DAO 101:23-31 (2012)  -  DOI: https://doi.org/10.3354/dao02506

Dermatitis and systemic mycosis in lined seahorses Hippocampus erectus associated with a marine-adapted Fusarium solani species complex pathogen

Caroline E. Salter1, Kerry O’Donnell2, Deanna A. Sutton3, David P. Marancik1, Susan Knowles1, Tonya M. Clauss4, Aimee L. Berliner4, Alvin C. Camus1,*

1Department of Pathology, The University of Georgia College of Veterinary Medicine, Athens, Georgia 30602, USA
2Bacterial Foodborne Pathogens and Mycology Research Unit, National Center for Agricultural Utilization Research, US Department of Agriculture, Agricultural Research Service, Peoria, Illinois 61604, USA
3Department of Pathology, University of Texas Health Science Center, San Antonio, Texas 78229, USA
4Department of Veterinary Services, Georgia Aquarium, Inc., Atlanta, Georgia 30313, USA
*Corresponding author. Email:

ABSTRACT: During a 4 mo epizootic, 100% of 152 lined seahorses Hippocampus erectus in 3 separate groups died while in quarantine following shipment to a public aquarium. Twelve animals with skin depigmentation and ulceration were received by the Aquatic Pathology Service, College of Veterinary Medicine, University of Georgia, Athens, Georgia, USA, for diagnostic evaluation. Microscopically, lesions in 11 seahorses included multifocal epithelial necrosis and ulceration associated with 2 to 7 µm diameter, branching, septate fungal hyphae, typically accompanied by deeper infiltration into underlying skeletal muscle. Angioinvasion, with vascular thrombosis and tissue infarction, was a prominent feature in multiple animals. Fungal invasion of one or more internal organs was observed in 4 animals. Hyphae appeared to course freely through tissues and elicited little or no inflammatory response. Fusariosis has been reported sporadically in fish and other aquatic organisms, but identification has often been limited to the genus level based solely on morphologic features. Morphologic characteristics of the fungus isolated from this case were consistent with the Fusarium solani species complex (FSSC), which includes over 50 members that can only be identified definitively using DNA sequence data. A 3-locus typing scheme identified the isolate as a distinct species/haplotype, designated FSSC 12-a, belonging to a specific lineage that appears adapted to aquatic environments and disease in marine animals. Empirical treatment with itraconazole failed to stop mortalities, and subsequent in vitro antifungal susceptibility data explained a lack of clinical efficacy for this agent. Effective treatment in human medicine has similarly been limited by poor susceptibility to several classes of antifungal compounds.


KEY WORDS: Seahorse · Fusarium · Mycosis · Histopathology · DNA typing · Phylogenetic analysis


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Cite this article as: Salter CE, O’Donnell K, Sutton DA, Marancik DP and others (2012) Dermatitis and systemic mycosis in lined seahorses Hippocampus erectus associated with a marine-adapted Fusarium solani species complex pathogen. Dis Aquat Org 101:23-31. https://doi.org/10.3354/dao02506

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