Fernando de Noronha Island is located 360 km far from Recife and Natal, capitals of the states of Pernambuco and Rio Grande do Norte, Brazil, respectively. It has an area of approximately 18.4 km2 and constitutes the submerged part of a volcanic edifice currently inactive, which base rests 4,000 m deep in the Atlantic Ocean. Blood samples were collected from all the cattle raised in the Island (n = 88), 200 feral cats and 150 rodents, and the sera were screened by MAT (Serogroups Australis; Autumnalis; Ballum; Bataviae; Canicola; Cynopteri; Djasiman; Grippotyphosa; Hebdomadis; Icterohaemorrhagiae; Icterohaemorrhagiae; Panama; Pomona; Pyrogenes; Sejroe e Tarassovi) for detection of anti-Leptospira spp. antibodies. Initially all sera were screened at 1100 dilution and those with 50% or more agglutination were titrated at two-fold geometric dilutions. The serum titer was defined as the reciprocal of the highest positive dilution.[...](AU)