Abstract
Mesomycetozoea are parasites that show characteristics of protists and fungi.1 They were previously classified as Ichthyosporea and include Dermocystidium, Ichthyophonus, Psorospermium, and Sphaerothecum spp.1 Infections in fish and amphibians often cause granulomatous lesions in the skin, muscle, or gills, while other infections may be systemic.2 Pathogenicity varies and high mortalities have been reported in fish.1,2
Mesomycetozoea were identified in cardinal tetras (Paracheirodon axelrodi) and green neon tetras (Paracheirodon simulans) from five different populations. The predominant clinical signs were macroscopic, white, vermiform structures in the skin and within the periocular space. Coelomic distension and periocular edema were seen in some individuals. Morbidity varied from 10–100%. No mortalities could be directly attributed to the infection. The parasites were readily visible on skin scrape and histopathology. Histopathologic lesions of euthanized individuals also included dermatitis, myositis, and periocular cellulitis. For further identification, tissues from three of the affected populations were submitted for PCR analysis and sequencing of the small subunit rRNA. Further analysis is pending, but the parasites were closely related to Dermocystidium salmonis.
* Presenting author
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Literature Cited
1. Glockling SL, Marshall WL, Gleason FH. Phylogenetic interpretations and ecological potentials of the Mesomycetozoea (Ichthyosporea). Fungal Ecol. 2013;6(4):237–247.
2. Rowley J, Gleason F, Andreou D, Marshall W, Lilje O, Gozlan R. Impacts of mesomycetozoean parasites on amphibian and freshwater fish populations. Fungal Biol Rev. 2013;27(3–4):100–111.