Sporotrichosis is a subacute or chronic fungal infection caused by Sporothrix schenckii and related species. It occurs most commonly in cutaneous or lymphocutaneous forms resulting from direct inoculation of the pathogen but also occurs in a variety of extracutaneous forms. Among the extracutaneous forms, a primary sporotrichotic pneumonia, presumably acquired by inhalation, occurs rarely. More commonly, musculoskeletal or osteoarticular sporotrichosis occurs, either as a result of direct inoculation into tendons, bursae, and joints or as a result of hematogenous dissemination. Hematogenous dissemination may result in disseminated cutaneous sporotrichosis and/or infection of a variety of unusual sites, including the meninges.

Epidemiology

Sporothrix schenckii is widely distributed in nature; it grows on plant debris in soil, and on the bark of trees, shrubs, and garden plants. The fungus and the disease occur in much of the world, primarily in the tropical and temperate zones. The abundance of the organism and the reported incidence of the disease show great geographic variation, perhaps related to genotypic differences between organisms in different locales. The penetrating trauma that introduces the fungal conidia into the human host is most commonly accomplished by splinters, thorns, or woody fragments of plants, but any contact with plants or plant products (e.g., sphagnum peat moss, mulch, hay, timber) accompanying minor skin trauma may initiate infection. Activities most frequently associated with acquisition of sporotrichosis include gardening (particularly rose gardening), landscaping, farming, berry-picking, horticulture, and carpentry. Skin test and serologic surveys demonstrate that most S. schenckii inoculations promote the development of immunity without clinically apparent infection. Zoonotic transmission also occurs from infected animals, particularly cats with extensive skin lesions, but may result from the scratch of any digging animal. Both pulmonary and disseminated sporotrichosis appear to occur more commonly in patients with a history of alcoholism.