The aim of this systematic review was to identify articles on prevalence of leptospirosis in stray and sheltered dogs worldwide and access the methodological quality of the recovered papers. Six databases (CABI, Cochrane, Pubmed, Scielo, Scopus and Web of Science) were searched, without restriction on year or location where the studies were performed. The search recovered 476 articles and 60 were selected for analysis according to quality criteria. None of the selected articles showed a complete explanation for the sample size adopted (probabilistic sampling), leading to the impossibility of recalculation of leptospirosis prevalence for stray or sheltered dogs. Among the analyzed papers 43.33% (26/60) showed five of the ten quality criteria analyzed, 16.67% (10/60) three, 15.00% (9/60) four, 10.00% (6/60) six, 6.67% (4/60) eight, only 5.00% (3/60) showed nine of the ten criteria analyzed, whereas two papers showed two [1.67% (1/60)] and seven [1.67% (1/60)] of the ten criteria assessed. The majority of the papers were published in the Americas [45.00% (27/60)] and in the last sixteen years (2003 to 2019) [81.67% (49/60)], and most of the sampled dogs were stray dogs [65.00% (39/60)]. The leptospirosis diagnostic test used more frequently was Micro Agglutination Test (MAT) [78.33% (47/60)] followed by polymerase Chain Reaction (PCR) [23.33% (14/60)], whereas the most common serovars identified were Canicola [71.43% (35/49)], Icterohaemohrragiae [65.31% (32/49)], Grippotyphosa [40.82% (20/49)] and Pomona [40.82% (20/49)]. In conclusion, our results showed that Leptospira spp. is present in stray and sheltered dogs worldwide, but the complete comprehension of the prevalence of leptospirosis in these populations could not be achieved due to the low methodologic quality of the recovered studies about leptospirosis in stray and sheltered dogs.

Leptospirosis has been widely reported in insular environments worldwide, characterizing a major public health threat. Although low genetic biodiversity is expected in these regions, the introduction of domestic and synanthropic mammals may contribute to the wider diversity leptospiral strains in insular settings. This study proposes a large-scale investigation of Leptospira infection in animals from Fernando de Noronha archipelago, Brazil. A total of 1,265 blood samples from domestic (n=682), synanthropic (n=133) and wild (n=450) animals were collected between 2007 and 2014, totaling 12 species. The presence of anti-Leptospira spp. antibodies was investigated by the Microscopic Agglutination Test (MAT) and kidney samples from synanthropic rodents were collected for the isolation of Leptospira spp. The leptospires recovered were further characterized by MAT with polyclonal antibodies, whole genome sequencing and Multilocus Sequence Typing (MLST). The MAT results revealed the presence of agglutinins in 90 samples (7.1%), and the most frequently found serogroup was Icterohaemorrhagiae (n=57) in practically all species included. Viable leptospires were recovered from one brown rat, and characterization revealed that the isolate belongs to L. interrogans serogroup Pyrogenes. This study stands as the most comprehensive investigation of Leptospira spp. infection in Fernando de Noronha archipelago, also providing the characterization of the first leptospiral strain ever isolated from an insular setting in Brazil. The results suggest that synanthropic rodents play a major role in the transmission of leptospirosis among wildlife and domestic species in the archipelago.