Department of Aquatic Animal Medicine and Management, Faculty of Veterinary Medicine, Cairo University, PO 12211, Giza, Egypt.
Department of Parasitology, Faculty of Veterinary Medicine, Cairo University, PO 12211, Giza, Egypt.
Sci Rep. 2024 Sep 5;14(1):20704. doi: 10.1038/s41598-024-70528-x.
This study investigated a disease outbreak characterized by caligid copepod infestations and subsequent secondary bacterial infections in European seabass (Dicentrarchus labrax) and flathead grey mullet (Mugil cephalus) cultivated at a private facility in the Deeba Triangle region of Egypt. Moribund fish displayed brown spots on the skin, tongue, and gills, along with lethargy and excess mucus. The fish suffered severe infections, exhibiting external hemorrhages, ulcers, and ascites. The fish had pale, enlarged livers with hemorrhaging. Comprehensive parasitological, bacteriological, molecular, immunity and histopathological analyses were conducted to identify the etiological agents and pathological changes. Caligid copepod infestation was observed in wet mounts from the buccal and branchial cavities of all examined fish, and the caligids were identified as Caligus clemensi through COI gene sequencing and phylogenetic analysis. Vibrio alginolyticus was confirmed as a secondary bacterial infection through biochemical tests, recA gene sequencing, and phylogenetic analyses. Antibiotic susceptibility testing revealed resistance to β-lactams, aminoglycosides, and trimethoprim-sulfamethoxazole in V. alginolyticus isolates. Upregulation of the inflammatory marker IL-1β in gill and skin tissues indicated a robust cell-mediated immune response against the pathogens. Histopathological examination revealed severe tissue damage, hyperplasia, hemorrhage, and congestion in the gills, along with hepatocellular degeneration and steatosis in the liver, providing initial insights into this outbreak. A comprehensive therapeutic regimen was implemented, comprising prolonged hydrogen peroxide immersion baths, followed by the application of the nature-identical plant-based compound Lice-less and probiotic Sanolife Pro-W supplementation. This integrated approach effectively eliminated C. clemensi infestations, controlled secondary bacterial infections, and restored fish health, reducing morbidity and mortality rates to minimal levels.
本研究调查了埃及迪拜三角地区一家私人养殖场中养殖的欧洲鲈鱼（Dicentrarchus labrax）和棱鳀（Mugil cephalus）爆发的一种疾病，其特征为桡足类桡足动物的侵袭以及随后的继发细菌性感染。濒死的鱼体表、舌和鳃上有棕色斑点，且行动迟缓、黏液过多。鱼患有严重的感染，表现为外部出血、溃疡和腹水。鱼的肝脏苍白、肿大且有出血。通过全面的寄生虫学、细菌学、分子学、免疫学和组织病理学分析，以确定病因和病理变化。在所有检查鱼的口腔和鳃腔的湿载玻片上都观察到桡足类桡足动物的侵袭，通过 COI 基因测序和系统发育分析，鉴定桡足动物为 Caligus clemensi。通过生化试验、recA 基因测序和系统发育分析，确认弧菌属 Alg 为继发性细菌感染。抗生素药敏试验显示，弧菌属 Alg 分离株对β-内酰胺类、氨基糖苷类和甲氧苄啶-磺胺甲恶唑有耐药性。IL-1β在鳃和皮肤组织中的上调表明对病原体存在强烈的细胞介导免疫反应。组织病理学检查显示，鳃组织严重的组织损伤、增生、出血和充血，肝脏肝细胞变性和脂肪变性，为本次疫情提供了初步的见解。实施了综合治疗方案，包括长时间的过氧化氢浸泡浴，然后应用天然植物化合物 Lice-less 和益生菌 Sanolife Pro-W 补充剂。这种综合方法有效地消除了桡足类桡足动物的侵袭，控制了继发性细菌感染，并恢复了鱼类的健康，将发病率和死亡率降低到最低水平。
