Environmental risk factors and spatial patterns of Fasciola hepatica infection in herbivores from Salta and Jujuy provinces, Argentina.

Fasciolosis, caused by Fasciola hepatica, is a snail-borne zoonotic disease of major veterinary importance, responsible for significant economic losses in livestock. Its transmission is strongly influenced by environmental and climatic conditions. In northwestern Argentina, particularly in Salta and Jujuy provinces, the disease is endemic; however, the environmental and spatial determinants of its distribution remain incompletely understood. This study aimed to identify environmental risk factors and spatial patterns associated with F. hepatica infection in herbivores to better understand its epidemiological dynamics and support targeted control strategies. A retrospective analysis was conducted using coproparasitological records from 1994 to 2025 from livestock in both provinces. A total of 12,465 fecal samples from multiple host species were analyzed. The infection status was related to climatic variables, topography, and edaphic characteristics. Temporal variability and clear seasonal patterns were observed, with higher positive frequency in late winter-early spring. In the multivariate analysis, higher soil pH, sand and silt content, and cation exchange capacity were positively associated with infection, while bulk density and soil organic carbon were negatively associated. Spatial analysis identified nine significant clusters, including a main high-risk cluster in the central-western region of Salta and the central-southern region of Jujuy provinces, as well as several smaller focal clusters with increased relative risk. These findings demonstrate that fasciolosis distribution is non-random and driven by the interaction between soil properties, climate, host species, and spatial heterogeneity. The results provide a basis for risk-based surveillance and targeted control strategies adapted to local environmental conditions.