Spatial, temporal, and meteorological distribution of Leptospira serogroups in humans and animals in Ukraine (2018–2023)

Leptospirosis is a globally important zoonotic disease whose transmission is influenced by environmental and meteorological conditions. In Ukraine, its epidemiology is further influenced by geographic heterogeneity and recent socio-environmental changes. This study aimed to describe the spatial and temporal distribution of Leptospira serogroups in humans and animals and to investigate their associations with regional meteorological variables. We analyzed national surveillance data from Ukraine for the period 2018–2023, including 1,332 human and 2,440 animal Leptospira serogroup identifications. Regional meteorological data-average annual temperature, total precipitation, and the annual number of rainy days-were integrated at the oblast level. Descriptive analyses were used to assess spatial and temporal variation in serogroup distribution. Correlation analyses were performed to explore associations between precipitation and serogroup counts. A multinomial logistic regression model was used to assess whether meteorological variables were differentially associated with individual human Leptospira serogroups. Icterohaemorrhagiae and the “Others” category were the most frequently identified serogroups in humans, each accounting for 30.2% of detections, while animal data showed greater serogroup diversity. Hebdomadis and Pomona in humans were positively correlated with average annual precipitation ( r = 0.36 and 0.32, respectively; p < 0.001). In the multinomial regression, average annual precipitation and average annual temperature were both significantly associated with serogroup composition ( p < 0.001 for both): relative to Icterohaemorrhagiae, higher precipitation specifically increased the relative risk of Hebdomadis and Pomona (RRR = 1.64 and 1.66, respectively; p < 0.001 for both), while higher temperature most strongly increased the relative risk of the “Others” category and Pomona. The distribution of Leptospira serogroups in Ukraine varies across regions and over time and is associated with key meteorological factors. Temperature and the frequency of precipitation events appear to have greater associations with leptospirosis incidence than cumulative rainfall. These findings improve understanding of the ecological determinants of leptospirosis and could support the development of climate-informed surveillance and early warning strategies.