Immune mechanisms underlying endothelial and placental dysfunction in leptospirosis during pregnancy

Leptospirosis is a zoonotic disease caused by pathogenic bacteria of the genus Leptospira and represents a major public health concern worldwide. Although its systemic manifestations are well documented, the consequences of leptospirosis for reproduction and pregnancy, particularly in humans, remain poorly understood. This narrative review summarizes the principal reproductive outcomes associated with leptospirosis and examines the mechanisms that may contribute to pregnancy complications. In livestock, leptospirosis is a well-established cause of reproductive failure, including abortion and infertility, and is frequently associated with persistent infection and colonization of the genital tract. In humans, where available evidence remains limited, adverse pregnancy outcomes may be mediated predominantly by systemic endothelial injury, inflammatory activation, and immune dysregulation leading to impaired placental perfusion, rather than solely by direct infection of placental tissues. We therefore integrate evidence from veterinary research and human studies to examine the biological mechanisms through which leptospirosis may contribute to pregnancy complications and potentially overlap with other pregnancy-related disorders. A One Health approach that combines human, animal, and environmental data is essential to improve disease prevention, reduce its reproductive burden, and protect the health of pregnant individuals and their developing fetuses.