{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,20]],"date-time":"2026-07-20T12:02:42Z","timestamp":1784548962648,"version":"3.55.0"},"reference-count":34,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2026,7,20]],"date-time":"2026-07-20T00:00:00Z","timestamp":1784505600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100018227","name":"Grant of the President of Ukraine for Young Scientists","doi-asserted-by":"publisher","award":["2025.05\/0012"],"award-info":[{"award-number":["2025.05\/0012"]}],"id":[{"id":"10.13039\/100018227","id-type":"DOI","asserted-by":"publisher"}]},{"name":"DAAD Research Grant in Germany"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Pathogens"],"abstract":"<jats:p>Background: Ukraine has substantial regional differences in climate, landscape, forest cover, and river networks, which may influence leptospirosis transmission. However, recent monthly oblast-level variation in leptospirosis incidence has not been systematically described. We used newly available surveillance data for 2023\u20132025 to assess seasonal and regional patterns of leptospirosis and their associations with weather, climatic zone, forest cover, and river network density. Methods: We analyzed surveillance data from 23 Ukrainian oblasts. Incidence was assessed by month, oblast, and climatic zone. Weather data were aggregated monthly; forest cover and river network density were included as predictors. Associations were assessed using correlation, cross-correlation, and Random Forest ML models. Results: Incidence showed a clear seasonal increase, reaching its highest levels in late summer and autumn, approximately one to three months after seasonal peaks in temperature and precipitation. The highest incidence was observed in Zakarpattia, Chernihiv, and Ternopil oblasts, while incidence by climatic zone was highest in the Carpathian group and lowest in the Steppe zone. Among weather variables, average temperature showed the clearest delayed association with leptospirosis incidence. River network density was the leading ecological predictor in the adjusted models. The positive unadjusted association between forest cover and incidence became negative after adjustment for river network density, suggesting that these variables captured overlapping ecological characteristics. In the Random Forest analysis, river network density was the top-ranked predictor, and the best-performing model achieved an AUC of 0.795. Conclusions: Leptospirosis incidence in Ukraine varied substantially by season and region. Delayed temperature effects, river network density, and forest cover were associated with regional risk. Monthly oblast-level surveillance with climatic and ecological data may help monitor leptospirosis risk, but war-related disruption to diagnosis and reporting should be considered.<\/jats:p>","DOI":"10.3390\/pathogens15070759","type":"journal-article","created":{"date-parts":[[2026,7,20]],"date-time":"2026-07-20T10:44:02Z","timestamp":1784544242000},"page":"759","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Regional and Seasonal Dynamics of Leptospirosis in Ukraine, 2023\u20132025"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-0860-4445","authenticated-orcid":false,"given":"Pavlo","family":"Petakh","sequence":"first","affiliation":[{"name":"Department of Biochemistry and Pharmacology, Uzhhorod National University, 88000 Uzhhorod, Ukraine"},{"name":"Kyiv School of Economics, 03113 Kyiv, Ukraine"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9028-7230","authenticated-orcid":false,"given":"Iryna","family":"Halabitska","sequence":"additional","affiliation":[{"name":"Department of Therapy and Family Medicine, I. Horbachevsky Ternopil National Medical University, 46001 Ternopil, Ukraine"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Oleh","family":"Lushchak","sequence":"additional","affiliation":[{"name":"Kyiv School of Economics, 03113 Kyiv, Ukraine"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3141-4436","authenticated-orcid":false,"given":"Oleksandr","family":"Kamyshnyi","sequence":"additional","affiliation":[{"name":"Kyiv School of Economics, 03113 Kyiv, Ukraine"},{"name":"Department of Microbiology, Virology, and Immunology, I. Horbachevsky Ternopil National Medical University, 46001 Ternopil, Ukraine"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,7,20]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Petakh, P., Tymchyk, V., and Kamyshnyi, O. (2024). Surveillance of human leptospirosis infections in Ukraine between 2018 and 2023. Front. Public Health, 12.","DOI":"10.3389\/fpubh.2024.1394781"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1422","DOI":"10.1038\/s41598-025-31138-3","article-title":"War, diet, and PTSD in Ukrainian youth","volume":"16","author":"Halabitska","year":"2025","journal-title":"Sci. Rep."