Leptospirosis is a worldwide spread zoonotic disease that affects a wide range of mammals, leading not only to clinical acute manifestations, but also to asymptomatic or unnoticed illness. It has been associated with animal contact and handling, particularly companion animals, livestock and sinantropic rodents. The contact with contaminated water collections secondary to sinantropic rodent's proximity is a well described risk factor despite the location, however, dogs can also play an important role in the epidemiology of leptospirosis. The dog is the reservoir for leptospiras from Canicola serogroup, and apparently healthy animals could harbor leptospires into renal structures, promoting urinary shedding of the bacteria and possibly contributing to human and other animal's transmission. To confirm this hypothesis, leptospiral infection of dogs holded in public or private animal shelters will be evaluated. Urine samples will be submitted to real time PCR for genetic material detection and blood samples will be obtained for anti-leptospiral antibodies search (Serum Microscopic Agglutination test). Attempts to isolate leptospires will be done in urine samples obtained by aseptic catheterization or cystocentesis from dogs presenting DNA shedding. To confirm a persistent shedding of leptospires, those animals will be evaluated as to physical conditions, renal biochemical profiles, urinalyses and leptospiruria (real time PCR and attempts to isolate the microorganism) twice a month during three months. For characterization samples of isolates will be submitted to serum agglutination test with anti-leptospires antibodies and MLVA test. Simultaneously, attempts to identifying risk factors for leptospiral infection will be done. Structural and sanitary conditions of the installations, along with others characteristics, gender, age, vaccination status and origin will be evaluated as risk factors of leptospirosis using univariate and multivariate analysis. The identification of dogs with chronic renal shedding of pathogenic leptospires may allow the adoption of sanitary measures and adequate treatment of infected ones.
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