Sporotrichosis

Cats are susceptible to a variety of fungal infections, including blastomycosis, histoplasmosis, cryptococcosis, candidiasis, dermatophytosis, aspergillosis, coccidioidomycosis, and sporotrichosis.

Sporotrichosis is a neglected fungal disease of humans and animals that remains a serious public-health problem. Sporothrix infections persist in cats, leading to continued transmission via cat-to-cat and cat-to-human contact. Cats are the major source of transmission of Sporothrix brasiliensis to the human population. Early diagnosis of feline sporotrichosis is critical to recognize outbreaks areas and effectively tackle future spread of the disease among humans. Most human cases occurred in housewives and professionals who had contact with infected animals and a history of scratches or bites.

Sporothrix schenckii is commonly found in soil and on plants. Feline habits render cats more susceptible to the fungal agent because they are constantly in contact with soil, plant debris, and other cats that may be infected. The skin infection that gains access through a break in the skin. Other routes of infection are by ingestion or inhalation of spores. The disease is most common among male cats that prowl in thorny underbrush or sharp prairie grass. Most cases are reported in the northern and central portions of the United States.

Siamese cats seem to be more predisposed to develop the infection than most other breeds. Entire male cats under 4 years of age often get infected during fights with other males.

There are two forms of the infection. Plaque sporotrichosis occurs if the infection is localized at the site of puncture. Disseminated sporotrichosis&mdash occurs when the infection is spread to lymph nodes, joints, eyes, and meninges. Individuals with chronic diseases such as diabetes mellitus, HIV, or cats who are given glucocorticoids are especially predisposed to develop disseminated form of sporotrichosis.



A nodule forms at the site of a skin wound, usually on the feet and legs, face or base of tail. The hair over the nodule falls out, leaving a most ulcerated surface. In some cases there is a little surface reaction, but you may see several small firm nodules beneath the skin that appear to form a chain. Skin necrosis may occur to reveal the underlying muscle. Normal grooming may spread the infection to other parts of the body.

On rare occasions the disease spreads internally to the liver and lungs. In these individuals the outlook for cure is guarded. The diagnosis is made by removing a piece of tissue and examining it under the microscope; or growing the fungus in culture.

The reponse to treatment is excellent when disease is limited to the skin and surrounding tissues. Potassium iodide is the agent of choice. ketoconazole and Itraconazole also have been used. Amphotericin B is used for internal infection. These drugs have toxic potential and require close veterinary supervision.

Sporotrichosis effects on human skin
Fungal disease sporotrichosis
caused by the fungus Sporothrix schenckiiImage provider: CDC/Dr. Lucille K. Georg

CAUTION: Sporotrichosis has been known to infect humans handling cats with infective drainage from nodules and ulcers. Wear rubber gloves and use strict hygienic precautions when handling cats with draining wounds.

The first symptom is usually a small painless bump that's red, pink, or purple. This is followed by one or more additional bumps/nodules which open and may resemble boils. Eventually lesions look like open sores, or ulcerations, and heal slowly.

Most cases of sporotrichosis occur in people who work with plants or contact infected cats. Some outbreaks have been linked to contaminated sphagnum moss, hay, or wood. Disseminated sporotrichosis is a serious, potentially life-threatening disease with a grave prognosis. Disseminated sporotrichosis appears to be more common in people with underlying conditions such as alcoholism, diabetes, cancer, or suppressed immune system. 1

References

  1. Sporotrichosis. Rose Handler's Disease
  2. Proteomics-Based Characterization of the Humoral Immune Response in Sporotrichosis: Toward Discovery of Potential Diagnostic and Vaccine Antigens. Anderson Messias Rodrigues et al. 2015





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