Prevalence of Ligula intestinalis, histopathological investigation, and associated risk factors in Labeobarbus fish species at Lake Tana, Ethiopia

Food security and employment prospects are significantly impacted by the fish industry. A cross-sectional study was conducted from February 2023 to March 2024 to determine the pathological lesions, prevalence, and associated risk factors of Ligula intestinalis on Labeobarbus fish species in Lake Tana, Ethiopia. A total of 384 Labeobarbus fish were randomly selected from the fishermen and their associations. The pathological lesions were examined using proper evisceration and post-mortem techniques. Various visceral organs, including the gonads (testes and ovaries), liver, and spleen, were collected from infected fish for histopathological examination. Gross pathological findings revealed abdominal distension, anal hemorrhage, gonads atrophy, displacement of internal organs, body emaciation, and visceral fibrosis accompanied by discoloration. Histopathological changes were observed in various organs, including the ovaries, testes, liver, and spleen. In the ovaries, the major alterations included fibrosis, infiltration of inflammatory cells, destruction, and atrophy of oocytes. In the testicular tissue, hyperemia, necrosis, fibrosis, and degeneration were detected. In the liver, vacuolar degeneration, biliary duct hyperplasia, infiltration of inflammatory cells, fibrosis, and necrosis were observed. In the spleen, exudation, hemorrhage, congestion, and fibrosis were the primary pathological alterations and deformities identified in the study. Among the total Labeobarbus fish included in this study, 62 were positive for Ligula intestinalis, indicating an overall parasite prevalence of 16.2% in Lake Tana. Fish standard length (χ² = 76.919, P = 0.001), fish weight (χ² = 50.087, P = 0.001), sampling points (χ² = 16.947, P = 0.009), and fish species (χ² = 27.73, P = 0.034) were significantly associated with Ligula intestinalis infection in Labeobarbus fish. The pathological effects of this parasite on vital organs, along with its high prevalence, have a significant impact on fish production and reproduction.