A Study on the Pathological Effects of Trypanorhyncha Cestodes in Dusky Groupers Epinephelus marginatus from the Canary Islands

Abstract

Trypanorhyncha are cestodes commonly infecting marine fish. Numerous studies have detailed the biology of Trypanorhyncha species, but information on the pathological changes produced by these parasites is limited. Dusky groupers are keystone species necessary for the preservation of several marine ecosystems. Considering their vulnerable state of conservation and the efforts being made to culture them, identification of the effects caused by Trypanorhyncha is vital. Here, we aimed to determine the prevalence and pathological changes produced by Trypanorhyncha in dusky groupers from the Canary Islands. The prevalence of trypanorhynch plerocerci was 96%. Grossly, in the abdominal cavity, there were numerous larvae-filled cysts and nodules. These were embedded in abundant fibrosis, producing visceral adhesions. Histologically, affecting the peritoneum, stomach, and intestine there were numerous degenerated encysted plerocerci and extensive deposition of mature connective tissue. These findings indicate that Trypanorhyncha is highly prevalent in adult dusky groupers from the Canary Islands, producing a progressive and chronic response. Furthermore, fish immune system appears to attempt to eliminate the parasites through fibrous encapsulation. Nonetheless, extensive fibrosis may have a detrimental impact on fish health when adjacent cells or tissues are compressed and their functions impaired.

Larvae trypanorhynch (Cestoda) infecting the dusky flounder, Syacium papillosum (Paralichthyidae: Pleuronectiformes) in the continental shelf of the Yucatan Peninsula, Mexico

“…Trypanorhynch species ( Callitetrarhynchus gracilis (Rudolphi, 1819) Pintner, 1931, Floriceps sp., Pintneriella musculicola Yamaguti, 1934 ) can generate injuries in fish, however, information regarding the pathological changes caused by these parasites is still limited. In visceral organs and musculature of marine teleosts histopathological changes are observed including necrosis, inflammatory, and fibrosis ( Ibrahim, 2000 ; Hassan et al ., 2002 ; Abdelsalam et al ., 2016 ; Sales-Ribeiro et al ., 2021 ). Molecular analysis supports the presence of Oncomegas wageneri belonging to the Eutetrarhynchid genus.…”

“…The benthic habits of flatfish make them susceptible to parasitic infections, mainly of trypanorhynch larvae. In high intensity of infection, the plerocercoids cysts adhere to the serosal surfaces of the abdominal organs and invade the muscle and the submucosa of the stomach and intestine, which cause fish disorders such as inflammatory reaction, fibrosis and necrosis ( Hassan et al ., 2002 ; Sales-Ribeiro et al ., 2021 ). Epinephelus aerolatus with heavy infection of Floriceps sp.…”

Infection of endemic chub Squalius tenellus with the intestinal tapeworm Caryophyllaeus brachycollis (Cestoda): histopathology and ultrastructural surveys

“…Numerous studies have documented that the presence and action of the enteric helminths in fish recruit different types of inflammatory cells belong to the innate immune system, as well as a network of nervous fibres at the site of infection (Dezfuli et al ., 2016; de Sales-Ribeiro et al ., 2021; Bosi et al ., 2022). Herein, in the S. tenellus – C. brachycollis system occurrence of mucous cells, RCs, MCs, neutrophils and MAs was documented.…”