Zoonotic Sporotrichosis outbreak: Emerging public health threat in the Amazon State, Brazil

Background Sporotrichosis is the most common subcutaneous mycosis caused by Sporothrix spp. Traditionally, it is transmitted through injuries involving plant debris. However, over the past few decades, there has been an epidemic increase in human cases resulting from contact with infected animals, particularly cats, in various regions of Brazil. In this report, we report a notable increase in both human and animal cases within the Brazilian Amazon state.Methodology/Principal findings An ecological study was conducted by analyzing official records of human and animal sporotrichosis diagnosed in the state of Amazon from 2020 to 2023. Data including patient demographics, clinical manifestations, mycological examination results, and species identification through PCR confirmation were evaluated. During this period, a total of 950 human cases and 2,823 animal cases of sporotrichosis were reported at an exponential rate, since no human cases were registered in 2020. The spatial and temporal dispersion of human sporotrichosis followed that of animal cases, moving from downtown areas to the periphery. Contact with infected animals was reported in 77.7% of cases, with cats being the most commonly implicated (73.5%). Only 66.7% of individuals underwent mycological examination. Among the positive cultures for Sporothrix spp., 65.4% were identified as S. brasiliensis. All patients were treated with systemic antifungals.Conclusions/Significance This study highlights a rising incidence of sporotrichosis among animals and humans in the Brazilian Amazon region over the past four years, with S. brasiliensis being the predominant agent. Collaborative efforts involving healthcare professionals, veterinarians, and public health authorities are crucial to implement effective control measures, educate populations at risk, and promote responsible guidance for pet guardians. These measures are essential to mitigate the burden of epidemic sporotrichosis in Brazil. Sporotrichosis is the leading subcutaneous mycosis worldwide. In the last decades, Brazil has faced an epidemic of zoonotic cases. The Brazilian Amazon region had no human cases reported in 2020, nevertheless, a striking rise in both human and animal cases was observed from 2020 to 2023, totalizing 950 human and 2,823 animal sporotrichosis. The majority of cases were reported in Manaus, the largest city in the Amazon, but cases were also documented in other populous municipalities. The study emphasizes the correlation between animal and human cases, as well as the spatial and temporal progression of the disease, moving from downtown areas to the periphery. Cats were identified as the primary reservoirs, with contact with infected animals being a significant risk factor for transmission. Urban areas, particularly domestic environments, were identified as common sites of infection. The predominant species identified was Sporothrix brasiliensis, which exhibits distinct characteristics favoring zoonotic transmission. This study emphasizes the urgent need for collaborative efforts among healthcare professionals, veterinarians, and public health authorities to implement effective control measures and mitigate the impact of the epidemic sporotrichosis in Brazil.