Flesh-Eating Fungus Jumping from Cats to Humans Is Spreading at an Alarming Rate
A stubborn fungal infection once linked to a very different kind of exposure is now appearing in cats and humans, with signs of a larger regional spread.
A Flesh-Eating Fungus Spreading from Cats to Humans Has Been Detected, and It's Expanding Fast
Health officials are sounding the alarm over a growing number of cases involving Sporothrix brasiliensis, a fungal pathogen capable of causing disfiguring skin lesions and, in severe instances, life-threatening systemic infections. Originally concentrated in Brazil, where it has been spreading among stray and domestic cat populations for decades, the organism has now been detected in several new regions, raising concerns that a global expansion is underway. Unlike traditional forms of sporotrichosis, which people typically contract through contact with soil or plant matter, this strain passes readily from cats to humans through scratches, bites, or even close contact with infected animals. Public health experts warn that the speed and scale of the spread have caught many off guard.
Cats appear to be uniquely efficient carriers of the fungus. Infected felines often develop severe, ulcerating wounds around the face and limbs, shedding massive quantities of fungal cells from their lesions. Veterinarians in affected areas report that shelters and clinics are seeing a sharp uptick in cases, particularly among free-roaming cats in densely populated urban neighborhoods. When humans contract the infection, it typically begins as a small, painless bump that gradually swells into an open, necrotic sore that resists healing without antifungal treatment. In immunocompromised individuals, the fungus can disseminate to bones, joints, and internal organs, sometimes with fatal consequences.
The geographic reach of S. brasiliensis has expanded significantly in recent years. Cases have been confirmed in parts of Argentina, Paraguay, and the United Kingdom, and suspected cases have surfaced in other countries as international cat adoption and travel continue to rise. Researchers at the Oswaldo Cruz Foundation in Rio de Janeiro, who have tracked the pathogen for years, say its ability to transmit directly between mammals sets it apart from nearly all other pathogenic fungi and makes containment far more difficult. Standard antifungal medications such as itraconazole remain effective in many cases, but treatment courses can last months, and emerging drug resistance has been documented in some isolates.
Public health authorities are urging cat owners and veterinary professionals to remain vigilant for signs of infection, particularly unusual skin lesions that do not respond to antibiotics. Early diagnosis and prompt treatment are critical both for the welfare of affected animals and for preventing transmission to people. Experts are calling for increased surveillance, better reporting systems, and coordinated international efforts to track the fungus before it becomes firmly established in new regions. Without decisive action, they warn, Sporothrix brasiliensis could become a persistent and expanding threat to both animal and human health worldwide.