Ligula intestinalis in Labeobarbus fish species at Lake Tana, Ethiopia: prevalence, histopathological investigation, and associated risk factors.

Abstract

Food security and employment prospects are significantly influenced 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 L. intestinalis infection in Labeobarbus fish species in Lake Tana, Ethiopia. A total of 384 Labeobarbus fish were randomly selected from local fishermen and their associations. Pathological lesions were examined using proper evisceration and post-mortem techniques. Various visceral organs including the gonads, liver, and spleen were collected from infected fish for histopathological examination. Gross pathological findings revealed abdominal distension, anal hemorrhage, and gonadal atrophy, displacement of internal organs, body emaciation, and visceral fibrosis accompanied by discoloration. Histopathological alterations were observed in multiple organs. In the ovaries, the main changes included fibrosis, infiltration of inflammatory cells, destruction, and atrophy of oocytes. Testicular tissues exhibited hyperemia, necrosis, fibrosis, and degeneration. The liver showed vacuolar degeneration, biliary duct hyperplasia, infiltration of inflammatory cells, fibrosis, and necrosis. In the spleen, exudation, hemorrhage, congestion, and fibrosis were the primary pathological findings. Out of the 384 Labeobarbus fish examined, 62 tested positive for L. intestinalis, indicating an overall prevalence of 16.2% in Lake Tana. Statistical analysis revealed that 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 L. intestinalis infection. The pathological effects of L. intestinalis on vital organs, combined with its high prevalence, suggest a significant negative impact on fish production and reproductive performance in Lake Tana. Therefore, regular monitoring and surveillance, public awareness campaigns, ecological studies, and appropriate policy interventions should be implemented to protect livelihoods and mitigate the effects of this parasite.