Impact of Anisakis pegreffi Infection on Gonadal Health and Gonadosomatic Index of European Hake (Merluccius merluccius)

Parameters belonging to the physical status and gonadal size of certain fish provide crucial information for assessing both the productivity and fecundity of declining fish populations. These parameters are vulnerable to the negative impacts of disease agents such as internal or systemic parasites. Although parasitic diseases might influence these parameters, the literature investigating these pathophysiological alterations is scanty. Therefore, the current study represents one of the scarcest studies that document the possible link between parasitism, gonadal health, and the growth of European hake (Merluccius merluccius). Screening of imported European halves indicated a relatively high prevalence of Anisakis pegreffi Larvae 3 infestation, with an 80% prevalence rate, a mean intensity of 24.4, and a mean abundance of 19.5. However, the prevalence of Anisakid larvae infection in native fish was 36% with a mean intensity of 7.36 and mean abundance of 2.65.The current research revealed remarkable ovarian pathology that involved several forms of degenerative changes in ovarian tissues. Such gonadal pathologies were attributed to the damaging effect of the retrieved Anisakis pegreffi Larvae 3. Gonadosomatic index of both heavily infected imported / native hakes was relatively impacted by the progressive gonadal pathology resulting from Anisakis pegreffi L3 infection. Morphometric measurements of the gonads and body have revealed that, gonadosomatic index of both heavily infected imported / native hakes was relatively impacted by the progressive gonadal pathology resulting from Anisakis pegreffi L3 infection

Streptococcus dysgalactiae: An emerging pathogen of fishes and mammals

Streptococcus dysgalactiae subsp. dysgalactiae (GCSD) has gained special interest of aquatic health experts throughout the past few years due to its interesting veterinary and public health importance. Increasing records of GCSD infections in farmed fishes have been documented through diverse worldwide aquatic habitats in Japan, China, Malaysia, Indonesia, Taiwan and Brazil. Despite the intraspecies/interspecies dynamic spread of fish GCSD, yet, the genetic basis of its virulence remains unknown. This gap in knowledge is the main reason behind inability to develop a competent vaccine to control the disease in aquatic animals. However, the authors have concluded that the virulence of GCSD is mainly based on its cell surface properties such as high hemagglutination and hydrophobic properties which determine the main adhesive/invasive pathogenic mechanism of the pathogen where GCSD isolates were able to adhere to and invade fish epithelial cell line in vitro. Most recently, the molecular pathogenesis investigations have revealed that, serum opacity factor [SOF], superantigen and streptolysin S genes might be the most important virulence factors that have contributed to the swift propagation of streptococcal infection among aquatic and mammalian species. In conclusion, the current research based review has emphasized the current knowledge gap in epidemiology and control of fish GCSD. To bridge this current gap, a swift future development of high tech/accurate molecular research is highly needed to better understand the pathogenic mechanisms of GCSD

Detection of Saprolegnia parasitica in eggs of angelfish Pterophyllum scalare (Cuvier–Valenciennes) with a history of decreased hatchability

Mass mortalities of angelfish eggs accompanied with very low hatchability were reported in a private ornamental fish farm in Egypt. Examined eggs were badly damaged by water mould that was decisively confirmed as Saprolegnia species. Presumptive identification of the ten retrieved isolates was initially suggestive of Saprolegnia species. Mycological investigations have revealed that only 7 out of 10 isolates were capable of producing sexual stages. Therefore, using molecular tools such as PCR coupled with partial sequencing of inter-transcribed spacer (ITS) gene was one of the most important approaches to distinguish Saprolegnia parasitica from other water moulds. The sequences of ITS gene data derived from eight isolates showed 100% similarity with S. parasitica ATCC90312 sequence and the remaining two isolates were different in one nucleotide (99.9%). The phylogenetic analysis of ITS genes grouped the ten isolates with other S. parasitica in one clad. Further, to control such fungal infection, the efficacy of povidone iodine as surface disinfectant for angelfish and their fertilized eggs were tested. By trial, it was obvious that the obtained post-rinsing results were highly suggestive for the efficacy of povidone iodine as an efficient antifungal disinfectant for both fish and eggs

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

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

Chitosan nanoparticles and green synthesized silver nanoparticles as novel alternatives to antibiotics for preventing A. hydrophila subsp. hydrophila infection in Nile tilapia, Oreochromis niloticus

ABSTRACTRecently, nanoparticles have attracted attention as a preventive tool for certain infectious diseases affecting fish in aquaculture. Furthermore, freshwater fishes are frequently vulnerable to summer mass morality caused by Aeromonas bacteria. In this regard, we focused on the evaluation of the in vitro and in vivo antimicrobial activity of chitosan (CNPs) and silver (AgNPs) nanoparticles against Aeromonas hydrophila subsp. hydrophila. CNPs and AgNPs were prepared at a mean particle size of 9.03 and 12.8 nm and a charge equalled+36.4 and −19.3 mV for CNPs and AgNPs, respectively. A. hydrophila subsp. hydrophila, Aeromonas caviae, and Aeromonas punctata were retrieved and identified by traditional and molecular techniques. The sensitivity of the obtained bacteria to eight different antibiotic discs was also tested. The antibiotic sensitivity studies revealed the presence of multidrug-resistant (MDR) Aeromonas species (spp.). The bacterium that showed the highest multidrug resistance against the tested antibiotic discs was Aeromonas hydrophila subsp. hydrophila. Therefore, CNPs and AgNPs were in vitro tested against the isolated bacterium and exhibited inhibition zones of 15 and 25 mm, respectively. TEM images also showed that CNPs and AgNPs had an antagonistic action against the same bacterium causing loss of architecture and bacterial death