Differentiation of Cerebral Cystic Echinococcosis (CCE) from Coenurosis Using Morphometric and Molecular Methods

Cerebral cystic echinococcosis (CCE) and coenurosis are zoonotic diseases caused by the larval stages of Echinococcus granulosus sensu lato (s.l.) and Taenia spp., respectively. Due to the similarity between the symptoms and clinical samples of CCE and cerebral coenurosis, especially in cases with no protoscoleces, the diagnostic methods for the differentiation of CCE from cerebral coenurosis are crucial, especially in countries where both diseases are endemic. To compare CCE and coenurosis, morphometric indices of protoscoleces and molecular methods were used in the present study.

In this regard, four isolates of human cerebral echinococcal cysts, three isolates of Coenurus cerebralis from sheep, and one non-cerebral Coenurus from sheep muscles were evaluated. The isolated specimens have been collected from Shiraz, Ahvaz, Tehran and Kerman from before 2000 to 2022. The molecular characterization was carried out using the partial NADH dehydrogenase1 (nad1) gene. Phylogenetic analysis was performed using the maximum likelihood method.

In fertile cysts, the total size of the large and small hooks of Coenurus was larger than cerebral echinococcal cyst. These parameters demonstrated significant morphological differences between the C. cerebralis and the cerebral echinococcal cyst. Molecular methods identified the cerebral echinococcal cysts as E. canadensis (G6) genotype. One C. cerebralis and the non-cerebral Coenurus were identified as Taenia multiceps and T. multiceps gaigeri, respectively.

Morphometric indices are significantly different between protoscoleces of C. cerebralis and cerebral echinococcal cysts. Hence, they could be used for differential diagnosis of the fertile cysts of these cestodes. However, in cases with no protoscoleces, molecular methods are essential for the differentiation of CCE from cerebral coenurosis, especially in regions where both diseases are prevalent and endemic.