laboratory of Parasitology-Mycology, Centre Hospitalier Universitaire, Université de Franche Comté, Besançon, France - WHO-Collaborating Centre for the Prevention and Treatment of Human Echinococcosis, University of Franche-Comté and University Hospital, Besançon, Franche-Comté, France.
5
WHO-Collaborating Centre for the Prevention and Treatment of Human Echinococcosis, University of Franche-Comté and University Hospital, Besançon, Franche-Comté, France.

Abstract

Epidemiological studies have demonstrated that most humans infected with Echinococcus spp. exhibit resistance to disease. When infection leads to disease, the parasite is partially controlled by host immunity: in case of immunocompetence, the normal alveolar echinococcosis (AE) or cystic echinococcosis (CE) situation, the metacestode grows slowly, and first clinical signs appear years after infection; in case of impaired immunity (AIDS; other immunodeficiencies), uncontrolled proliferation of the metacestode leads to rapidly progressing disease. Assessing Echinococcus multilocularis viability in vivo following therapeutic interventions in AE patients may be of tremendous benefit when compared with the invasive procedures used to perform biopsies. Current options are F18-fluorodeoxyglucose-positron emission tomography (FDG-PET), which visualizes periparasitic inflammation due to the metabolic activity of the metacestode, and measurement of antibodies against recEm18, a viability-associated protein, that rapidly regresses upon metacestode inactivation. For Echinococcus granulosus, similar prognosis-associated follow-up parameters are still lacking but a few candidates may be listed. Other possible markers include functional and diffusion-weighted Magnetic Resonance Imaging (MRI), and measurement of products from the parasite (circulating antigens or DNA), and from the host (inflammation markers, cytokines, or chemokines). Even though some of them have been promising in pilot studies, none has been properly validated in an appropriate number of patients until now to be recommended for further use in clinical settings. There is therefore still a need to develop reliable tools for improved viability assessment to provide the sufficient information needed to reliably withdraw anti-parasite benzimidazole chemotherapy, and a basis for the development of new alternative therapeutic tools.

PMID:
25429386
PMCID:
PMC4245873
DOI:
10.1051/parasite/2014063
[Indexed for MEDLINE]
Free PMC Article

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