Sporothrix mold phase	Sporothrix yeast phase

Sporothrix schenckii is found worldwide in soils rich in decaying organic matter and is transmitted by penetrating injury or contact with plant or soil. In dogs, infection is associated with puncture wounds by thorns or wood splinters. In cats, Sporothrix infection is associated with intact male cats that roam and have inoculation of the organism by claw of another cat. In humans, sporotrichosis is associated with contact exposure to cats infected with S. schenckii and contamination of a puncture wound. Sporothrix is considered an emerging zoonotic disease because it has only recently been found to be transmissible from cats to humans.

Animals

Sporotrichosis in dogs, cats and horses is a multinodular condition on the trunk or head. Nodules are in the dermal and subcutaneous tissues and there may or may not be ulcerations involved.

The nodules can have purulent exudates and crusting.

There is also a cutaneolymphatic form that involves nodules on the distal aspect of one limb with an infection that ascends with secondary nodules developing and lymphadenomegaly. In cats most nodules are found at the distal aspects of the limbs, tail or head. The cat presents with draining puncture wounds that are large crusted lesions. A history of treatment with antibiotics without improvement may be present. Cats can spread the lesion all over themselves with their grooming. Most cats have the disseminated form of the disease. Lesions may be secondarily infected with Staphylococcus intermedius.

Diagnosis: Exudate from the lesions should be stained and examined for the Sporothrix organism.

It is easier to find the organism in cats than dogs due to the increased numbers of organisms found in the nodules of cats. Culture from deep within the nodule is important in the diagnosis of the dog.

Treatment: Dogs can be treated with a supersaturated solution of potassium iodide (side effects: scaling, vomiting, discharge) or Ketoconazole or Itraconazole (hepatotoxic) for 30 days beyond resolution of clinical signs. Cats are treated with Itraconazole for 30 days beyond clinical cure. Any animal on ketoconazole or intraconazole should have liver enzymes monitored for early determination toxicity.

Humans

Most cases of human sporotrichosis have been diagnosed in veterinarians.

Transmission occurs via contact with infected wound or exudates from an infected cat. Thus far cats only are responsible for zoonotic transmission to humans due to the high numbers of Sporothrix organisms found in their nodules. Infection can occur with nontraumatic exposure to infected cat without a preexisting penetrating wound. Disease in humans begins with a nodule or pustule where the skin was broken. The infection may stay local or can spread and form nodules along the enlarged lymph ducts. The nodules may ulcerate. Rarely, disseminated forms of sporotrichosis occur affecting the bones, joints, mouth, nose, or kidneys.

Diagnosis is made with biopsy, cytology, or fungal culture.

Sporothrix in slide culture

Prevention: Wear disposable gloves when handling cats with ulcerating nodules, and wash hands, wrists, and forearms with chlorhexidine or povodone iodine.

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