Fetal and neonatal demise in zoonotic diseases: pathology and pathogenesis

Zoonotic infections constitute a major cause of reproductive failure and perinatal mortality in humans and animals. Among the most relevant etiological agents are Listeria monocytogenes, Brucella spp., and Toxoplasma gondii, which, despite distinct biological properties, share the capacity to breach placental defenses, establish intracellular niches, and impair fetal development. This review aims to synthesize current knowledge on the pathological and pathogenic mechanisms underlying fetal and neonatal death associated with these pathogens, with a focus on placental infection, vertical transmission, and tissue injury. The outcome of infection is highly dependent on the gestational stage at exposure: early gestational infection is frequently associated with embryonic loss or resorption, whereas infection in later stages more commonly results in abortion, stillbirth, or congenital disease. Elucidation of these mechanisms is essential for the development of targeted preventive and control strategies for zoonotic reproductive diseases.