Sporotrichosis is a sporadic, subacute, or chronic, granulomatous, mycotic infection of dogs caused by the saprophytic theriomorphic fungus Sporothrix Schenckii. This has a worldwide distribution with focal areas of hyperendemicity. This saprophyte is prevalently distributed more in tropical/subtropical areas and temperate zones soil, rose bushes, decaying wood, sphagnum moss, hay, and contaminated timbers.
Also known as the “gardener’s mycosis” or “rosebush mycosis”, this was first reported by the Johns Hopkins Hospital medical student Benjamin Schenck in 1898, in Baltimore, USA. In 1900, Perkins and Hektoen described another case in Chicago and proposed the name-‘ Sporothrix Schenckii’ due to the reproduction characteristics. Several microbiological studies have established that S. Schenckii is a group of no less than six clinico-epidemiologically significant species with noteworthy differences in different disease patterns, degree of virulence, biochemical properties (sucrose, dextrose, raffinose assimilation, etc), response to therapy and geographical distribution. These include S. Globosa (in Italy, UK, Spain, USA, India, China, and Japan), S. Mexicana (in Mexico), S. Brasiliensis (in Brazil), and S. Schenckii Sensu strict, and S. Albicans. Hence, it is collectively called “Sporothrix Schenckii species complex” rather than the earlier nomenclature “Sporothrix Schenckii”.
In simple infections, lesions are usually restricted to the infection site, such as the respiratory tract (following inhalation) or the skin (following skin trauma). In more complicated cases, disseminated sporotrichosis may happen in which multiple organs (e.g., lungs, joints, skin) may be affected; immunocompromised dogs may be predisposed to this fungal infection.
The disease affects mostly rural dogs and persons related to plants or plant material professions such as gardeners, farmers, florists, nursery workers, and foresters. S. Schenckii inoculation is accessed into the skin by traumatic insertion from contaminated soil, hay stalks, thorns, barbs, and splinters causing cutaneous infection. There are reports of zoonotic transmission documented from fish consumption, insect bites, and bites of other dogs, cats /other infected animals.