Diseases of aquatic organisms最新文献

Green turtles Chelonia mydas are vital components of marine ecosystems and are recognized as indicators of environmental health. Fibropapillomatosis (FP), a debilitating disease associated with a chelonid herpesvirus, disproportionately affects juveniles in coastal foraging areas. This study presents the first analysis of FP dynamics in Babitonga Bay, southern Brazil, an important habitat for the species. Between 2019 and 2023, 171 juvenile green turtles were monitored using capture-mark-recapture and photo-identification techniques. FP prevalence in Babitonga Bay was among the highest reported in Brazil, reaching 53.2%. Tumors were predominantly located in the anterior region of the body, particularly around the flippers and axillary area, and were mostly small, consistent with mild FP. Disease severity was quantified using an FP index, and its association with body condition was examined, revealing no significant association. Data from recaptured individuals revealed both tumor progression and regression, underscoring individual variability and suggesting the influence of environmental and immunological factors. The predominance of FP in juveniles highlights their heightened vulnerability during early developmental stages. These findings enhance our understanding of FP dynamics in green turtles and support the need for continued health assessments and conservation measures. This research contributes to global efforts to safeguard marine biodiversity, aligning with the goals of the United Nations Decade of Ocean Science for Sustainable Development.

We report significant pathological findings from 272 stranding investigations of 20 cetacean species in the Pacific Islands region between 2006 and 2024. Full or partial necropsies of 209 cases (76.8%) resulted in one or more diagnoses associated with death in 137 cases. Natural disease accounted for 62% of stranded animals; approximately half were in poor body condition due to chronic illness. Morbillivirus and Brucella sp. infections caused mortality in 11 species, including striped dolphins and Longman's beaked whales. Toxoplasmosis, of anthropogenic cause in Hawai'i, led to deaths of 2 spinner dolphins and a bottlenose dolphin. Pygmy and dwarf sperm whales, beaked whales and pilot whales showed heavy parasitism by nematodes, cestodes and trematodes. Approximately 12.4% of stranded individuals were perinates/neonates, with 3 cases of dystocia with maternal mortality. Anthropogenic trauma was observed in 29.2% of strandings, including 6 goose-beaked whales with cranial and/or microvascular hemorrhages. Vertebral and skull fractures were attributed to direct vessel strikes for 2 pygmy sperm whales, 2 humpback whale calves, a goose-beaked whale, a spinner dolphin and a striped dolphin. Blast trauma was observed in 3 Fraser's dolphins in an uncommon stranding event. Significant plastic debris and/or fishery debris were found in stomachs of 6 species, with fatal gastric obstruction in a sperm whale and fatal fishhook penetration in a bottlenose dolphin. This study highlights the value of necropsy examinations in a region inhabited by small island-associated populations where carcass recovery rates are low, and cetaceans face an array of natural and anthropogenic threats.

Access to clean water is a fundamental Sustainable Development Goal that is increasingly undermined by emerging microbial contaminants linked to urbanization, pollution, overfishing, and climate change. This paper investigates the rising incidence of mycobacterial infections in aquatic environments, from potable and surface waters to marine and aquaculture systems, with a particular focus on the Mediterranean Sea. The region, a biodiversity hotspot, exemplifies how climate-induced thermal shifts, combined with anthropogenic pressures, enhance pathogen survival and disease transmission in fish, especially in species with limited thermoregulation. The study synthesizes evidence on the global distribution of various Mycobacterium species, their modes of transmission, and their clinical impacts on a wide range of aquatic organisms. It further explores the challenges posed by ineffective water disinfection, biofilm-associated persistence, and regulatory gaps that complicate disease management. The findings underline the critical need for integrated public health strategies and sustainable aquaculture practices to mitigate the dual threats to marine biodiversity and human health posed by these emerging infections.

Mycobacteria infections are sporadically documented in wild sea turtles and are generally regarded as opportunistic pathogens. This case series describes infections by a Mycobacterium ulcerans ecovar in 2 imperiled species of sea turtle, the Kemp's ridley Lepidochelys kempii (n = 5) and loggerhead turtle Caretta caretta (n = 1). Most cases were stranded animals that presented with neurological abnormalities resulting from severe mycobacterial meningoencephalitis. In 4 instances, infected turtles were found in relative proximity to one another and without evident predisposing conditions, suggesting the potential for broader population health significance. Lesions were predominantly heterophilic and histiocytic, and were characterized by extensive leukocytic necrosis, absence of organized granuloma formation within the nervous system, fibrinoid vascular necrosis, and myriad extracellular and intrahistiocytic acid-fast bacilli. Except for one severely bacteremic animal, involvement of visceral organs was relatively mild and often paucibacterial. Multiple genetic loci were 100% identical in all 6 affected turtles and to multiple reported M. ulcerans ecovars; an ITS2 sequence amplified from each turtle was 100% identical only to M. pseudoshottsii, a pathogen of wild and farmed fish. The genetic relatedness of the organism to M. ulcerans ecovars known to produce mycolactones (polyketide toxins) suggests that the distinct pathological features among these cases are the result of a mycolactone-producing species of mycobacteria. This is the first report of M. ulcerans ecovar infection of a reptile. Mycobacterial meningoencephalitis should be considered as a differential etiological diagnosis for neurological disease in wild sea turtles.

