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Abstract

Aquaculture sector in Egypt has demonstrated a remarkable development; however, it has also faced challenges with respect to disease outbreaks. Nile tilapia is the most widely cultured species in Egypt. Under stress conditions, tilapia is vulnerable to a variety of bacterial diseases that tend to be ubiquitous in the freshwater environment. Semi-intensive Nile tilapia farms in Kafr El-Sheikh Governorate, Egypt are experiencing acute mortality especially during summer months. The samples from these farms were collected and subjected to investigations to identify the etiological agent(s) behind these mortalities. Bacteriological examination revealed that the dominant bacteria were Gram-negative rods and identified as Aeromonas spp. through biochemical tests. PCR, restriction fragment length polymorphism (RFLP) assays, and sequencing confirmed the presence of Aeromonas hydrophila. In addition, the aerA gene, a virulence factor in A. hydrophila, was detected by PCR in all identified A. hydrophila isolates. In order to confirm that the isolated A. hydrophila was the causative agent of tilapia mortality, healthy Nile tilapia were challenged with the isolated strains, which produced the same clinical picture of the collected samples. This study implicates that A. hydrophila could be the causative agent of the summer mortality in Nile tilapia farms in Kafr El-Sheikh Governorate, Egypt.

Natural co‐infection of cultured Nile tilapiaOreochromis niloticuswithAeromonas hydrophilaandGyrodactylus cichlidarumexperiencing high mortality during summer

“…Aeromonas sp. is one of the main bacterial problems facing the growth of aquaculture in Egypt, where it causes mass mortalities and a significant reduction in the production rates (Eissa et al, 2010;Elsheshtawy et al, 2019). In the current study, the clinical signs and post-mortem lesions of the diseased tilapia showed typical signs of septicaemia that include deep dermal ulceration, reddening of the skin, abdominal dropsy and abraded fins and protruded haemorrhagic anal opening.…”

“…In Egypt, A. hydrophila is a predominant bacterium in warm water aquaculture, which causing high mortalities even without symptoms in the per-acute phase. However, in the acute phase, skin and fin ulcers with ascites and exophthalmia were the most reported lesions that causing significant economic losses in aquaculture industry due to low survival rate of the cured fish (Dahdouh, Basha, Khalil, & Tanekhy, 2016;Elsheshtawy, Yehia, Elkemary, & Soliman, 2019).…”

Molecular characterization of Aeromonas hydrophila isolates from diseased fishes in district Kasur, Punjab, Pakistan

“…Despite the fact that the aquaculture sector is facing many challenges with respect to bacterial diseases all around the world and these diseases have a negative impact on the economic affluence of aquaculture fields; still very less determination is observed towards focusing on this aspect of the field (Elsheshtawy et al, 2019).…”

Prevalence of Aeromonas species in Clarias gariepinus and water from different culture facilities in fish farms in Kwara State, Nigeria

“…However, the challenges due to the presence of pathogenic organisms especially bacteria, have limited its effective production and availability of a readily cheap source of protein (Afolabi, et al, 2020). Disease at any stage of the fish culture is a significant setback that usually leads to great consequences on the economic viability of fish farms and on the yield of protein for human consumption (Tavares-Dias & Martins, 2017;Elsheshtawy, et al, 2019). Gram-negative bacteria like Aeromonas species are the most common causes of morbidity and mortality leading to great economic losses in the aquaculture industry (Mailafia et al, 2021;Pepi & Focardi, 2021).…”