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Sporotrichosis

	A photomicrograph showing the conidiophores and conidia of the fungus Sporothrix schenckii.

A photomicrograph showing the conidiophores and conidia of the fungus <em>Sporothrix schenckii</em>.

Sporotrichosis is an infection caused by a fungus called Sporothrix schenckii. The fungus lives throughout the world in soil, plants, and decaying vegetation. Cutaneous (skin) infection is the most common form of infection and usually occurs after handling contaminated plant material, when the fungus enters the skin through a small cut or scrape.

Fungal infections pose an increasing threat to public health for several reasons. For other Fungal topics, visit the Fungal Homepage.

Definition

Sporotrichosis is an infection caused by a fungus called Sporothrix schenckii. The fungus lives throughout the world in soil, plants, and decaying vegetation. Cutaneous (skin) infection is the most common form of infection, although pulmonary infection can occur if a person inhales the microscopic, airborne fungal spores. Most cases of sporotrichosis are sporadic and are associated with minor skin trauma like cuts and scrapes; however, outbreaks have been linked to activities that involve handling contaminated vegetation such as moss, hay, or wood.

Symptoms

The first symptom is usually a small painless nodule (bump) resembling an insect bite. The first nodule may appear any time from 1 to 12 weeks after exposure to the fungus. The nodule can be red, pink, or purple in color, and it usually appears on the finger, hand, or arm where the fungus has entered through a break in the skin. The nodule will eventually become larger in size and may look like an open sore or ulcer that is very slow to heal. Additional bumps or nodules may appear later near the original lesion.

Most Sporothrix infections only involve the skin. However, the infection can spread to other parts of the body, including the bones, joints, and the central nervous system. Usually, these types of disseminated infections only occur in people with weakened immune systems. In rare cases, a pneumonia-like illness can occur after inhaling Sporothrix spores, which can cause symptoms such as shortness of breath, cough, and fever.

If you think you have sporotrichosis, you should see a healthcare provider.

Risk & Prevention

Who gets sporotrichosis?

People who handle thorny plants, sphagnum moss, or bales of hay are at increased risk of getting sporotrichosis. The infection is more common among people with weakened immune systems, but it can also occur in otherwise healthy people. Outbreaks have occurred among florists, plant nursery workers who have handled sphagnum moss, rose gardeners, children who have played on bales of hay, and greenhouse workers who have handled thorns contaminated by the fungus.

How can I prevent sporotrichosis?

There is no vaccine to prevent sporotrichosis. You can reduce your risk of sporotrichosis by wearing protective clothing such as gloves and long sleeves when handling wires, rose bushes, bales of hay, pine seedlings, or other materials that may cause minor cuts or punctures in the skin. It is also advisable to avoid skin contact with sphagnum moss.

Sources

The fungus lives in sphagnum moss, hay, other plant materials, and soil. The fungus can enter the skin through small cuts or punctures from thorns, barbs, pine needles, or wires. In rare cases, inhalation of the fungus can cause pulmonary infection. Sporotrichosis is not spread from person to person; however, a small number of human cases have been caused by scratches or bites from infected animals such as cats.

You can learn more about cat-transmitted diseases at the CDC's Healthy Pets Healthy People web site.

Diagnosis and Testing

	This photomicrograph shows Sporothrix schenckii in a smear obtained from a rat

This photomicrograph shows <em>Sporothrix schenckii</em> in a smear obtained from a rat

Sporotrichosis is typically diagnosed when your doctor obtains a swab or a biopsy of the infected site and sends the sample to a laboratory for a fungal culture. Serological tests are not always useful in the diagnosis of sporotrichosis due to limitations in sensitivity and specificity.

Treatment and Outcomes

Most cases of sporotrichosis only involve the skin and/or subcutaneous tissues and are non-life-threatening, but the infection requires treatment with prescription antifungal medication for several months. The most common treatment for this type of sporotrichosis is oral itraconazole for 3 to 6 months. Itraconazole may also be used to treat bone and joint infections, but treatment should continue for at least 12 months.

For patients with severe disease, and/ or an infection that has spread throughout the body, a lipid formulation of amphotericin B should be used. Itraconazole can be used for step-down therapy once the patient has stabilized. Supersaturated potassium iodide (SSKI) is another treatment option for cutaneous or lymphocutaneous disease. SSKI and azole drugs like itraconazole should not be used during pregnancy. Treatment recommendations may differ for children.

For healthcare providers: the most up-to-date treatment and practice guidelines can be found at the Infectious Disease Society of America's [PDF - 11 pages] web site.

Statistics

The exact incidence of sporotrichosis is unknown, but people at increased risk for sporotrichosis usually have occupational or recreational exposures related to agriculture, horticulture, forestry, or gardening.

Sporothrix schenckii can be found throughout the world in soil and plant matter. Peru is suspected to be an area where S. schenckii is extremely common in the environment. Outbreaks of sporotrichosis have been documented in the United States, Western Australia, and Brazil.

Additional Information

MMWR Articles:

Sporotrichosis Associated with Wisconsin Sphagnum Moss. MMWR Weekly, October 15, 1982/31(40); 542-4.

Multistate Outbreak of Sporotrichosis in Seedling Handlers, 1988. MMWR Weekly, October 28, 1988/37(42); 652-3.

Sporotrichosis Among Hay-Mulching Workers – Oklahoma, New Mexico. MMWR Weekly, December 7, 1984/33(48); 682-3.

Publications:

Kauffman CA, Hajjeh R, and SW Chapman. 2000. Practice Guidelines for the Management of Patients with Sporotrichosis. Clinical Infectious Diseases. 30(4): 684-687.

Neyra E, Fonteyne P, Swinne D, Fauche F, Bustamante B, and N Nolard. 2005. Epidemiology of Human Sporotrichosis Investigated by Amplified Fragment Length Polymorphism. Journal of Clinical Microbiology. 43(3): 1348-1352.

Pappas PG, TellezI, Deep AE, Nolasco D, Holgado W, and B. Bustamante. 2000. Sporotrichosis in Peru: Description of an area of hyperendemicity. Clinical Infectious Diseases. 30:65-70.

Schubach A, Schubach TMP, de Lima Barros MB, and B Wanke. 2005. Cat-transmitted sporotrichosis, Rio de Janeiro, Brazil. Emerging Infectious Diseases.

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