Journal of aquatic animal health最新文献

Tilapia culture is a very promising industry within the aquaculture sector. However, disease outbreaks have continued to threaten the industry, causing serious economic losses among the producers. Streptococcosis has become the major bacterial disease affecting tilapia production in most regions of the world. To combat the disease and minimize its economic impact on fish producers, numerous preventive and control measures have been developed and reported over the years. This paper aims to systematically review the measures that could be used to manage the disease outbreaks and maintain fish health based on previously published scientific studies. Although numerous measures currently available have been highlighted, it is far better for the producers to maximize the preventive measures for management to be economically feasible. Among the currently available preventive measures, the use of vaccines has been shown to have the most promise, while the use of herbs has been demonstrated to be a more sustainable and economically affordable control measure. However, there are still a number of important gaps in existing literature that require further investigation. Overall, significant progress has been made in preventing and controlling streptococcosis in tilapia although, no single effective measure has been identified. Therefore, a combination of these measures may provide a more effective result.

One of the major goals in aquaculture is to protect fish against infectious diseases as disease outbreaks could lead to economic losses if not controlled. Antimicrobial peptides (AMPs), a class of highly conserved peptides known to possess direct antimicrobial activities against invading pathogens, were evaluated for their ability to protect Channel Catfish Ictalurus punctatus and hybrid catfish (female Channel Catfish × male Blue Catfish I. furcatus) against infection caused by the fish pathogen Aeromonas hydrophila ML09-119. To identify effective peptides, the minimum inhibitory concentrations against bacterial pathogens Edwardsiella ictaluri S97-773, Edwardsiella piscicida E22-10, A. hydrophila ML09-119, Aeromonas veronii 03X03876, and Flavobacterium columnare GL-001 were determined in vitro. In general and overall, cathelicidins derived from alligator and sea snake exhibited more potent and rapid antimicrobial activities against the tested catfish pathogens as compared to cecropin and pleurocidin AMPs and ampicillin, the antibiotic control. When the peptides (2.5 µg of peptide/g of fish) were injected into fish and simultaneously challenged with A. hydrophila through immersion, increased survival rates in Channel Catfish and hybrid catfish were observed in both cathelicidin (alligator and sea snake) treatments as compared to other peptides and the infected control (P < 0.001) with alligator cathelicidin being the overall best treatment. Bacterial numbers in the kidney and liver of Channel Catfish and hybrid catfish also decreased (P < 0.05) for cathelicidin-injected groups at 24 and 48 h after challenge infection. These results show the potential of cathelicidin to protect catfish against bacterial infections and suggest that an approach overexpressing the peptide in transgenic fish, which is the long-term goal of this research program, may provide a method of decreasing bacterial disease problems in catfish as delivering the peptides via individual injection or feeding would not be economically feasible.

White spot syndrome virus (WSSV) is a virulent disease that disrupts shrimp farm operations throughout the world. While the United States has had only limited outbreaks of WSSV within the past several decades, it is important to ensure that this disease does not infect wild penaeid shrimp populations. In Texas, there is a potential for WSSV to spread to wild penaeid populations in the Gulf of Mexico via infected imported nonnative bait shrimp, imported broodstock, or wild crustacean hosts. Due to these potential threats, the Texas Parks and Wildlife Coastal Fisheries Division monitored WSSV in wild brown shrimp Farfantepenaeus aztecus and white shrimp Litopenaeus setiferus from seven major bay systems along the Texas coast during 2019. While no positive samples were detected from the collected shrimp, a power analysis illustrated a potential for low-level WSSV prevalence within Texas shrimp populations that would not be detectable by this monitoring survey. Overall, WSSV does not appear to be a major threat in the Texas region of the Gulf of Mexico, but continual observation and monitoring of wild penaeid shrimp is necessary to protect this resource from future WSSV outbreaks.

