Evaluation of environmental risk factors for leptospirosis in dogs: 36 cases (1997-2002).
OBJECTIVE
To identify environmental risk factors for leptospirosis.


METHODS
Retrospective study.


METHODS
36 dogs with leptospirosis and 138 dogs seronegative for leptospirosis as determined by microscopic agglutination test for antibodies against Leptospira spp.


METHODS
Medical records of dogs evaluated for leptospirosis from 1997 though 2002 were identified. Owner address was used to geocode locations of dogs, and location-specific environmental risk factor data were obtained by use of a geographic information system. Risk of leptospirosis was estimated by odds ratios, controlling for potential confounding by dog age, sex, and breed.


RESULTS
Leptospirosis in 19 of the 30 dogs in which an infecting Leptospira serovar could be identified was associated with Leptospira kirschneri serovar grippotyphosa infection. Dogs in which a diagnosis of leptospirosis was made, and dogs with leptospirosis caused by L kirschneri serovar grippotyphosa, were more likely to have addresses located in areas classified as rural in 1990 but urban in 2000. By use of information on recent urbanization and a logistic regression model, the status of 81.6% and 89.8% of dogs with leptospirosis and leptospirosis caused by serovar grippotyphosa, respectively, were correctly classified. Other environmental variables (proximity to streams, recreational areas, farmland, wetlands, areas subject to flooding, and areas with poor drainage; annual rainfall; and county cattle or pig population) did not significantly improve accuracy of classification.


CONCLUSIONS
Dogs in periurban areas are at greater risk of leptospirosis. Vaccination of dogs in these areas to protect against leptospirosis should be considered.
Ward
Michael P
MP
Department of Veterinary Pathobiology, School of Veterinary Medicine, Purdue University, West Lafayette, IN 47907-2027, USA.
Guptill
Lynn F
LF
Wu
Ching Ching
CC
D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood*; D004283:Dog Diseases / Q000097:blood / Q000453:epidemiology*; D004285:Dogs; D004783:Environmental Microbiology; D005260:Female; D040362:Geographic Information Systems; D007919:Leptospira / Q000276:immunology / Q000302:isolation & purification; D007922:Leptospirosis / Q000097:blood / Q000453:epidemiology / Q000662:veterinary*; D016015:Logistic Models; D008297:Male; D016017:Odds Ratio; D012189:Retrospective Studies; D012307:Risk Factors; D016036:Seroepidemiologic Studies; D014507:Urbanization; D014611:Vaccination / Q000662:veterinary
D000907:Antibodies, Bacterial