RHINOSPORIDIOSIS - A DESCRIPTION OF AN UNPRECEDENTED OUTBREAK IN CAPTIVE SWANS (CYGNUS SPP) AND A PROPOSAL FOR REVISION OF THE ONTOGENIC NOMENCLATURE OF RHINOSPORIDIUM-SEEBERI

Rhinosporidiosis is a mucocutaneous zooanthroponotic disease caused by Rhinosporidium seeberi, a fungal-like organism of uncertain classific ation with an unknown mode of transmission. Over a 3 year period, 41 c aptive swans (Cygnus olor and C. atratus) developed conjunctival and c utaneous polypoid lesions diagnosed as rhinosporidiosis by histopathol ogical examination including light and electron microscopy. Investigat ion of this avian outbreak, the first of its kind, provides additional insight into the epidemiology of this enigmatic aetiologic agent, whi ch has yet to be isolated and cultivated in vitro. The occurrence of r hinosporidiosis in swans supports an aquatic environment as the reserv oir for R seeberi, which is often associated with exposure to water. W e report the first known occurrence of rhinosporidiosis in 41 captive mute (C. olor) and Australian black (C. atratus) swans dwelling on a l ake in a Central Florida city. Additionally, we review the development stages of R. seeberi and propose a revision in its ontogenic nomencla ture to reflect its probable taxonomic classification as a member of t he kingdom Fungi.