肠道菌群作为宿主健康的重要调节因子，其在寄生原虫感染过程中的作用受到广泛关注。多种寄生原虫可通过直接侵袭肠道上皮、激活炎症反应、破坏肠屏障或改变代谢通路诱导宿主肠道菌群失调，具体表现为有益菌减少、致病菌增殖及菌群多样性下降。刚地弓形虫和蓝氏贾第鞭毛虫可引发菌群重构并持续影响宿主代谢，利什曼原虫和锥虫在其传播媒介肠道内的发育过程受微生物群显著影响，媒介共生菌可对病原体的生长与分化发挥促进或抑制作用。肠道菌群不仅影响寄生虫定植和感染程度，还可通过其代谢产物（如短链脂肪酸、吲哚类、胆汁酸）调节宿主免疫应答，成为寄生虫感染过程中不可忽视的关键调节因子。本文对重要寄生原虫感染引起的肠道菌群改变及其潜在的作用机制进行综述，旨在为深入理解其致病过程及微生态干预策略的开发提供参考。

Gut microbiota, as a crucial regulator of host health, has received growing attention for its role in parasitic protozoan infections. A variety of parasitic protozoa may induce host gut microbiota dysbiosis through direct invasion of intestinal epithelium, activation of inflammatory responses, disruption of intestinal barriers, or alterations in metabolic pathways, and this dysbiosis is characterized by a decrease in beneficial bacteria, proliferation of pathogenic bacteria, and a reduction in microbial diversity. Toxoplasma gondii and Giardia lamblia have been found to induce microbiota remodeling and persistently affect host metabolism, while the development of Leishmania and Trypanosoma in the intestines of their transmitting vectors are remarkably affected by microbiota. In addition, symbiotic bacteria may promote or inhibit pathogen growth and differentiation. Gut microbiota not only affects parasite colonization and infection severity but also modulates host immune responses through metabolites such as short-chain fatty acids, indoles, and bile acids, which is a non-negligible key regulator during parasitic infections. This review summarizes the alterations in gut microbiota caused by major parasitic protozoan infections and their potential mechanisms of actions, so as to provide insights into better understanding of pathogenesis and development of microecological intervention strategies.