Two supersaturation events caused gas bubble disease (GBD) in captive Melibe leonina (lion's mane sea slugs). For the first event (a), supersaturation spikes (114-127% total dissolved gas [TDG]) occurred on Days 1a, 4a, and 23a. On Day 5a, nearly all 77 animals developed grossly visible gas bubbles within vasculature. Two recompression treatments were performed on 2 cohorts: (1) 7 animals were placed at 8.5 m depth (103 kPa) and unmonitored for 5 d, after which they had resolution of gas bubbles; and (2) 12 animals were placed in a hyperbaric chamber (152 kPa) for 5 d and had resolution of gas bubbles within 2 h of treatment initiation. Untreated animals had slow, consistent improvement with complete resolution at Day 12a. Starting on Day 23a (date of a supersaturation spike) through Day 79a, 0-4 animals died per day, totaling 60 deaths (78% mortality), after which no further mortalities occurred. After the first supersaturation event, 17 animals remained, and 16 new animals were added to the tank. Two months later, during the second event (b), supersaturation spikes (106-110% TDG) occurred on Days 1b, 2b, and 6b-15b. On Day 15b, all M. leonina developed grossly visible bubbles and were placed in a hyperbaric chamber for 14 d; gas bubbles resolved, and no mortalities occurred in the second event. Histologically, gas emboli were in the hemolymphatic sinuses and caused soft tissue edema. The cause for GBD was unknown for the first event and, for the second event, was due to cracked plumbing valves.

This work was performed to generate the data needed to set epidemiological cut-off values for inhibition zone data of 8 antimicrobial agents against Vibrio parahaemolyticus determined using standardised disc diffusion protocols with incubation at 35 ± 2°C for 16 to 20 h and at 28 ± 2°C for 24 to 28 h. The zone diameter data aggregated from 3 to 5 laboratories were analysed by the normalised resistance interpretation algorithm. Cut-off values calculated from data obtained at 35 and 28°C were ≥23 and ≥24 mm for ceftazidime, ≥18 and ≥20 mm for enrofloxacin, ≥28 and ≥29 mm for florfenicol, ≥14 and ≥14 mm for gentamicin, ≥29 and ≥32 mm for meropenem, ≥17 and ≥18 mm for oxolinic acid, ≥22 and ≥24 mm for oxytetracycline, as well as ≥19 and ≥21 mm for trimethoprim/sulfamethoxazole. The influence of the incubation temperature on inhibition zone sizes was investigated by calculating the difference between the zones obtained at 35 and 28°C for a specific antimicrobial agent with a particular isolate by an individual laboratory. The mean of the differences calculated for 1314 paired observations was 0.38 mm with a standard deviation of 2.68 mm. The data generated in this work will be submitted to the Clinical and Laboratory Standards Institute and the European Committee on Antimicrobial Susceptibility Testing for consideration in their setting of internationally agreed-upon epidemiological cut-off values for V. parahaemolyticus that are essential for interpreting antimicrobial susceptibility testing data of this species.

Edwardsiella ictaluri is a pathogenic bacterium that poses a significant threat to the economic viability of aquaculture. However, the effects of E. ictaluri infection on the non-specific immune response of hybrid grouper and the regulatory mechanisms of oligochitosan in modulating the infection are poorly understood. We investigated the impact of oligochitosan supplementation on the growth performance, biochemical parameters, immune response, and apoptosis in hybrid grouper infected with E. ictaluri. The results showed that oligochitosan significantly improved the weight and length of hybrid grouper, whereas E. ictaluri infection reduced their growth performance. Histopathological analysis of the head kidney showed no significant differences among the groups. Biochemical analysis revealed that E. ictaluri significantly increased the activity of serum glutamate-oxaloacetate transaminase (GOT) and glutamate-pyruvate transaminase (GPT), while decreasing the activities of catalase (CAT) and superoxide dismutase (SOD), with oligochitosan ameliorating these effects. E. ictaluri infection also significantly elevated the GOT activity in the head kidney while reducing CAT and SOD activities. The analysis of inflammatory factor expression revealed that E. ictaluri significantly increased the levels of IL-8, TNF-α, and IKKα, whereas oligochitosan effectively decreased these inflammatory markers. Apoptosis gene expression analysis indicated that E. ictaluri infection significantly upregulated bax, caspase-3, and caspase-8, while supplementation with oligochitosan reduced their expression levels. TdT-mediated dUTP nick-end labeling signals were significantly increased following E. ictaluri infection, while supplementation with oligochitosan notably reduced them. In conclusion, oligochitosan can regulate growth, immune response, and apoptosis, potentially protecting hybrid grouper infected with E. ictaluri.

