Sporotrichosis is caused by the fungus Sporothrix schenckii, which is found in vegetation. Infection commonly occurs when the skin is broken while handling plant materials such as rosebushes, briars, or mulch-rich dirt.

Sporotrichosis can be an occupational disease (for farmers, horticulturists, rose gardeners, plant nursery workers). Widespread (disseminated) sporotrichosis can develop in immunocompromised people when they inhale spore-laden dust.

Symptoms include a small, painless, red lump that develops at the site of infection and ultimately develops into an ulcer. Lesions are often on the hands and forearm, as these areas are a common site of injury.

The organism follows the lymph flow causing small ulcers to appear in lines on the skin as the infection progresses up the arm (or leg). These lesions do not heal unless treated and may remain ulcerated for years.

Systemic sporotrichosis can cause lung and breathing problems, osteomyelitis, arthritis, and meningitis.