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Sporotrichosis

Sporotrichosis Overview

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. Therefore, the infection is more common among gardeners who work with roses, moss, hay, and soil.

Causes of Sporotrichosis

Some of the causes of sporotrichosis include:

  • Sporotrichosis usually begins when mold spores are forced under the skin by a rose thorn or sharp stick.
  • The infection can also begin in apparently unbroken skin after contact with hay or moss carrying the mold.
  • Farmers, nursery workers, landscapers, and gardeners are at higher risk for the disease.
  • More rarely, cats or armadillos can transmit the disease.
  • In very rare cases, the organism can be inhaled or ingested, leading to infection of parts of the body other than the skin.
  • The disease does not appear to be transmitted from person to person.

Symptoms of Sporotrichosis

Some symptoms of sporotrichosis and characteristics of the infection include:

  • Once the mold spores move into the skin, the disease takes days-to-months to develop.
  • The first symptom 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. 
    • The disease can infect the bones, joints, lungs, and brain.
    • Such spreading usually occurs only in people with a weakened immune system.
    • These infections can be life threatening and are difficult to treat.

When to Seek Medical Care for Sporotrichosis

When to call the doctor

  • If you think you might have sporotrichosis, see a doctor about diagnosis and treatment.
  • If you are already being treated for sporotrichosis, contact a doctor if new sores develop or if the old ones appear to be growing.

When to go to the hospital

  • Sporotrichosis in the skin or lymph nodes should not be dangerous or life threatening.
  • Open ulcers can become infected with bacteria and may cause a condition known as cellulitis.
  • If a rapidly expanding area of redness, pain, and warmth around the original ulcers develops, you should go to a hospital's emergency department.

Exams and Tests for Sporotrichosis

Other infections can mimic sporotrichosis, so a doctor performs tests to confirm the diagnosis. The tests for sporotrichosis usually involve a biopsy of one of the nodules followed by an exam of the biopsy sample under a microscope to identify the mold. Other possible infections might include:

  • Bacteria related to tuberculosis or leprosy
  • Cowpox
  • Herpes
  • Other fungi and bacteria
  • Noninfectious diseases such as lupus

WebMD Medical Reference

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