Doctor's Notes on Sporotrichosis
Sporotrichosis is a skin infection caused by the fungus Sporothrix schenckii; it has been termed “Rose handler’s disease”. Infection is often found in individuals (gardeners) that raise roses and/or work with moss and soil; the fungus is frequently located on the thorns of roses. Signs and symptoms of sporotrichosis may not appear for days to months. Signs and symptoms begin as firm nodule on the skin that range in color from pink to purple. These nodules can be painless or slightly tender. The nodules, over time, may develop into an open sore or ulcer and drain clear fluid. Often, the organisms develop along a straight line on an extremity that indicates lymph node infection; these infections may develop sinus tracks from the lymph node to the skin. These open sinus tracks are termed mycetomas; they may discharge granular material composed of mainly fungi. Rarely, the infection may reach one or more of the internal organs.
The cause of sporotrichosis is infection by the fungus Sporothrix schenckii. The disease is not spread person-to-person. Rarely, it can be transmitted to humans with scratches from animals’ claws or may be inhaled and/or ingested. The signs and symptoms can be more aggressive in immunosuppressed individuals.
- Once the fungal conidia (spores) are moved into the skin via thorns, scrapes, or other mechanisms, 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; in other instances, mycetomas may be formed. Mycetomas are areas where sinus tracts are formed from the lymph to the skin surface and discharge granules containing masses of organisms that cause the infection.
- Untreated, the nodule and the ulcer become chronic and may remain unchanged for years.
- In about 60% of cases, the fungus 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 symptoms are progressive. Initial sites of infection are not visibly distinctive. As the infection progresses, lesions develop, often appearing in a line as successive areas (lymph nodes) of the lymphatic channels become infected (compare figures below).
The disease, sporotrichosis, is caused by the fungus Sporothrix schenckii, although recent research has shown that several other distinct Sporothrix species also cause the disease. However, the disease progresses similarly for these closely related fungal species:
- Sporotrichosis usually begins when fungal spores are forced under the skin by a rose thorn or sharp stick.
- The infection may also begin in apparently unbroken skin after contact with hay or moss carrying the fungus.
- Farmers, nursery workers, landscapers, and gardeners are at higher risk for the disease because of their chance of cuts or puncture wounds while working with soil. People who are immunosuppressed (HIV patients, cancer patients, for example) are also at higher risk to get the disease.
- Rarely, cats or armadillos can transmit the disease to humans with scratches from the animal's claws.
- In very rare cases, the organism can be inhaled or ingested, leading to infection of parts of the body other than the skin. This type of systemic infection may also occur from advanced skin infections in people who are immunosuppressed.
- The disease is not transmitted from person to person, and some investigators consider sporotrichosis to be a self-limited mycosis (fungal infection not transmitted to other people).
The fungus is dimorphic (can exist as a yeast-like or hyphae-producing form). The figure below shows the hyphae (the long, filamentous parts) and conidia (spores) of Sporothrix schenckii.
Fungal skin infections can be itchy and annoying, but they're rarely serious. Common infections such as athlete's foot, jock itch, and ringworm are caused by fungus and are easy to get and to pass around. In healthy people, they usually don't spread beyond the skin's surface, so they're easy to treat. If you spend a lot of time at the gym, take steps to protect yourself against fungal infections.
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Ringworm is caused by a fungus.See Answer
Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.