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"e015440","DOI":"10.1136\/bmjgh-2024-015440","article-title":"Russian full-scale invasion of Ukraine: Epidemiological challenges for public health","volume":"11","author":"Chumachenko","year":"2026","journal-title":"BMJ Glob. Health"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"122","DOI":"10.1007\/s00284-026-04722-7","article-title":"Leptospira and Leptospirosis: A Review of Species Classifications, Genomes, Morphological Structures, Antimicrobial Resistances, Transmissions, and Clinical Manifestations","volume":"83","author":"Bilung","year":"2026","journal-title":"Curr. Microbiol."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"101158","DOI":"10.1016\/j.onehlt.2025.101158","article-title":"Detection of pathogenic Leptospira spp. in peridomestic Rattus norvegicus in Hong Kong","volume":"21","author":"Wen","year":"2025","journal-title":"One Health"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"7239","DOI":"10.1038\/s41598-020-64172-4","article-title":"Pathogenic Leptospira and their animal reservoirs: Testing host specificity through experimental infection","volume":"10","author":"Cordonin","year":"2020","journal-title":"Sci. Rep."},{"key":"ref_7","first-page":"65","article-title":"Leptospirosis in humans","volume":"387","author":"Haake","year":"2015","journal-title":"Curr. Top. Microbiol. Immunol."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"e9","DOI":"10.1590\/s1678-9946202668009","article-title":"Leptospirosis-associated pulmonary hemorrhagic syndrome: Immune mechanisms, clinical manifestations, and experimental models","volume":"68","author":"Silva","year":"2026","journal-title":"Rev. Inst. Med. Trop. Sao Paulo"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"e23473","DOI":"10.1016\/j.heliyon.2023.e23473","article-title":"Environmental and Occupational Factors Associated with Leptospirosis: A Systematic Review","volume":"10","author":"Baharom","year":"2024","journal-title":"Heliyon"},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Talukder, H., Mu\u00f1oz-Zanzi, C., Salgado, M., Berg, S., and Yang, A. (2024). Identifying the Drivers Related to Animal Reservoirs, Environment, and Socio-Demography of Human Leptospirosis in Different Community Types of Southern Chile: An Application of Machine Learning Algorithm in One Health Perspective. Pathogens, 13.","DOI":"10.20944\/preprints202407.1593.v1"},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Petakh, P., Oksenych, V., and Kamyshnyi, O. (2025). Prevalence of leptospirosis among soldiers: A systematic review. PLoS Negl. Trop. Dis., 19.","DOI":"10.1371\/journal.pntd.0012927"},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Leal Filho, W., Eustachio, J.H.P.P., Fedoruk, M., and Lisovska, T. (2024). War in Ukraine: An overview of environmental impacts and consequences for human health. Front. Sustain. Resour. Manag., 3.","DOI":"10.3389\/fsrma.2024.1423444"},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Cunha, M., Costa, F., Ribeiro, G.S., Carvalho, M.S., Reis, R.B., Nery, N., Pischel, L., Gouveia, E.L., Santos, A.C., and Queiroz, A. (2022). Rainfall and other meteorological factors as drivers of urban transmission of leptospirosis. PLoS Negl. Trop. Dis., 16.","DOI":"10.1371\/journal.pntd.0007507"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1486","DOI":"10.1038\/s41598-020-79546-x","article-title":"The effects of flooding and weather conditions on leptospirosis transmission in Thailand","volume":"11","author":"Chadsuthi","year":"2021","journal-title":"Sci. Rep."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"101671","DOI":"10.1016\/j.lanepe.2026.101671","article-title":"Spatiotemporal dynamics of leptospirosis in Europe: A retrospective observational study with prospective projections","volume":"65","author":"Fanelli","year":"2026","journal-title":"Lancet Reg. Health Eur."},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Costa, F., Hagan, J.E., Calcagno, J., Kane, M., Torgerson, P., Martinez-Silveira, M.S., Stein, C., Abela-Ridder, B., and Ko, A.I. (2015). Global morbidity and mortality of leptospirosis: A systematic review. PLoS Negl. Trop. Dis., 9.","DOI":"10.1371\/journal.pntd.0003898"},{"key":"ref_17","first-page":"2300266","article-title":"Epidemiology of reported cases of leptospirosis in the EU\/EEA, 2010 to 2021","volume":"29","author":"Innocenti","year":"2024","journal-title":"Eurosurveillance"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"1691122","DOI":"10.1155\/jama\/1691122","article-title":"Leptospirosis Dynamics with Misdiagnosis: A Review","volume":"2025","author":"Mwongela","year":"2025","journal-title":"J. Appl. Math."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"ftae006","DOI":"10.1093\/femspd\/ftae006","article-title":"From fever to action: Diagnosis, treatment, and prevention of acute undifferentiated febrile illnesses","volume":"82","author":"Barathan","year":"2024","journal-title":"Pathog. Dis."