Leptospirosis is an important disease caused by various serovars of Leptospira sp. It can affect humans as well as domestic and wild animals; therefore, it has importance for public health, animal production, and wild species. The aim of this paper is to discuss the epidemiology of animal leptospirosis in Rio de Janeiro, Brazil, as a possible model for other tropical regions. In several studies conducted in the last 20 years, a total of 47 rats, 120 dogs, 875 cows, 695 horses, 1,343 goats, 308 sheep and 351 pigs from all regions of the state, in addition to 107 wild mammals and 73 golden-lion tamarins were tested (MAT) for anti-Leptospira antibodies.

(1) Background: Dogs are known as hosts of Leptospira interrogans and can spread this bacterium to the environment. Although Canicola is responsible for determining chronic disease in dogs, when affected by incidental serogroups such as Icterohaemorrhagiae, acute disease may occur with a predominance of clinical signs with hepatic and renal changes. In endemic areas, it is a serious public health problem. Thus, this study aims to estimate the incidence and duration of elimination of leptospires in the urine of dogs, taking another step from a previous study of our group, by a longitudinal, long-term and molecular approach. (2) Methods: A total of 125 dogs without apparent symptoms of leptospirosis were included in the study. The dogs were all PCR-negative and seronegative at the beginning of the study. Blood samples were collected for hematological examinations and urine for amplification of the lipL32 gene by PCR at five different time points during one year. (3) Results: Out of the 125 dogs, 62 became lipL32 PCR-positive (48.8% (95% CI, 47.9–49.7%)) at some point during the study, distributed as follows: at day 0, all negative; day 90, 18/125 (14.4% (95% CI, 13.5–15.3%)); day 180, 18/125 (14.4% (95% CI, 13.5–15.3%)); day 270, 12/125 (9.6% (95% CI, 8.7–10.5%)); and day 365, 14/125 (11.2% (95% CI, 10.3–12.1%)). Out of the 62 amplicons, 22 were sequenced, targeting a short region of secY gene. Of these, 20 (90.9%) were identical to the L. interrogans serovar Icterohaemorrhagiae, while two (9.1%) were Leptospira noguchii. (4) Conclusions: The fact that the leptospires of the Icterohaemorrhagiae serogroup were characterized was unexpected, since the animals remained clinically asymptomatic during the study. The fact that asymptomatic dogs shed leptospires is not new, but the extent of this fact and the characterized strain is impressive, with an impact on public health that cannot be overlooked.

(1) Background: Vaccination of dogs against leptospirosis is of paramount importance, as they ideally must provide not only long-term protection, but also against the renal carrier state of leptospires. This study assessed the post-vaccine humoral response against Leptospira in naturally exposed dogs and effects on renal carrier status. (2) Methods: A total of 118 dogs were studied for 365 days, separated into Group A (vaccinated, n = 94) and Group B (non-vaccinated, n = 24). Group A was subdivided into three groups: A1 with 32 dogs immunized with the vaccine #1; A2 by 32 dogs with #2; and A3 30 dogs with #3. Serology (MAT and IgG-ELISA) and urinary PCR were conducted. (3) Results: Seroreactivity increased at D15 post-vaccination and, regardless of vaccine brand, remained high up to D180, with antibody switch to IgG after D30. A total of 46.8% of animals from Group A were PCR-positive at least once, in contrast to 75% in Group B, regardless of vaccine brand (p < 0.05; OR: 0.3). (4) Conclusions: All commercial vaccines succeeded at eliciting a long-term IgG-based response and were partially effective at protecting against kidney infection.

(1) Background: Leptospirosis, mainly determined by strains belonging to serogroup Sejroe, has a direct impact on the reproductive efficiency of ruminants, such as sheep. In Brazil, Leptospira santarosai serovar Guaricura, known to be able to chronically colonize the uterine environment, is of special note. Although vaccination minimizes the effects of acute disease, whether or not it can protect from renal colonization remains controversial, and its effects on the genital tract are unknown. In this context, the present study aims to investigate the efficacy of vaccination in the prevention of experimental genital leptospirosis. (2) Methods: Eighteen sheep were divided into three groups: one vaccinated with a polyvalent commercial bacterin, one vaccinated with an autologous bacterin, and one unvaccinated. After 14 days, the sheep were experimentally challenged with 10⁸ leptospires (L. santarosai, serogroup Sejroe, serovar Guaricura, strain FV52) intraperitoneally. Serology and colonization of the urinary and genital tracts were carried out monthly by PCR for 210 days in all animals. (3) Results: Vaccination significantly elicited antibody titers with a predominance of agglutinins against serogroup Sejroe. Both urinary and genital infections were confirmed by PCR. Positivity in urine PCR was absent after D120, while genital infection persisted until the end of the study. Serological results and the finding that vaccination did not avoid renal colonization align with previous studies. Despite vaccination, Leptospira established chronic and asymptomatic colonization of the genital tract until D210, an outstanding finding that remains to be fully understood in its mechanisms. (4) Conclusions: This is the first study conducted to analyze the effects of vaccination in the prevention of genital leptospirosis.