Sporotrichosis is an infection of the skin caused by a fungus, Sporothrix schenckii. This fungus is related more closely to the mold on stale bread or the yeast used to brew beer than to bacteria that usually cause infections. The mold is found on rose thorns, hay, sphagnum moss, twigs, and soil. The infection is more common among gardeners, nursery workers, and farmers who work with roses, moss, hay, and soil.
Once the mold spores move into the skin, the disease takes days or even months to develop.
Causes of Sporotrichosis
Sporotrichosis usually begins when mold spores are forced under the skin by a rose thorn or sharp stick, although the infection can begin in apparently unbroken skin after contact with hay or moss carrying the mold.
More rarely, cats or armadillos can transmit the disease.
In rare cases, the fungus can be inhaled or ingested, causing infection in parts of the body other than the skin.
Sporotrichosis does not appear to be transmitted from person to person.
Symptoms of Sporotrichosis
The first symptom of sporotrichosis is a firm bump (nodule) on the skin that can range in color from pink to nearly purple. The nodule is usually painless or only mildly tender. Over time, the nodule may develop an open sore (ulcer) that may drain clear fluid. Untreated, the nodule and the ulcer become chronic and may remain unchanged for years.
In about 60% of cases, the mold spreads along the lymph nodes. Over time, new nodules and ulcers spread in a line up the infected arm or leg. These can also last for years.
In very rare cases, the infection can spread to other parts of the body, such as the bones, joints, lungs, and brain. This is more common among those with a weakened immune system. It can be difficult to treat and may be life threatening.