Emerging Zoonotic Sporotrichosis in Fortaleza, Brazil: Spatiotemporal Distribution, Exploratory Machine Learning Risk Modeling, and One Health Implications of Sporothrix brasiliensis Detection

Zoonotic sporotrichosis caused by Sporothrix brasiliensis is an emerging public health threat in Brazil. Under a One Health perspective, this study described the temporal and geographic distribution of recorded feline sporotrichosis detections in Fortaleza (2022–2026), as well as their co-occurrence with human notifications. Additionally, the study explored associations with socio-environmental factors and evaluated predictive performance at both the neighborhood and individual-animal levels. Suspected cats underwent cytology, culture, and species-specific calmodulin PCR. Cases were mapped across 116 neighborhoods, and logistic regression and random forest models were evaluated exploratorily at the neighborhood (61 neighborhoods) and animal (239 cats) levels, using grouped nested cross-validation and Spearman correlations corrected for multiple testing. Of 246 cats, 120 were confirmed, and all 37 isolates analyzed were S. brasiliensis. Neighborhoods with cases rose from one (2022) to 34 (March 2026), with 68 human notifications in 25 neighborhoods. After grouped validation, none of the evaluated predictor–outcome contrasts met the significance criterion after BY adjustment, and the exploratory associations were subject to substantial uncertainty. Consequently, no model demonstrated meaningful discriminative performance (out-of-sample AUC-ROC 0.34–0.50 at the neighborhood level and 0.38–0.47 at the animal level). These results are consistent with the complex, multifactorial nature of the disease, in which host behavior, environmental persistence, and surveillance intensity likely interact. These findings confirm the urban establishment of S. brasiliensis and the need for more complete data and robust analytical approaches. Outbreak control requires integrated One Health strategies: expanded access to diagnosis, cat neutering, and strengthened surveillance.