Molecular Detection of Enteric Protozoa in Cattle from North Portugal.

A total of 100 fecal samples collected from cattle in the district of Viana do Castelo, northern Portugal, were molecularly screened for Cryptosporidium spp., Giardia duodenalis, and Blastocystis sp. This study represents the first molecular survey of enteric protozoa in cattle from the district of Viana do Castelo, northern Portugal. Blastocystis sp. was the most frequently detected protozoan and exhibited considerable subtype diversity, including the zoonotic subtype ST3 and the potentially zoonotic subtypes ST10a and ST14, a circumstance highlighting the occurrence in cattle of Blastocystis subtypes with potential public health relevance and the need to further investigate their cross-host transmission dynamics. Giardia duodenalis was detected at a relatively low occurrence, although unsuccessful multilocus sequence typing (MLST) amplification prevented assessment of its assemblages and zoonotic potential. Cryptosporidium spp. were not detected, likely reflecting the predominance of adult cattle in the sampled population. Overall, these findings contribute to the understanding of the molecular epidemiology of enteric protozoa in Portuguese cattle and provide updated baseline geographical data for northern Portugal. Continued molecular surveillance using optimized genotyping approaches and larger, more representative sample sets will be essential to better characterize the diversity, epidemiology, and zoonotic importance of these parasites within a One Health framework.