Cutaneous Granulomas in Dolphins Caused by Novel Uncultivated Paracoccidioides brasiliensis.

Raquel Vilela,John S. Reif,Patricia A. Fair,Gregory D. Bossart,Leslie M. Dalton,Leonel Mendoza,Judy A. St. Leger,Peter J. McCarthy,Adam M. Schaefer

doi:10.3201/eid2212.160860

Abstract

Cutaneous granulomas in dolphins were believed to be caused by Lacazia loboi, which also causes a similar disease in humans. This hypothesis was recently challenged by reports that fungal DNA sequences from dolphins grouped this pathogen with Paracoccidioides brasiliensis. We conducted phylogenetic analysis of fungi from 6 bottlenose dolphins (Tursiops truncatus) with cutaneous granulomas and chains of yeast cells in infected tissues. Kex gene sequences of P. brasiliensis from dolphins showed 100% homology with sequences from cultivated P. brasiliensis, 73% with those of L. loboi, and 93% with those of P. lutzii. Parsimony analysis placed DNA sequences from dolphins within a cluster with human P. brasiliensis strains. This cluster was the sister taxon to P. lutzii and L. loboi. Our molecular data support previous findings and suggest that a novel uncultivated strain of P. brasiliensis restricted to cutaneous lesions in dolphins is probably the cause of lacaziosis/lobomycosis, herein referred to as paracoccidioidomycosis ceti.

Highlights

Cutaneous granulomas in dolphins were believed to be caused by Lacazia loboi, which causes a similar disease in humans
PCR Amplification and Analysis by Using Basic Local Alignment Search Tool Microscopically, the 6 silver-stained specimens showed branching chains of yeast-like cells connected by small isthmuses, which is typical of this pathogen from infected dolphins with lacaziosis/lobomycosis (Figure 1)
Alignment of P. brasiliensis and L. loboi sequences from humans available in GenBank showed that partial Kex gene sequences of these fungi from dolphins were similar to those of P. brasilienis from humans

Summary

Introduction

Cutaneous granulomas in dolphins were believed to be caused by Lacazia loboi, which causes a similar disease in humans. The notion that human L. loboi was the same organism as those in the skin of dolphins with lacaziosis/lobomycosis was first challenged by Rotstein et al (13), who used molecular analysis These investigators found that the 28S rDNA amplicon of L. loboi in extracted genomic DNA from an infected bottlenose dolphin (Tursiops truncatus) in North Carolina, USA, coastal areas had 97% identity with P. brasiliensis DNA sequences available in GenBank. 3 groups in Japan (14,15) and Spain (16), who used molecular methods, reported similar observations for several dolphin species including, T. truncatus and Lagenorhynchus obliquidens, which had skin granulomas and yeast-like cells in infected tissues These studies showed that glycoprotein 43 (gp43)–like and ITS partial DNA sequences isolated from infected dolphins placed the etiologic agent of skin granulomas among human P. brasiliensis strains.

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Conclusion