Blastocystis in domestic mammals and poultry: from prevalence patterns to gut physiology

Blastocystis is a common intestinal protist in humans and animals, yet its ecological role and clinical significance remain debated. Companion animals and livestock are of particular interest due to their close contact with humans and potential reservoir roles. This review synthesizes current knowledge on Blastocystis occurrence and diversity in these animal groups, reframing the discussion through the lens of host digestive physiology and microbiome ecology. Rather than a taxonomic inventory, we group animals as carnivores, omnivores, or herbivores to highlight how gastrointestinal physiology and diet might shape colonization. Carnivores show low prevalence, herbivores exhibit high subtype richness, and omnivores display intermediate patterns. Growing evidence links Blastocystis to gut eubiosis, highlighting the need for broader, integrative research across hosts and environments.