},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Petakh, P., Isevych, V., Kamyshnyi, A., and Oksenych, V. (2022). Weil\u2019s Disease-Immunopathogenesis, Multiple Organ Failure, and Potential Role of Gut Microbiota. Biomolecules, 12.","DOI":"10.3390\/biom12121830"},{"key":"ref_21","first-page":"199","article-title":"Leptospirosis diagnosis: Competancy of various laboratory tests","volume":"8","author":"Budihal","year":"2014","journal-title":"J. Clin. Diagn. Res. JCDR"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"719","DOI":"10.1093\/heapol\/czag049","article-title":"Health system response and recovery in Ukraine after 3 years of war: Perspectives of front-line communities and internally displaced persons","volume":"41","author":"Hellowell","year":"2026","journal-title":"Health Policy Plan."},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Zelinskyy, G., Koval, T., Schrammel, U., Elsner, C., Ackermann, J., Marchenko, O., Sydorenko, M., Shlykova, O., Izmailova, O., and Kabaliei, A. (2026). Establishing an EU-compliant diagnostic facility for infectious diseases under war conditions in Poltava, Ukraine. Front. Public Health, 14.","DOI":"10.3389\/fpubh.2026.1840777"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"100944","DOI":"10.1016\/j.onehlt.2024.100944","article-title":"Geographical factors and air raid alarms influence leptospirosis epidemiology in Ukraine (2018\u20132023)","volume":"19","author":"Petakh","year":"2024","journal-title":"One Health"},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Valente, M., Bramugy, J., Keddie, S.H., Hopkins, H., Bassat, Q., Baerenbold, O., Bradley, J., Falconer, J., Keogh, R.H., and Newton, P.N. (2024). Diagnosis of human leptospirosis: Systematic review and meta-analysis of the diagnostic accuracy of the Leptospira microscopic agglutination test, PCR targeting Lfb1, and IgM ELISA to Leptospira fainei serovar Hurstbridge. BMC Infect. Dis., 24.","DOI":"10.1186\/s12879-023-08935-0"},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Desvars, A., J\u00e9go, S., Chiroleu, F., Bourhy, P., Cardinale, E., and Michault, A. (2011). Seasonality of human leptospirosis in Reunion Island (Indian Ocean) and its association with meteorological data. PLoS ONE, 6.","DOI":"10.1371\/journal.pone.0020377"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"311","DOI":"10.3201\/eid2602.190102","article-title":"Influence of Rainfall on Leptospira Infection and Disease in a Tropical Urban Setting, Brazil","volume":"26","author":"Hacker","year":"2020","journal-title":"Emerg. Infect. Dis."},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Rees, E.M., Lotto Batista, M., Kama, M., Kucharski, A.J., Lau, C.L., and Lowe, R. (2023). Quantifying the relationship between climatic indicators and leptospirosis incidence in Fiji: A modelling study. PLoS Glob. Public Health, 3.","DOI":"10.1371\/journal.pgph.0002400"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"539","DOI":"10.1016\/S1995-7645(12)60095-9","article-title":"Modeling seasonal leptospirosis transmission and its association with rainfall and temperature in Thailand using time-series and ARIMAX analyses","volume":"5","author":"Chadsuthi","year":"2012","journal-title":"Asian Pac. J. Trop. Med."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"2400611","DOI":"10.2807\/1560-7917.ES.2025.30.15.2400611","article-title":"Increased incidence of human leptospirosis and the effect of temperature and precipitation, the Netherlands, 2005 to 2023","volume":"30","author":"Obels","year":"2025","journal-title":"Eurosurveillance"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"631","DOI":"10.1016\/j.trstmh.2010.07.002","article-title":"Climate change, flooding, urbanisation and leptospirosis: Fuelling the fire?","volume":"104","author":"Lau","year":"2010","journal-title":"Trans. R. Soc. Trop. Med. Hyg."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"1550","DOI":"10.1017\/S0950268815002903","article-title":"Environmental factors and public health policy associated with human and rodent infection by leptospirosis: A land cover-based study in Nan province, Thailand","volume":"144","author":"Tantrakarnapa","year":"2016","journal-title":"Epidemiol. Infect."},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Villanueva-Miranda, I., Xiao, G., and Xie, Y. (2025). Artificial intelligence in early warning systems for infectious disease surveillance: A systematic review. Front. Public Health, 13.","DOI":"10.3389\/fpubh.2025.1609615"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"1865","DOI":"10.3201\/eid3009.240082","article-title":"Use of Open-Source Epidemic Intelligence for Infectious Disease Outbreaks, Ukraine, 2022","volume":"30","author":"Kannan","year":"2024","journal-title":"Emerg. Infect. Dis."}],"container-title":["Pathogens"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2076-0817\/15\/7\/759\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,7,20]],"date-time":"2026-07-20T11:16:28Z","timestamp":1784546188000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2076-0817\/15\/7\/759"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,7,20]]},"references-count":34,"journal-issue":{"issue":"7","published-online":{"date-parts":[[2026,7]]}},"alternative-id":["pathogens15070759"],"URL":"https:\/\/doi.org\/10.3390\/pathogens15070759","relation":{},"ISSN":["2076-0817"],"issn-type":[{"value":"2076-0817","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,7,20]]}}}