Abdel-Aziz, M., A. E. Eissa, M. Hanna, and M. A. Okada, Identifying some pathogenic Vibrio/Photobacterium species during mass mortalities of cultured Gilthead seabream (Sparus aurata) and European seabass (Dicentrarchus labrax) from some Egyptian coastal provinces, , vol. 1, issue 2, pp. 87 - 95, 2013. AbstractWebsite

Vibrio alginolyticus, Vibrio parahemolyticus and Photobacterium damselae subsp damselae were isolated during recurrent episodes of mass mortalities among different stages of Gilthead sea bream (Sparus aurata) and European seabass (Dicentrarchus labrax). The pathogens were recovered from the external/internal lesions of a total of 320 seeds, juvenile and adult fishes from the period of February 2013 through August 2013. Two hundred and sixty four bacterial isolates were retrieved and presumptively identified using morpho-chemical characterization and API®20NE. However, definitive molecular confirmation of V. alginolyticus was obtained through implementing collagenase gene based regular PCR technique. The total prevalence of V. alginolyticus, V. parahemolyticus and Photobacterium damselae subsp damselae among naturally infected Gilthead seabream and European seabass was 82.19%, 87.28% 10.27%, 6.79% and 7.54%, 5.93% respectively. Antibiogram has revealed that isolates were sensitive to ciprofloxacin, chloramphenicol, enrofloxacin, nalidixic acid and oxolinic acid while resistant to ampicillin, amoxicillin, and lincomycin.

Ismail, M., S. Mohammed, A. M. Shams, M. Shahin, A. A. Helal, M. Maged, H. E. Elmorshedy, A. A. Kandeel, M. Ghonim, M. Abou-Okada, et al., Needlescopic lymphatic-sparing varicocelectomy in children using a mediflex needle: a new simplified technique, , vol. 2, issue 2, pp. 75 - 81, 2020. AbstractWebsite

In this study we present a new technique for Needlescopic dye-assisted lymphatic-sparing Varicocelectomy (NV) in children using 14-gauge fascial closure needles (Mediflex ®, D-1001 New York, USA), (MedN) and a Vascular Access Canula (VAC).

Abou-Okada, M., N. M. El-Gendy, and R. Elhelw, "Effect of booster vaccination on immunoprotection in European seabass vaccinated against vibriosis", Aquaculture ResearchAquaculture Research, vol. 52, issue 2: John Wiley & Sons, Ltd, pp. 736 - 748, 2021. AbstractWebsite

Abstract In farmed saltwater fish, vaccination is considered the first barrier against pathogenic agents. In Egypt, the vaccine application can diminish the dilemma of summer mass kills of farmed marine fish. The efficacy of booster vaccination with a bivalent vaccine against vibriosis was studied in European seabass. Fish were vaccinated by direct immersion (DI) in water containing bivalent Vibrio alginolyticus and Vibrio parahemolyticus whole cells killed vaccine. Immersion vaccination is more applicable under semi-intensive fish culture, but less potent than injection. Accordingly, to increase antigen uptake and conferred protection, vaccinated fish randomly received booster vaccination via direct immersion (DI imm.) or intraperitoneal injection (i.p.) at 21 days post-prime vaccination (21 dpv). Vaccinated and unvaccinated fish were monitored for 3 months and challenged with V. alginolyticus and/or V. parahemolyticus at 42 dpv. Specific and non-specific immune responses were evaluated in blood samples. At 52 dpv (10 days post-challenge), the relative immunoglobulin T (IgT) expression was assessed in the gills, hindgut, head kidney and spleen. Notably, imm. + imm. and imm. + i.p. vaccination yielded significantly higher specific antibody titre at 70 dpv, whereas the former was associated with significantly higher IgT expression in the gills and hindgut (p < .05) than the latter. High IgT levels in mucosal organs (gills and hindgut) might be the first indicator of the involvement of IgT in mucosal immune responses. Relative per cent survival among booster-vaccinated fish ranged from 70% to 90%. The results support the use of this vaccination protocol as a highly effective tool to protect seabass from vibriosis and to improve fish health and environment. Booster doses are strongly recommended under farming environments.

