Molecular epidemiological surveillance of circovirus in avian and mammalian species on the Brazilian coast.

Circoviruses (CVs) infect diverse mammals, birds, and freshwater fish and are linked to diseases causing major economic losses. Despite being well studied in psittacines, their circulation in other avian groups and mammals is poorly understood. We conducted molecular surveillance of CVs in migratory birds and mammals along the Paraná coast, southern Brazil. Sterna hirundinacea specimen tested positive by Nested-PCR for GullCV. In the GullCV-infected bird, histopathology revealed nonspecific lesions, including marked splenic lymphoid atrophy, cachexia-related changes, acute tubular necrosis, and generalized congestion. Sanger sequencing revealed 83% nucleotide identity with CV sequences previously reported in gulls from the United States, which was consistent with results obtained by NGS and Rep-based phylogenetic analysis. These findings contribute to the understanding of CV diversity, distribution, and host range.