Evaluations of hydrologic risk factors for canine leptospirosis: 94 cases (2002-2009).

Hydrologic and soil-hydrologic variables were evaluated retrospectively as potential risk factors for canine leptospirosis in Kansas and Nebraska using Geographic Information Systems (GIS). The sample included 94 positive and 185 negative dogs for leptospirosis predominantly based on PCR test for leptospires in urine. Hydrologic variables for the region were derived from National Hydrographic Dataset, National Flood Hazard Layer, National Wetlands Inventory; and soil-hydrologic variables from Soil Survey Geographic Database around geocoded addresses of case/control locations. Multivariable logistic models were used to determine association between hydrologic and soil-hydrologic variables and test status. Distance from water features (OR=0.82; 95% CI=0.79, 0.86), hydrologic density (OR=2.80; 95% CI=1.58, 4.96) and frequently flooded areas (OR=4.05; 95% CI=2.17, 7.55) within 2500 m surrounding case/control locations were significant risk factors for canine leptospirosis. Vaccination for dogs that live closer to water features, landscapes dominated by water features and frequent floods should be considered for leptospirosis prevention.

Neighborhood-level socioeconomic and urban land use risk factors of canine leptospirosis: 94 cases (2002-2009).

Associations of housing, population, and agriculture census variables, and presence near public places were retrospectively evaluated as potential risk factors for canine leptospirosis using Geographic Information Systems (GIS). The sample population included 94 dogs positive for leptospirosis based on a positive polymerase chain reaction test for leptospires on urine, isolation of leptospires on urine culture, a single reciprocal serum titer of 12,800 or greater, or a four-fold rise in reciprocal serum titers over a 2-4 week period; and 185 dogs negative for leptospirosis based on a negative polymerase chain reaction test and reciprocal serum titers less than 400. Multivariable logistic regressions revealed different risk factors among different census units; however, houses lacking complete plumbing facilities [OR=2.80, 95% C.I.=1.82, 4.32 (census unit, block group); OR=1.36, 95% C.I.=1.28, 1.45 (census tract); OR=3.02, 95% C.I.=2.60, 3.52 (county)]; and poverty status by age (18-64) [OR=2.04, 95% C.I.=1.74, 2.39 (block group); OR=1.53, 95% C.I.=1.41, 1.67 (census tract); and OR=1.62, 95% C.I.=1.50, 1.76 (county)] were consistent risk factors for all census units. Living within 2500 m of a university/college and parks/forests were also significantly associated with leptospirosis status in dogs. Dogs that live under these circumstances are at higher risk for leptospirosis and pet owners should consider vaccination.