W. Soliman, A., and et al, Molecular detection of the most common bacterial pathogens affecting economically important Egyptian Red Sea fishes, , vol. 25, issue 4, pp. 669 - 688, 2021. AbstractWebsite

The current study aimed to investigate the most common pathogenic bacteria that are naturally infecting wild marine fishes collected at different localities along the coastline zone of Hurghada City, Egypt. A total of 300 samples of marbled spine foot Siganus rivulatus and the Haffara Seabream Rhabdosargus haffara were subjected to clinical and bacteriological examinations. The examined fishes showed the characteristic clinical signs and postmortem lesions of vibriosis and photobacteriosis. Based on the morpho-chemical characterization, bacterial isolates retrieved from the naturally infected fishes were identified as Vibrio spp. and Photobacterium spp. Through sequencing 16S rRNA genes, the identities of bacterial isolates were confirmed as V. alginolyticus, V. vulnificus, P. damselae subsp. damselae and P. damselae subsp < em> piscicida. Vibrio alginolyticus was the most frequent isolated bacterial pathogen and represented 54.4% and 46.7% of the total isolates recovered from S. rivulatus and R. haffara, respectively. Thus, the current study confirmed that Vibrio and Photobacterium species remain the most prevalent bacterial pathogens infecting Egyptian Red Sea fishes.  From food safety perspective, these types of infections could pose potential public health hazards.

A. Abdelbaky, A., and et al, Genotypic characterization of some dermotropic and systemic bacterial pathogens affecting two commercial Red Sea fishes, , vol. 25, issue 6, pp. 297 - 312, 2021. AbstractWebsite

The genotypic characterization of some bacterial pathogens that were incriminated in disease outbreaks among Haffara seabream “Rhabdosargus haffara” and marbled spine foot “Siganus rivulatus” was investigated in full through the current study. A total of 250 fish samples (125 of each species) were collected along the Red Sea coasts of Hurghada City, Egypt. Fish samples were inspected for clinical signs, post-mortem changes, and bacteriological examination. The investigated fishes displayed septicemic signs and external skin lesions characteristic of streptococcosis and tenacibaculosis. Enterococcus spp., Streptococcus spp., and Flavobacterium spp. were isolated from moribund fishes using selective media. These isolates were phenotypically and genetically identified and characterized. The identities of bacterial isolates were confirmed as Enterococcus fecalis, Streptococcus iniae, Enterobacter cloacae, and Tenacibaculum maritimum based on sequencing the 16S rRNA gene. Enterococcus fecalis was the most common pathogen isolated from S. rivulatus and R. haffara and accounted for 46.8% and 47.8% of the total isolates, respectively. Accordingly, the present study proved that Enterocoocus spp., Streptococcus spp., and T. maritimum are important pathogenic bacteria incriminated in wild fish outbreaks in the Red Sea in Egypt. These findings proved the importance of regular and permanent bacteriological examination of wild fish to overcome fish mortalities, which lead to economic losses. Finally, sequencing and phylogenetic relationship techniques proved their usefulness as an ideal assay to develop a reliable, accurate, and rapid detection method for bacterial pathogens in the aquatic environment.

Attia, M. M., M. Abou-Okada, M. S. M. Shamseldean, and S. M. El-Gameel, Insecticidal effects of Curcumin (Curcuma longa) against the horse stomach bot fly, Gasterophilus intestinalis (Diptera: Oestridae), , vol. 42, issue 1, pp. 917 - 926, 2022. AbstractWebsite

Stomach horse bots (Gasterophilus intestinalis larvae; Diptera: Oestridae) are obligatory parasites inhabit the stomach of domestic Equidae. Colonization of Gasterophilus intestinalis larvae cause funnel-shaped stomach ulcers, sub-serosal abscess, and peritonitis. In the current research work, 3rd instar larvae of G. intestinalis were exposed to different concentrations (5, 10, 20, 40, 80 and 100 ppm) of curcumin from turmeric plant root (Curcuma longa). Survival of insect larvae, their morphological characterization, growth regulation, enzymatic assay and comet assay were assessed. Curcumin exhibited time and concentration dependent insecticidal effect on survival of 3rd instar larvae of G. intestinalis (bot flies). The aqueous extract of curcumin was highly toxic to G. intestinalis larvae with LC50 value of 16.92 ppm after 24 h. The mean comet tail length (µm) and tail moment (µm) at the highest curcumin concentration of 100 ppm were 16.03 ± 0.15 and 3.03 ± 0.09 µm, whereas DNA damage percent was 14.77 ± 0.12%. Further, remarkable inhibition of Glutathione S-transferases (GST) and Acetylcholinesterase (AChE) enzymatic activity were detected. Aqueous extract of curcumin exhibited potent lethal effects to the 3rd instar larvae of G. intestinalis, therefore, it could be used as an active and harmless natural insecticidal to control bot flies’ larvae in donkeys.

