Prevalence and Molecular Characterization of Cryptosporidium in Diarrheic Dairy Calves: A Descriptive Study in Family Farms of Southern Santa Catarina, Brazil

This study describes the management practices and evaluates the molecular identification of Cryptosporidium species in dairy calves from southern Santa Catarina, Brazil, an important dairy cattle milk production region. Fecal diarrhea samples from 67 calves aged 1 to 90 days across 22 farms were analyzed by nested PCR for Cryptosporidium DNA detection. Sequencing 24 PCR-positive samples from 14 farms revealed the presence of Cryptosporidium parvum, demonstrating the circulation of the species in the farms. Phylogenetic analysis confirmed high sequence similarity (99.01–100%) with reference strains, indicating genetic diversity and homogeneity in infection dynamics. The identification of C. parvum, a zoonotic species, raises significant concerns for animal and public health. This research represents molecular evidence of the Cryptosporidium parvum in diarrheic dairy calves from farms in the southern part of Santa Catarina, Brazil, underscoring the need for targeted control strategies and ongoing molecular surveillance to mitigate transmission risks in dairy farming systems.