title: Historical distribution and host-vector diversity of Francisella tularensis, the causative agent of tularemia, in Ukraine.
abstract: BACKGROUND
  Francisella tularensis, the causative agent of tularemia, is a zoonotic agent that remains across much of the northern hemisphere, where it exists in enzootic cycles. In Ukraine, tularemia has a long history that suggests a need for sustained surveillance in natural foci. To better characterize the host-vector diversity and spatial distribution of tularemia, we analyzed historical data from field collections carried out from 1941 to 2008.
  
  
  RESULTS
  We analyzed the spatial-temporal distribution of bacterial isolates collected from field samples. Isolates were characterized by source and dominant land cover type. To identify environmental persistence and spatial variation in the source of isolation, we used the space-time permutation and multinomial models in SaTScan. A total of 3,086 positive isolates were taken from 1,084 geographic locations. Isolation of F. tularensis was more frequent among arthropods [n = 2,045 (66.3%)] followed by mammals [n = 619 (20.1%)], water [n = 393 (12.7%)], and farm produce [n = 29 (0.94%)], respectively. Four areas of persistent bacterial isolation were identified. Water and farm produce as sources of bacterial isolation were clustered.
  
  
  CONCLUSIONS
  Our findings confirm the presence of long-standing natural foci of F. tularensis in Ukraine. Given the history of tularemia as well as its environmental persistence there exists a possibility of (re)emergence in human populations. Heterogeneity in the distribution of tularemia isolate recovery related to land cover type supports the theory of natural nidality and clusters identify areas to target potential sources of the pathogen and improve surveillance.
authors.affiliation: Department of Geography, Spatial Epidemiology & Ecology Research Laboratory, University of Florida, Gainesville, FL, USA. jhightower@ufl.edu.
authors.forename: Jake
authors.initials: J
authors.lastname: Hightower
authors.affiliation: Department of Geography, Spatial Epidemiology & Ecology Research Laboratory, University of Florida, Gainesville, FL, USA. itk@ufl.edu.|Emerging Pathogens Institute, University of Florida, Gainesville, FL, USA. itk@ufl.edu.
authors.forename: Ian T
authors.initials: IT
authors.lastname: Kracalik
authors.affiliation: Central Sanitary Epidemiological Station, Kyiv, Ukraine. vydaykon@ukr.net.
authors.forename: Nataliya
authors.initials: N
authors.lastname: Vydayko
authors.affiliation: Department of Geography, Kansas State University, Manhattan, KS, USA. dgoodin@k-state.edu.
authors.forename: Douglas
authors.initials: D
authors.lastname: Goodin
authors.affiliation: Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA. ggurrigl@jhsph.edu.
authors.forename: Gregory
authors.initials: G
authors.lastname: Glass
authors.affiliation: Department of Geography, Spatial Epidemiology & Ecology Research Laboratory, University of Florida, Gainesville, FL, USA. jkblackburn@ufl.edu.|Emerging Pathogens Institute, University of Florida, Gainesville, FL, USA. jkblackburn@ufl.edu.
authors.forename: Jason K
authors.initials: JK
authors.lastname: Blackburn
mesh_terms: D000818:Animals; D004197:Disease Reservoirs; D005604:Francisella tularensis / Q000502:physiology*; D012377:Rodentia; D013045:Species Specificity; D014406:Tularemia / Q000453:epidemiology / Q000382:microbiology*; D014455:Ukraine / Q000453:epidemiology; D015047:Zoonoses