ROSE THORN DISEASE
(SPOROTRICHOSIS)

Consulting Rosarian: Mary Peterson, Horseheads, NY


Sporotrichosis is an infection caused by a fungus called Sporothrix schenckii which is found in vegetation. It usually infects the skin of people handling thorny plants, sphagnum moss or baled hay (or a combination of these). Outbreaks have been found occurring among nursery workers handling sphagnum moss, rose gardeners, children playing on baled hay and greenhouse workers handling bayberry thorns contaminated by the fungus or mulch-rich soil. A number of cases were reported among nursery workers especially those handling sphagnum moss topiaries and has been reported in all parts of the world.

The fungus enters the skin through small cuts or punctures from thorns, barbs, pine needles, splinters or wires from contaminated sphagnum moss, moldy hay, other plant materials or soil.

The infection manifests itself as small painless lumps or bumps resembling an insect bite 1-12 weeks after exposure. Usually the first appearance is within 3 weeks after initial infection. The lumps become open sores. The ulcers fail to heal and the micro-organisms which caused them enter the lymphatics and can move along the lymphatic system eventually infecting lungs, joints or the central nervous system. This dissemination can cause serious illness, especially in people with immuno-deficiencies. The disease cannot be spread from person to person. While the primary infection may be limited to the skin, infections of joints (osteomyelitis, arthritis), lung and central nervous system (meningitis), are possible but are very rare.




Rose Thorn Disease

The infected site can be red, pinkish or purple in color. The bump usually appears on the finger, hand or arm where the fungus first entered through a break in the skin. This is followed by one or more additional bumps, which can break open and resemble boils. Eventually they look like open sores that are very slow to heal. The infection can then be spread to other areas of the body.

Diagnosis is made when a doctor obtains a swab or biopsy of a freshly opened bump and it is sent to the laboratory for fungus culture. It is important that the infection is properly diagnosed so that treatment can be started as soon as possible.



The traditional form of treatment was potassium iodide taken orally three times a day in liquid form. A newer medication is called itraconazole (Sporanox). It is available for treatment and is the first choice as it causes fewer side effects than potassium iodide. Treatment may extend over several weeks until all the skin lesions are healed completely and extended for a month after the last lesion is healed, to prevent recurrence.

It is important for the rosarian to be vigilant when working with soil amendments that can carry the disease. Use gloves and long sleeves when handling wires, rose bushes, hay bales, pine seedlings or any other materials that might cause even minor skin breaks. It is also advisable to avoid skin contact with sphagnum moss. Moss has been implicated as a source of the fungus in a number of cases.