Emerging fungal zoonoses: pets, cities and antifungal resistance are reshaping One Health risks

Closer contact between people and companion animals, urbanisation and changing environmental conditions are altering the epidemiology of fungal zoonoses, according to a new 2026 review. Dogs and cats can act as reservoirs for dermatophytes and other fungi, while shared environments expose both animals and humans to systemic mycoses. The authors also warn that inappropriate antifungal use could accelerate resistance.

The review, examines fungal infections associated with companion animals and the environmental conditions that favour transmission. It places these diseases firmly within a One Health framework linking pets, owners and their shared environment.

Dermatophytosis remains the main pet-associated fungal zoonosis

Dermatophytosis (ringworm) is described as the most common superficial fungal zoonosis affecting pets. In cats and dogs, Microsporum canis is the dominant species, with cats acting as an important reservoir and sometimes carrying the fungus without obvious lesions. Other relevant dermatophytes include Trichophyton mentagrophytes and Nannizzia species.

Transmission can occur through direct contact with infected skin and hair, but also indirectly through bedding, grooming equipment, furniture and other contaminated surfaces. Fungal arthroconidia may remain infectious in the environment, allowing transmission even without immediate animal contact.

Cats play a key role in sporotrichosis

The review also highlights sporotrichosis, particularly infection with Sporothrix brasiliensis. Cats are epidemiologically important because lesions may contain very high fungal burdens and transmission to humans can occur through scratches, bites or direct contact with exudates.

This cat-associated transmission cycle has become an important emerging zoonotic problem, particularly in Latin America, and illustrates how a traditionally environmental fungus can develop efficient animal-to-human transmission.

Environment remains central to systemic mycoses

Not all fungal infections pass directly from pets to owners. Aspergillus, Cryptococcus and Histoplasma, for example, are primarily acquired from environmental reservoirs such as soil, decaying organic matter or material contaminated with bird or bat droppings. Humans and animals may therefore become infected independently after exposure to the same environment.

The authors argue that urban development, soil disturbance, increasing pet density and rising temperatures may modify these exposure patterns. Climate-driven selection for fungal thermotolerance could also favour species better able to survive at mammalian body temperatures.

Antifungal resistance becomes a veterinary issue

Another concern is treatment pressure. Inadequate dosing, premature discontinuation of therapy and repeated antifungal exposure may reduce treatment success and favour resistant fungal populations. The review points specifically to emerging antifungal-resistant dermatophytes, while also stressing the wider problem of antimicrobial resistance circulating between companion animals, humans and household environments.

Better diagnosis, appropriate antifungal use, environmental decontamination, owner education and coordinated human–veterinary surveillance will become increasingly important as pet populations grow and human–animal contact intensifies.