Blastocystis in free-ranging wild ruminant species across the Iberian Peninsula

Authors: FIGUEIREDO, ANA - University Of Aveiro (UA); DASHTI, ALEJANDRO - National Center For Microbiology, The Institute Of Health Carlos Iii; Maloney, Jenny; Molokin, Aleksey; George, Nadja; KOSTER, PAMELA - National Center For Microbiology, The Institute Of Health Carlos Iii; BAILO, BEGONA - National Center For Microbiology, The Institute Of Health Carlos Iii; SANCHEZ DE LAS MATAS, ANA - National Center For Microbiology, The Institute Of Health Carlos Iii; HABELA, MIGUEL - University Of Extremadura; RIVERO-JUAREZ, ANTONIO - Universidad De Cordoba; VICENTE, JOAQUIN - Collaborator; SERRANO, EMMANUEL - Autonomous University Of Barcelona; ARNAL, MARIA - University Of Zaragoza; FERNANDEZ DE LUCO, DANIEL - University Of Zaragoza; MORRONDO, PATROCINIO - University Of Santiago De Compostela; ARMENTEROS, JOSE - Universidad De Murcia; BALSEIRO, ANA - University Of Leon; CARDONA, GUILLERMO - Collaborator; MARTINEZ-CARRASCO, CARLOS - Universidad De Murcia; TORRES, RITA - University Of Aveiro (UA); FONSECA, CARLOS - University Of Aveiro (UA); MYSTERUD, ATLE - University Of Oslo; CARVALHO, JOA - University Of Aveiro (UA); CALERO-BERNAL, RAFAEL - Complutense University Of Madrid (UCM); GONZALEZ-BARRIO, DAVID - National Center For Microbiology, The Institute Of Health Carlos Iii; Santin, Monica; CARMENA, DAVID - National Center For Microbiology, The Institute Of Health Carlos Iii

Submitted to: Veterinary Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/19/2025
Publication Date: 7/9/2025
Citation: Figueiredo, A.M., Dashti, A., Maloney, J.G., Molokin, A., George, N.S., Koster, P.C., Bailo, B., Sanchez De Las Matas, A., Habela, M.A., Rivero-Juarez, A., Vicente, J., Serrano, E., Arnal, M.C., Fernandez De Luco, D., Morrondo, P., Armenteros, J.A., Balseiro, A., Cardona, G.A., Martinez-Carrasco, C., Torres, R.T., Fonseca, C., Mysterud, A., Carvalho, J., Calero-Bernal, R., Gonzalez-Barrio, D., Santin, M., Carmena, D. 2025. Blastocystis in free-ranging wild ruminant species across the Iberian Peninsula. Veterinary Research. 56. Article e145. https://doi.org/10.1186/s13567-025-01563-3.
DOI: https://doi.org/10.1186/s13567-025-01563-3

Interpretive Summary: The increase in wild animal populations is contributing to the spread of infectious diseases. Blastocystis is a common parasite that can cause gastrointestinal illnesses in humans and animals worldwide. However, the role of wildlife in the epidemiology of Blastocystis is poorly understood. To fill this gap, fecal samples from wild animals across Spain and Portugal were collected and examined to detect the presence of Blastocystis using molecular techniques. Blastocystis was found in 13.8% of the wild animals analyzed. The study identified fifteen Blastocystis subtypes, including novel subtype (named ST49), with over half of the positive samples containing multiple subtypes. Our results enhance our understanding of Blastocystis diversity and host preference present in wild animals, which will assist in clarifying the relationships between the wild and domestic cycles of this parasite and may ultimately provide tools to help manage future public health and epidemiological scenarios. This information is useful for scientists, veterinarians, and public health agencies to better understand how Blastocystis spreads.

Technical Abstract: The rise of wild ungulate populations across Europe represents an increasingly important source for the spread of infectious diseases, particularly potentially zoonotic pathogens. Blastocystis is one of the most common intestinal parasites observed in humans and animals worldwide. Studies on Blastocystis occurrence and subtype (ST) diversity in free-ranging wild ruminants are lacking globally, and more data are needed to understand the epidemiological scenario in wild European ruminants. To fill this gap, we collected 833 faecal samples from free-ranging wild ungulates across Spain (n = 699) and Portugal (n = 134) between 1998 and 2021. Using conventional PCR and next-generation amplicon sequencing (NGS), Blastocystis was found in 13.8% (115/833; 95% CI: 11.5–16.3) of the wild ruminants analysed, and its occurrence was significantly higher in Portugal (38.1%, 51/134; 95% CI: 29.8–46.8) than in Spain (9.2%, 64/699; 95% CI: 7.1–11.5). Fifteen Blastocystis STs, fourteen previously recognized (ST2, ST5, ST10, ST13, ST14, ST21, ST23-ST26, ST30, and ST42-ST44) and one novel (ST49), were detected among the surveyed wild ruminant populations. Novel ST49 was described using Oxford Nanopore sequencing to produce full-length reference sequences of the small subunit ribosomal subunit rRNA gene. A greater ST diversity was observed in Spanish samples, possibly due to the larger diversity of host species sampled. Mixed infections were found in over half of the total Blastocystis-positive samples (58.3%, 67/115). Our results have enhanced the knowledge regarding Blastocystis occurrence and ST diversity and host preference present in wild ruminants from the Iberian Peninsula, which will assist in clarifying the relationships between the sylvatic and domestic cycles of this parasite and may ultimately provide tools to help manage future public health epidemiological scenarios.