Sporothrix brasiliensis as the major causative species of the zoonotic outbreak of human sporotrichosis in the Brazilian Amazon.

Background: Sporotrichosis is a neglected tropical disease and the most common subcutaneous mycosis, mainly caused by Sporothrix species, particularly S. brasiliensis, S. schenckii and S. globosa, which exhibit varying biological behaviours and virulence. The epidemic of sporotrichosis in Brazil, initiated in Rio de Janeiro in the late 1990s, rapidly spread to other states, including Amazonas in 2021. This study aimed to identify the specific Sporothrix species responsible for the human sporotrichosis outbreak in the Brazilian Amazon.

Methods: A cross-sectional study was conducted by enrolling clinically suspected cases of sporotrichosis attended at a reference dermatologic centre, in Manaus (Brazil). Biological material was collected from their skin lesions for culture (Mycosel) and for species identification (qPCR).

Results: Sporothrix cultures were obtained from 150 cases. Sporotrichosis predominantly affected females (67.3%), aged 44.5 years on average, with lymphocutaneous lesions (72.7%). Sporothrix brasiliensis was identified in 89.3% of patients. Up to 83.3% of these patients reported contact with cats previously to the skin lesion, and the time-spatial progression of the human cases followed the notification of cases in cats, in the metropolitan region of Manaus.

Conclusion: Sporothrix brasiliensis is the dominant species in the zoonotic outbreak of human sporotrichosis in the Brazilian Amazon, with cats identified as the primary vectors. Effective sanitary control measures, education and responsible pet ownership are crucial to mitigating zoonotic sporotrichosis' impact in Brazil and preventing its spread to neighbouring Latin American cities.