Morpho-molecular identification of Heterophyes heterophyes encysted metacercariae and its immunological and histopathological effects on farmed Mugil cephalus in Egypt

Molecular and immunological aspects of heterophyid infections in mullets are scanty. This study was initiated to identify heterophyid encysted metacercariae infecting gray mullet Mugil cephalus by morphological and molecular assays and to evaluate its immunological effects on infected mullets. Both farmed fish, from a private farm nearby Lake Manzala in Damietta, Egypt, and wild-caught fish, from the Mediterranean Sea in Alexandria, were investigated. The presence of heterophyid encysted metacercariae was significantly higher (80%) in wild than in farmed fish (30%). Morphological identification of metacercariae showed characteristic features of H. heterophyes. The result of sequences of 28S and ITS2 rDNA regions of Heterophyes EMC was consistent with the morphological data. The gene expression analysis of tumor necrosis factor alpha (TNF-alpha) and interleukin-10 (IL-10) in tissues of infected fish qRT-PCR showed a significant increase (p < 0.05). Encysted metacercariae were detected microscopically in sections of infected fish with variable histopathological lesions.

Automated summary

This study identified heterophyid encysted metacercariae infecting gray mullets through morphological and molecular assays, showing a higher prevalence in wild-caught fish compared to farmed fish. Gene expression analysis indicated a significant increase in TNF-alpha and IL-10 in infected fish tissues, along with variable histopathological lesions in infected fish sections.