This study analysed published data on the distributions of minimum inhibitory concentrations of a group of freshwater isolates classified as Aeromonas spp. with the aim of establishing whether they provided any evidence that epidemiological cut-off values set from these data would be unreliable. This group contained 233 isolates and included members of at least 11 species. The standard deviations (SDs) of the wild-type distributions for 10 antimicrobial agents were calculated for this multi-species group using the ECOFFinder and normalised resistance interpretation (NRI) algorithms. These were compared to the SDs of 110 distributions established for individual species published by the European Committee on Antimicrobial Susceptibility Testing. Fifty-one of these distributions had been generated by multiple laboratories and 59 by single laboratories. When the ECOFFinder algorithm was used to calculate the SDs, the mean for the multi-species group was 0.63 log2 µg ml-1, and the 51 individual species and multiple-laboratory groups were 0.68 and 0.65 log2 µg ml-1, respectively. When the NRI algorithm was used, the mean for the multi-species group was 0.79 log2 µg ml-1, and the 51 individual species and multiple-laboratory groups were 0.79 and 0.76 log2 µg ml-1, respectively. These comparisons indicate that the heterogeneity in the susceptibility to antimicrobial agents within the multi-species group of Aeromonas is not significantly different from that recorded for individual species. This analysis, therefore, suggests that epidemiological cut-off values designed to be applied to all members of the genus Aeromonas would not be inherently unreliable.

This report describes a severely emaciated adult female bottlenose dolphin Tursiops truncatus found dead in September 2021 with numerous traumatic injuries. The animal stranded in coastal Alabama, USA, a hotspot in the Gulf of Mexico for trauma-related marine mammal strandings. A combination of traditional and advanced diagnostic techniques including postmortem examination, histopathology, and computed tomography revealed trauma from multiple events, including rib and vertebral fractures of varying chronicity and a more recent catfish barb penetrating the diaphragm with associated tissue necrosis. Tooth growth layer group analysis indicated this individual was ~40 yr old, despite a total straight length notably less than is typically reported for an adult female T. truncatus in the region. Advanced age was also supported by tooth wear, evidence of multiple pregnancies, fusion of sternal bones, and age-related changes in the heart and liver. This case illustrates a multifactorial cause of death in a coastal bottlenose dolphin and highlights the value of combining traditional postmortem examination with advanced imaging techniques to more accurately determine cause of death in the presence of multiple traumatic injuries.

Shellfish fisheries and aquaculture within the Chesapeake Bay (hereafter 'the Bay') and its tributaries have been historically impacted by disease and climate events. Climate-driven shifts in temperature and salinity can alter host-parasite dynamics, influencing outbreaks. Here, we explore the relationship between temperature, salinity and parasite distribution and abundance in the eastern oyster Crassostrea virginica-Perkinsus marinus system. We use long-term (30 yr) environmental data and P. marinus surveys in the Bay to identify (1) how climate affects P. marinus prevalence and intensity, (2) seasonal and climate-driven infection patterns, and (3) regional environmental influences on disease. We found significant relationships between P. marinus infection intensity, prevalence, increasing temperature and decreasing salinity. Our results indicated that there is an overall decreased abundance of P. marinus prevalence and intensity throughout the Bay driven by decreases in salinity over time, most prominently from 2003-2020. However, these temporal trends in prevalence and intensity vary largely by region, with some regions still experiencing high disease burden. Examining monthly environmental parameters reinforced the dominant role of salinity in driving disease patterns. Salinity had significant relationships with prevalence and intensity year-round, with the largest effects in late spring/early summer. Monthly temperatures had fewer significant relationships to prevalence and intensity, but the largest significant effects were seen in late winter/early spring. Notably, this study is the first to document that winter salinity influences fall parasite prevalence, sometimes exerting a greater effect than temperature. Continued and expanded monitoring of marine disease is crucial to understand how the changing climate is impacting disease.