title: A cross sectional observational study to estimate herd level risk factors for Leptospira spp. serovars in small holder dairy cattle farms in southern Chile.
abstract: BACKGROUND
  The south of Chile constitutes the main cattle milk producing area of the country. Regarding leptospirosis control in Chile, there is neither an official program nor an epidemiological characterization of smallholder dairy farms. This study was carried out to determine Leptospira seroprevalence and to evaluate risk factors associated with seropositivity at herd level in smallholder bovine dairy herds in southern Chile.A cross-sectional study was conducted, and a convenient sample of 1,537 apparently healthy dairy cows was included in the study. Individual blood samples were taken and examined for six selected reference Leptospira serovars by the Microscopic Agglutination Test (MAT).
  
  
  RESULTS
  Of the included herds 75% (52/69) showed serological titers against one or more Leptospira serovar. Leptospira borgpetersenii serovar Hardjo was the serovar most frequently (81%) reported from animals with positive results. The variables considered risk factors for Leptospira seropositivity were calve natural breeding system, using a specific calving area and vaccination against Leptospira. Adult cows in contact with calves weaned, proved to be a protective factor against infection.
  
  
  CONCLUSIONS
  Herds neglecting the management practices mentioned in this study could represent an important source of Leptospira infection for other herds in the same geographic area, as well as for other animal species.
authors.affiliation: Department of Biochemistry and Microbiology, Faculty of Sciences, Universidad Austral de Chile, Edificio Instapanel, Campus Isla Teja, CC 567 Valdivia, Chile. miguelsalgado@uach.cl.
authors.forename: Miguel
authors.initials: M
authors.lastname: Salgado
authors.forename: Barbara
authors.initials: B
authors.lastname: Otto
authors.forename: Errol
authors.initials: E
authors.lastname: Sandoval
authors.forename: German
authors.initials: G
authors.lastname: Reinhardt
authors.forename: Sofia
authors.initials: S
authors.lastname: Boqvist
mesh_terms: D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000097:blood / Q000453:epidemiology / Q000382:microbiology*; D002677:Chile / Q000453:epidemiology; D003430:Cross-Sectional Studies; D003612:Dairying; D007919:Leptospira / Q000145:classification*; D007922:Leptospirosis / Q000097:blood / Q000453:epidemiology / Q000662:veterinary*; D012307:Risk Factors; D012698:Serologic Tests