Neobenedenia girellae is a pathogenic ectoparasite of many marine fishes, and it causes major epidemics in marine aquaculture. In this study, the efficacy of ethanol extracts of huangqi Astragalus membranaceus (known as milkvetch in North America), guanzhong Dryopteris setosa (known as beaded wood fern in North America), gancao Glycyrrhiza uralensis (known as Chinese licorice in North America), danshen Salvia miltiorrhiza (known as red sage in North America), and pomegranate Punica granatum, as well as seven phytochemicals (10-gingerol, curcumin, cynatratoside-C, emodin, kuwanon-G, kuwanon-O, and sophoraflavanone-G), against adult N. girellae was investigated. In vitro results indicated that pomegranate extract killed all adult N. girellae at a 62.5-mg/L concentration with an 8-h exposure, but gancao extract did not cause 100% mortality until a 1,000-mg/L concentration was used. Additionally, all adult N. girellae died after an 8-h exposure to cynatratoside-C, kuwanon-G, kuwanon-O, or sophoraflavanone-G at a concentration of 125 mg/L. Curcumin, emodin, and 10-gingerol at a concentration of 1,000 mg/L did not kill all parasites after an 8-h exposure. These findings demonstrate that plant extracts and active phytochemicals are potential sources of botanical drugs for controlling N. girellae infection in aquaculture.

Serological assays were conducted for anti-viral hemorrhagic septicemia virus (VHSV) antibodies in four species of fish in Wisconsin (Bluegill Lepomis macrochirus, Brown Trout Salmo trutta, Northern Pike Esox lucius, and Walleye Sander vitreus) to examine spatial and temporal distributions of exposure. Sera were tested for non-neutralizing anti-nucleocapsid antibodies to VHSV by blocking enzyme-linked immunosorbent assay (ELISA). Results (percent inhibition [%I]) were analyzed for differences among species, across geographic distance, and among water management units. Positive fish occurred in 37 of 46 inland water bodies tested, including in water bodies far from reported outbreak events. Using highly conservative species-specific thresholds (mean %I of presumptive uninfected fish + 2 SDs), 4.3% of Bluegill, 13.4% of Brown Trout, 19.3% of Northern Pike, and 18.3% of Walleye tested positive for VHSV antibodies by ELISA. Spatial patterns of seropositivity and changes in %I between sampling years were also analyzed. These analyses explore how serology might be used to understand VHSV distribution and dynamics and ultimately to inform fisheries management.

In March 2017, a wild-caught female common mudpuppy Necturus maculosus from Iowa, USA, with an enlarged posterior abdomen was submitted for diagnostic assessment. The cause of the abdominal distension was a large fluid-filled abdominal mass, diagnosed as a nephroblastoma. Parasites and numerous bacteria were isolated and identified from the mudpuppy but were determined to be incidental. Samples of the neoplasm inoculated onto an American toad Anaxyrus americanus cell line (BufoTad) yielded cytopathic effect during several passages. However, standard molecular testing of the cell culture supernatant failed to identify any viruses. Next-generation sequencing identified the replicating agent as a bacterium of the genus Acholeplasma. Immunohistochemistry confirmed the presence of Acholeplasma within the nephroblastoma, including within tumor cells. This is the first report of nephroblastoma and the second report of neoplasia in this species. The results also suggest that certain bacteria of the genus Acholeplasma might be oncogenic.

Despite the utility of blood analyte evaluation as a diagnostic tool to assist in monitoring the health of marine fishes, baseline data are often lacking for many commercially important finfish species. The objective of this study was to compare hematology and plasma chemistry data for adult wild-caught Almaco Jack Seriola rivoliana at time of capture and again following a period of acclimation to a recirculating aquaculture system and hyposalinity treatment. A total of 30 clinically healthy adult fish were caught via hook and line in the eastern Gulf of Mexico, approximately 120 mi offshore from Madeira Beach, Florida. Blood was collected from a subset of these fish (n = 13) immediately after capture and again at 16 weeks postcapture from another subset (n = 12) following a 45-d antiparasitic hyposalinity treatment. A 19% increase in fish body weight was observed during the study period (16 weeks) and no overt health issues or mortality were noted. Compared to fish that were sampled immediately following capture, several significant differences (P < 0.05) were observed. Absolute white blood cells were lower in captive held fish, suggesting biological variation, antigenic stimulation in wild fish, and/or immunosuppression associated with stress in captive held fish. Lower sodium, chloride, and calculated osmolality indicate osmoregulatory adjustments following the hyposalinity treatment by 16 weeks postcapture. Other observed plasma biochemical differences presumptively reflect dietary and/or environmental changes, or physiological variation following acclimation to captive culture conditions. This study reports baseline blood analyte data of wild-caught Almaco Jack and documents hematological and plasma biochemical responses to their new environment as captive broodstock. Baseline hematological and plasma biochemistry data obtained during this study are the first reported for this species.

