chapter 44 Sporotrichosis........................................
DEFINITION/OVERVIEW
Zoonotic fungal disease affecting the skin and lymphatics; may become systemic.
ETIOLOGY/PATHOPHYSIOLOGY
Sporothrixspp. are saprophytes in soil, decomposing plants, peat moss, rose thorns,
and wood.
Disease caused by direct inoculation into subcutaneous tissues of the thermally
dimorphic fungus with conversion from mycelial form to yeast form in mammalian
tissues.Described on all continents: most prevalent serotype differs by geographic location.
S. schenckiiis a cryptic species with a high level of intraspecific DNA variability, lead-
ing to two or more species having been originally classified as a single species.
Pathogenic serotypes within theSporothrixcomplex includeS.brasiliensis,S.schenckii
sensu stricto,S. globosa,S. mexicana,andS. luriei.
Lesions in cats typically contain high fungal loads: yeast forms scarce in human and
canine lesions.
Cats may be subclinical carriers as well as being the main zoonotic disseminators of
Sporothrixinfection.
Cellular immunity is involved in disease resolution – severe systemic disease and high
fungal load are associated with increased expression of CD8+cells; localized, orga-
nized control of disease and low fungal load are associated with increased expression
of CD4+cells (cats); recent studies correlate CD8+release and subsequent activation
(by inflammasomes/caspase-1) of IL-1-beta with severity of lesions.Disease manifestation is dependent on species virulence; independent of coinfection
with feline retroviruses.
SIGNALMENT/HISTORY
Causes and Risk Factors
Dogs: hunting dogs from puncture wounds associated with thorns or splinters.
Blackwell’s Five-Minute Veterinary Consult Clinical Companion: Small Animal Dermatology, Third Edition.
Karen Helton Rhodes and Alexander H. Werner.
©2018 John Wiley & Sons, Inc. Published 2018 by John Wiley & Sons, Inc.
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