The Centers for Disease Control and Prevention (CDC) in the United States recently released a warning about the spread of feline-transmitted sporotrichosis, a fungal disease that generally affects the skin. This disease is caused by a group of fungi from the genus Sporothrix, most commonly found in tropical and subtropical regions. Cat-transmitted sporotrichosis (CTS) has been a zoonotic epidemic (cat-to-human spread) in Brazil since the 1990s.

Human cases in Brazil have been predominantly caused by the species Sporotrichrix brasiliensis, with spillover to neighboring Argentina. CTS can be spread to humans via bites, scratches, or direct contact with infected lesions, as well as contaminated soil, plants, or organic matter. The most common presentation in humans is ulcerated lesions of the hands or arms, but this disease can progress to the pulmonary system or cause systemic disease, especially in immunocompromised people.

This CDC warning stems from a recent publication in Medical Mycology Case Reports describing the first 3 human cases ever reported in the UK of CTS caused by S. brasiliensis.

A brief summary of the report:

• Two of the human patients who resided in the same household (had moved from Brazil 3 years prior) presented to their local infectious disease clinic for various skin lesions (which included painless nodules and non-healing ulcerations of the skin). Their symptoms completely resolved after a long course of oral antifungal medication (Itraconazole). A 9-year-old child who also lived in the house remained asymptomatic.
• These aforementioned patients had migrated to the UK with their 9-year-old male, neutered long-haired domestic cat, originally from Brazil. This pet developed head and paw lesions 4 months prior to the human cases in the same household. Biopsies were submitted confirming pyogranulomatous inflammation consistent with a zoonotic fungal infection. The cat improved on Itraconazole. A second cat also lived in the household and had no clinical signs.
• The third human patient who developed skin lesions was a veterinarian in his late 20s who was treating the cat. His skin condition resolved after a long course of Itraconazole.

What information was gathered from this case report?

• This outbreak likely originated from the imported cat that was colonized with S. brasiliensis. Small skin lesions or asymptomatic carriage of the fungus would not be detected during veterinary health checks at border control.
• Methods to prevent future spread could include voluntary pre-import screening for sporotrichosis as an enzyme-linked immunosorbent assay (ELISA) has been developed in Brazil for detection of Sporothrix spp.
• Veterinarians who are seeing imported cats with skin conditions should inquire with their owners about the presence of any human skin lesions, especially after a history of feline bites or scratches.

Reviewed by Brian J. Peters, DVM. May 2023.