Chinook Salmon Oncorhynchus tshawytscha is a keystone fish species in the Pacific Northwest. In 2019, unusual mortalities occurred in two different populations of cultured fingerlings from the same facility in California, USA. The systems consist of outdoor, enclosed, flow-through freshwater tanks that are maintained at 18 ± 1°C. Clinical signs and gross findings were only observed in one population and included abnormal swimming, inappetence, lethargy, skin discoloration, and the presence of multifocal nodular and ulcerative skin lesions. Microscopic lesions were infrequent and consisted of severe, locally extensive granulomatous dermatitis and myositis and mild, multifocal, granulomatous branchitis, myocarditis, and hepatitis. Intracellular acid-fast organisms were observed within areas of granulomatous myositis. Posterior kidney swabs were collected and inoculated in nutrient-rich and selective agar media and incubated at 25°C for 2 weeks. Visibly pure bacterial colonies were observed 7–10 d postinoculation. Partial sequences of 16S rRNA initially identified the recovered bacteria as members of the genus Mycobacterium. However, marked variability was observed among Mycobacterium spp. isolates by using repetitive extragenic palindromic polymerase chain reaction fingerprinting. Amplification and sequencing of the ribosomal RNA internal transcribed spacer, 65-kDa heat shock protein, and RNA polymerase β-subunit gene of the cultured isolates identified M. salmoniphilum and M. chelonae, discrete members of the M. chelonae-abscessus complex, isolated from diseased Chinook Salmon fingerlings.

In recent years, n-butanol, a type of alcohol, has been widely used from the chemical industry to the food industry. In this study, toxic effects of n-butanol's different concentrations (10, 50, 250, 500, 750, 1,000, and 1,250 mg/L) in Zebrafish Danio rerio embryos and larvae were investigated. For this purpose, Zebrafish embryos were exposed to n-butanol in acute semistatic applications. Teratogenic effects such as cardiac edema, scoliosis, lordosis, head development abnormality, yolk sac edema, and tail abnormality were determined at different time intervals (24, 48, 72, 96, and 120 h). Additionally, histopathological abnormalities such as vacuole formation in brain tissue and necrosis in liver tissue were observed at high doses (500, 750, and 1,000 mg/L) in all treatment groups at 96 h. It was determined that heart rate decreased at 48, 72, and 96 h due to an increase in concentration. In addition, alcohol-induced eye size reduction (microphthalmia) and single eye formation (cyclopia) are also among the effects observed in our research findings. In conclusion, n-butanol has been observed to cause intense neurotoxic, teratogenic, and cardiotoxic effects in Zebrafish embryos and larvae.

Reports of intussusception in sea turtles are generally linked to marine debris ingestion; therefore, only a few cases of the disease are associated with parasitic infestations. The objective of this study was to describe the necropsy findings of the first reported case of colocolic intussusception in a green sea turtle Chelonia mydas, associated with the helminth Octangium sp. A juvenile female green sea turtle, which was registered and rescued by the team from the Cetaceans Project of Costa Branca, State University of Rio Grande do Norte, was examined. The animal died 1 d after being treated and was immediately submitted for necropsy. Our findings indicated that parasitic infestation by Octangium sp. in the green sea turtle caused intussusception and consequently led to the animal’s death. Early diagnosis and surgical correction are fundamental for a good prognosis and, consequently, for successful rehabilitation of marine species.