Immunoperoxidase staining of alveolar hydatid cyst from an experimentally infected gerbil.

Echinococcus multilocularis, the small fox tapeworm, has an extensive geographical range in the northern hemisphere where foxes and small rodents represent natural hosts. The larval stage of this parasite, alveolar echinococcosis (AE), is an emerging zoonosis of increasing importance. It is a serious human illness which is often misdiagnosed as hepatic cancer. If not identified at an early stage of parasite development it can lead to the death of patients. Histological examination of biopsies is one of the classical methods of diagnosis. In this study, in order to gain unequivocal histopathological diagnosis of AE, the immunoperoxidase staining technique was performed on routinely processed histological sections of an experimentally infected gerbil, using rabbit anti-E. multilocularis protoscolex IgG labelled with horseradish peroxidase. Demonstration of AE antigen was achieved by dark brown stain of cyst membranes against a blue background of the host liver cells stained with hematoxylin.