Systemic Pathological Disorders in Juvenile Rainbow Trout (Oncorhynchus mykiss) During Ichthyophthiriosis (Ichthyophthirius multifiliis) Infestation

The article presents the results of a comprehensive study of systemic pathological disorders in young rainbow trout (Oncorhynchus mykiss) under spontaneous infestation with Ichthyophthirius multifiliis. The study included clinical examination, parasitological, microbiological, haematological, biochemical and histological analyses. The intensity of invasion (II) of ichthyophthiriosis was 7.0 ± 3.4 examples per microscopic field (body surface) and 24 ± 8.9 examples per microscopic field (gills). [Or define your abbreviation]. A complex of Gram-negative bacteria was isolated from the liver of infected fish: Enterobacter sp. (20%), Citrobacter freundii (60%), Acinetobacter calcoaceticus (20%), indicating the development of secondary bacterial infection. Haematological analysis revealed a decrease in erythrocyte count to 1.05 ± 0.06 x 106 cells/µL and an increase in leucocyte count to 3.87 ± ± 0.51 x 104 cells/µL, with a relative neutrophilia (38.45 ± 0.97%). Serum biochemical analysis showed a significant increase in AST activity (750.9 ± 147.7 U/L), ALT (39.4 ± 6.7 U/L), alkaline phosphatase (467.8 ± 72.6 U/L), LDH (2557.3 ± 245.1 U/L), total protein (43.83 ± 5.31 g/L), albumin (24.12 ± 2.2 g/L) and glucose (3.11 ± 0.13 µmol/L), and urea (3.23 ± 0.62 µmol/L) concentrations. Histological analysis revealed damage to the gill epithelium, degradation of renal tubules, vacuolisation and necrosis of hepatocytes, and hypotrophy of reticuloendothelial cells of the spleen. The obtained data indicate that ichthyophthyriasis is a systemic disease leading to multi-organ disorders in rainbow trout and manifests as an associative protozoalbacterial disease.

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