Eissa, A. E., M. Abou-Okada, A. R. M. Alkurdi, R. A. El Zlitne, A. Prince, M. Abdelsalam, and H. I. M. Derwa, "Catastrophic mass mortalities caused by Photobacterium damselae affecting farmed marine fish from Deeba Triangle, Egypt", Aquaculture Research, vol. 52, no. 9, pp. 4455-4466, 2021. AbstractWebsite

Abstract Farmed marine fish constitute 20% of the total farmed fish production in Egypt, and the Deeba Triangle produces a relatively large portion of this percentage. Last year, several private fish farms in the Deeba Triangle have suffered severe economic losses due to acute fish mass kills. This study aimed to investigate the hidden aetiologies behind these colossal mass fish kills and to propose an emergency control strategy. Several tons of dead farmed fish were remarkably scattered throughout affected ponds and at the vicinity of impacted fish farms. Moribund farmed European seabass (Dicentrarchus labrax), thin-lipped grey mullet (Liza ramada) and gilthead seabream (Sparus aurata) have exhibited skin darkness, emaciation, congested gills and fins, ascites, skin erosions and ulcerations. Internally, moribund fish emitted unpleasant odour upon opening the abdomen together with severe congestion and haemorrhages in kidneys and brain. Mottled atrophied spleens were the most prominent findings, while the gastrointestinal tracts were filled with whitish caseous material. The liver was pale with multiple whitish nodules. Photobacterium damselae was the most retrievable bacterial pathogen from most infected fish and trash fish. Photobacterium damselae subspecies piscicida and Photobacterium damselae subspecies damselae were definitively identified from examined moribund fish using both conventional morpho-chemical and molecular assays. Data analysis has revealed that the poor water quality was profoundly incriminated in triggering the bacterial infections with a fate of mass mortalities. Conclusively, adopting various strict biosecurity strategies will be the key factors in prevention of future episodes of mass kills.

Abou-Okada, M., H. O. AbuBakr, A. Hassan, S. H. I. M. A. A. ABDEL-RADI, S. H. Aljuaydi, M. Abdelsalam, E. Taha, N. A. Younis, and D. A. Abdel-moneam, "Efficacy of Acriflavine for controlling parasitic diseases in farmed Nile tilapia with emphasis on fish health, gene expression analysis, oxidative stress, and histopathological alterations", Aquaculture, vol. 541, pp. 736791, 2021. AbstractWebsite

Parasites often cause serious outbreaks of disease in farmed fish. The present study is the first to describe the antiparasitic efficacy of Acriflavine on Oreochromis niloticus parasitized with Centrocestus formosanus metacercariae and Trichodina centrostrigeata protozoa. A total of 550 O. niloticus suffering from respiratory distress were collected from a fish farm. Clinical and parasitological examinations of 150 fish revealed a mixed infestation with Centrocestus formosanus and Trichodina centrostrigeata. The median lethal dose (LC50) of Acriflavine (5, 10, 25, 50, & 100 mg/L) was calculated against 160 healthy O. niloticus. Results revealed that the 12 h and 96 h LC50 of Acriflavine was 114.61 and 35.196 mg/L. Further, an experimental design consisting of three fish groups was used to assess the efficacy of Acriflavine (10 mg/L, long-term bath) against Centrocestus formosanus- and Trichodina centrostrigeata-infested fish; the first group was treated with Acriflavine (treated fish), the second group was not treated (nontreated fish) and the third group was healthy fish (negative control). Acriflavine was effective against Centrocestus formosanus and Trichodina centrostrigeata, reducing the mean intensity of parasites by 91.1% and 95.6%, respectively, compared with infested fish (nontreated). Moreover, treated fish exhibited restoration of normal gill histoarchitecture and normal central cartilaginous support after treatment. Treated O. niloticus also showed significant downregulation of inflammatory-related enzyme (Cox-2) and pro-inflammatory cytokine (IL-1ß) genes compared with infested fish, as well as a significant reduction in lipid peroxidation (LPO) levels. Acriflavine provides a safe and efficient treatment for controlling Centrocestus formosanus metacercariae and Trichodina centrostrigeata protozoans, improving the health, productivity and welfare of Oreochromis niloticus.