Update on Blastocystis: highlights from the Fourth International Blastocystis Conference

<ns3:p>While the stramenopile <ns3:italic>Blastocystis</ns3:italic>, first discovered in 1911, is considered the most prevalent enteric protist in humans, its biology remains largely unexplored. Clinical studies have only recently begun investigating the role of <ns3:italic>Blastocystis</ns3:italic> in the gut and its relationship with the gut microbiome, and whether it plays a pathogenic role in human and animal health. Aiming to gather leading researchers in the field to encourage and stimulate cross-disciplinary dialogue while fostering long-term international collaborations, the Fourth International <ns3:italic>Blastocystis</ns3:italic> Conference was hosted from the 17<ns3:sup>th</ns3:sup> to the 19<ns3:sup>th</ns3:sup> of September 2024 in Heraklion (Crete, Greece). The event was mainly supported by the COST Action CA21105, “<ns3:italic>Blastocystis</ns3:italic> under One Health”, and the Microbiology Society. The multi- and interdisciplinary conference programme covered all aspects related to <ns3:italic>Blastocystis</ns3:italic> evolutionary biology and advances in omics, intestinal ecology (gut microbiome), clinical significance and association with disease, diagnosis and molecular characterisation, as well as epidemiology and One Health. The high-quality presentations discussed at the conference provided researchers with a synthesis of recent advancements, while key research questions, knowledge gaps, and future steps in <ns3:italic>Blastocystis</ns3:italic> research were identified. Herein, we aim to provide a thorough overview of the presentations at the conference. The COST Action CA21105, <ns3:italic>“Blastocystis</ns3:italic> under One Health”, will build on the insights and collaborations fostered during the conference, promoting integrative research approaches, advancing our understanding of <ns3:italic>Blastocystis</ns3:italic>, and driving future efforts to translate these findings into improved public health strategies.</ns3:p>