Case report: Blindness associated with Learedius learedi trematode infection in a green sea turtle, Chelonia mydas, of the northern Red Sea

Spirorchiid blood flukes are widespread in sea turtles, causing disease and mortality in their populations, with high prevalence in several ocean basins. Besides being leading parasitic causes of sea turtle strandings in several parts of the world, these infectious agents can cause endocarditis, vasculitis, thrombosis, miliary egg granulomas, and aneurysms, which ultimately may compromise the survival of green sea turtles. More severe cases may also result in multifocal granulomatous meningitis or pneumonia, both of which can be fatal. Herein, we report the first case of severe trematode infection, Caused by Learedius learedi, in a green sea turtle in the northern Red Sea; this infection is associated with bilateral blindness. Necropsy revealed multiple granulomas with intralesional trematode eggs in the optic nerve, eyes, spleen, heart, and lungs. The parasite was identified as Learedius learedi through specific primers of the ribosomal genome and COI sequences obtained from GenBank. Altogether, these findings emphasize the importance of recognizing the systemic nature of this particular fluke infection to ultimately protect the lives of these marine animals and ensure the sustainability of these species in the wild

Morphological description and molecular characterization of Contracaecum larvae (Nematoda: Anisakidae) parasitizing market-size hybrid tilapia (Oreochromis aureus x Oreochromis niloticus) and red drum (Sciaenops ocellatus) farmed in Israel

Nematodes belonging to the genus Contracaecum (family: Anisakidae) are heteroxenous parasites with a complex life cycle. Contracaecum larvae infecting farmed fish and fishery products are economically important causing market rejection in massive infection and may have zoonotic potential. In Israel, Contracaecum larvae have been described morphologically in several fish species; however, none of these descriptions were supported by molecular tools. In 2019–2020, hybrid tilapia (Oreochromis aureus x Oreochromis niloticus) and red drum (Sciaenops ocellatus), farmed in polyculture were found to be heavily infected with nematodes referable to Contracaecum larvae. Prevalence of infection in hybrid tilapia and red drum was 53.8% and 40.9%, respectively. A combined (morphological and molecular) approach revealed that both infected fish species were parasitized by the same species of Contracaecum, although larvae in hybrid tilapia were localized in the pericardial cavity whereas in red drum, they were observed in the abdominal cavity. Genetic analysis of internal transcribed spacer rDNA and cox2 mtDNA showed high similarity to unidentified Contracaecum larvae detected in several fish species in Ethiopia, Egypt and Kenya. In this study, molecular and morphological analyses place the possible new species in the C. multipapillatum complex and was provisionally named C. multipapillatum E. Further analyses combining morphological and molecular approaches are required on adult specimens collected from piscivorous birds living in the same area to support the identification of a potentially new species

Fatal Infection in a Wild Sandbar Shark (Carcharhinus plumbeus), Caused by Streptococcus agalactiae, Type Ia-ST7

Streptococcus agalactiae is one of the most important fish pathogenic bacteria as it is responsible for epizootic mortalities in both wild and farmed species. S. agalactiae is also known as a zoonotic agent. In July 2018, a stranded wild sandbar shark (Carcharhinus plumbeus), one of the most common shark species in the Mediterranean Sea, was found moribund on the seashore next to Netanya, Israel, and died a few hours later. A post-mortem examination, histopathology, classical bacteriology and advanced molecular techniques revealed a bacterial infection caused by S. agalactiae, type Ia-ST7. Available sequences publicly accessible databases and phylogenetic analysis suggest that the S. agalactiae isolated in this case is closely related to fish and human isolates. To the best of our knowledge, this is the first description of a fatal streptococcosis in sandbar sharks

Mycobacteriosis in Aquatic Invertebrates: A Review of Its Emergence

Mycobacteriosis is a chronic bacterial disease reported in aquatic and terrestrial animals, including humans. The disease affects a wide range of cultured and wild organisms worldwide. Mycobacteriosis is well-known in aquatic vertebrates (e.g., finfish, marine mammals), while in the last few years, reports of its presence in aquatic invertebrates have been on the rise, for both freshwater and marine species. The number of cases is likely to increase as a result of increased awareness, surveillance and availability of diagnostic methods. Domestication of wild aquatic species and the intensification of modern aquaculture are also leading to an increase in the number of reported cases. Moreover, climate changes are affecting fresh and marine aquatic ecosystems. The increasing reports of mycobacteriosis in aquatic invertebrates may also be influenced by global climate warming, which could contribute to the microbes’ development and survival rates, pathogen transmission and host susceptibility. Several species of the genus Mycobacterium have been diagnosed in aquatic invertebrates; a few of them are significant due to their wide host spectrum, economic impact in aquaculture, and zoonotic potential. The impact of mycobacteriosis in aquatic invertebrates is probably underestimated, and there is currently no effective treatment other than facility disinfection. In this review, we provide an overview of the diversity of mycobacterial infections reported in molluscs, crustaceans, cnidarians, echinoderms and sponges. We highlight important issues relating to its pathological manifestation, diagnosis and zoonotic considerations.</jats:p

Mycobacteriosis in Aquatic Invertebrates: A Review of Its Emergence

Mycobacteriosis is a chronic bacterial disease reported in aquatic and terrestrial animals, including humans. The disease affects a wide range of cultured and wild organisms worldwide. Mycobacteriosis is well-known in aquatic vertebrates (e.g., finfish, marine mammals), while in the last few years, reports of its presence in aquatic invertebrates have been on the rise, for both freshwater and marine species. The number of cases is likely to increase as a result of increased awareness, surveillance and availability of diagnostic methods. Domestication of wild aquatic species and the intensification of modern aquaculture are also leading to an increase in the number of reported cases. Moreover, climate changes are affecting fresh and marine aquatic ecosystems. The increasing reports of mycobacteriosis in aquatic invertebrates may also be influenced by global climate warming, which could contribute to the microbes&rsquo; development and survival rates, pathogen transmission and host susceptibility. Several species of the genus Mycobacterium have been diagnosed in aquatic invertebrates; a few of them are significant due to their wide host spectrum, economic impact in aquaculture, and zoonotic potential. The impact of mycobacteriosis in aquatic invertebrates is probably underestimated, and there is currently no effective treatment other than facility disinfection. In this review, we provide an overview of the diversity of mycobacterial infections reported in molluscs, crustaceans, cnidarians, echinoderms and sponges. We highlight important issues relating to its pathological manifestation, diagnosis and zoonotic considerations