First report of Toxoplasma gondii naturally infecting free-living Franciscana Dolphin (Pontoporia blainvillei).

Toxoplasma gondii is a globally distributed protozoan capable of infecting marine animals. This study reports the first isolation of T. gondii in Pontoporia blainvillei (Franciscana dolphin), found post-mortem in Laguna, southern coast of Santa Catarina, Brazil. Necropsy was performed on a juvenile female, and pooled tissue samples (heart, lungs, brain, liver) were digested and bioassayed in mice. All three mice died within 21 days post-inoculation. Serological testing by indirect immunofluorescence assay (IFA) detected antibodies against T. gondii in two mice, with titers of 1:64 and 1:256. Tachyzoites were observed in peritoneal washes and lung imprints, and parasitic cysts were detected in brain tissue. PCR-RFLP analysis identified the ToxoDB genotype #170. This is the first report of genotype #170 in cetaceans, previously found only in alpacas, goats, and free-range chickens in North America. These results emphasize the wide dispersal potential of T. gondii and support the use of cetaceans as sentinels for marine environmental contamination.