The infection develops when the fungi enter the body through small cuts and scrapes in the skin.
Usually, the skin and nearby lymph nodes are infected, resulting in bumps on the skin and swollen lymph nodes.
Rarely, the lungs, joints, or other parts of the body are infected.
Diagnosis requires culture and identification of the fungus in a sample of infected tissue.
Itraconazole is used to treat most infections, but amphotericin B is required for bodywide infections.
(See also Overview of Fungal Infections.)
Sporothrix fungi typically grow on rose bushes, barberry bushes, sphagnum moss, and other mulches. In contrast to many other fungal infections, Sporothrix fungi enter the body through small cuts and scrapes in the skin. Most often, farmers, gardeners, horticulturists, and timber workers are infected.
Sporotrichosis affects mainly the skin and nearby lymphatic vessels.
Very rarely, a lung infection occurs after spores are inhaled.
Also very rarely, bones, joints, or the brain and spinal cord are infected, usually in people with a weakened immune system, such as those with AIDS.
In sporotrichosis, an infection of the skin typically starts on a finger or hand as a small, painless bump (nodule). The bump slowly enlarges and forms an open sore.
Over the next several days or weeks, the infection spreads through the lymphatic vessels of the finger, hand, and arm to the lymph nodes, forming more nodules and open sores along the way. Pus from the lymph nodes may break through the skin, causing an opening that infected material drains through. Even at this stage, there is little or no pain. Usually, people have no other symptoms. This infection is seldom fatal.
Other symptoms are rare. An infection in the lungs may cause pneumonia, with a slight chest pain and cough. Lung infection usually occurs in people who have another lung disorder, such as emphysema.
Joint infection causes swelling and makes movement painful.
Very rarely, sporotrichosis spreads throughout the body. Such infections are life threatening and are more common among people with a weakened immune system.
The characteristic nodules and sores may lead a doctor to suspect sporotrichosis, especially when people may have been exposed to the fungus (for example, gardeners, landscapers, and foresters).
The diagnosis is confirmed by growing (culturing) and identifying Sporothrix in samples of infected tissue.
Skin infections are treated with itraconazole given by mouth.
If the infection is severe, amphotericin B is given intravenously followed by itraconazole. Treatment takes 1 year altogether.
After the infection is controlled, people with AIDS or another condition that weakens the immune system may need to take itraconazole by mouth until their immune system has recovered, possibly for the rest of their life. Itraconazole helps prevent sporotrichosis from recurring while the immune system is weak.