RESUMEN
Leptospirosis, caused by pathogenic spirochetes of the genus Leptospira spp., is a globally significant zoonotic disease that affects humans and animals. In cattle, leptospirosis is associated not only with overt clinical manifestations but also with reproductive diseases, including infertility. This study assesses the potential correlation between leptospirosis and infertility in Uruguayan beef cattle. A case-control study involved 31 beef herds with no prior history of Leptospira vaccination. In each herd, veterinarians identified 10 non-pregnant (cases) and 25 pregnant cows (controls) using ultrasound, and blood and urine samples were collected from each cow. Serological diagnosis was performed using the Microscopic Agglutination Test (MAT), and quantitative PCR (qPCR) was used to assess Leptospira excretion. Additionally, antibodies against bovine viral diarrhea virus (BVDV) and infectious bovine rhinotracheitis (IBR) were tested. The results demonstrated an association between seropositivity to the Sejroe serogroup (cut-off 1:200) and infertility in cattle (OR=1.31; p-value=0.06). Furthermore, the level of Leptospira excretion (qPCR) in urine was associated with increased infertility risk, with cows excreting over 100 copies per mL of urine having the highest odds of infertility (OR=2.34; p-value<0.01). This study suggests a potential association between leptospirosis and infertility in Uruguayan beef cattle, emphasizing the importance of both serological and molecular diagnostics for assessing reproductive health in cattle herds. Future research should explore the impact of Leptospira serogroups on other reproductive disorders in cattle.