Molecular Screening and Characterization of Enteric Protozoan Parasites and Microsporidia in Wild Ducks from Portugal

Enteric parasites pose significant threats to both human and veterinary health, ranking among the top causes of mortality worldwide. Wild migratory waterfowl, such as ducks, may serve as hosts and vectors for these parasites, facilitating their transmission across ecosystems. This study conducted a molecular screening of enteric parasites in three species of wild ducks of the genus <i>Anas</i> (<i>A. acuta</i>, <i>A. platyrhynchos</i> and <i>A. crecca</i>) from Portugal, targeting <i>Blastocystis</i> sp., <i>Balantioides coli</i>, <i>Cryptosporidium</i> spp., <i>Encephalitozoon</i> spp., and <i>Enterocytozoon bieneusi</i>. Fecal samples from 71 ducks were analyzed using PCR and sequencing techniques. The results revealed a 2.82% occurrence of <i>Blastocystis</i> sp. subtype 7 and <i>Cryptosporidium baileyi</i>, marking the first molecular detection of these pathogens in wild ducks in Portugal. While previous studies have documented these parasites in <i>Anas</i> spp. in other regions, this study contributes novel data specific to the Portuguese context. No evidence of <i>Balantioides coli</i>, <i>Encephalitozoon</i> spp. or <i>Enterocytozoon bieneusi</i> was found. These findings highlight the potential role of migratory ducks as vectors for zoonotic protozoa, emphasizing the need for enhanced surveillance of avian populations to mitigate cross-species transmission risks. Further research is warranted to understand the global public health implications associated with migratory waterfowl.