Listeria ivanovii-an underestimated pathogen in veterinary medicine

Listeria (L.) ivanovii is a Gram-positive, facultatively intracellular rod-shaped bacterium. It is predominantly associated with animal infections, particularly in ruminants. Unlike L. monocytogenes, which is widely recognised as a major zoonotic and foodborne pathogen, L. ivanovii is often overlooked, despite documented cases of abortion, stillbirth, and neonatal septicemia in sheep, goats, and cattle. This review provides an overview of L. ivanovii taxonomy, microbiological characteristics, virulence determinants, host adaptation, epidemiology, transmission routes, diagnostic challenges, antimicrobial susceptibility, and preventive measures in animal husbandry. Available evidence suggests that infections with L. ivanovii tend to be sporadic, with occasional outbreaks of abortions in small ruminant flocks. Large-scale epizootics and sustained interregional spread have not been documented. Human infections are rare and predominantly occur in immunocompromised individuals, which supports the assumption that the zoonotic potential is limited under normal conditions. Underdiagnosing and missing awareness likely contribute to the perception of rarity, as routine laboratory workflows often do not differentiate Listeria species beyond the genus level. The increasing use of molecular confirmation and whole-genome sequencing may improve species-level detection and clarify epidemiological patterns. Overall, L. ivanovii should be regarded as a specialised pathogen predominantly associated with ruminants and of veterinary relevance. Improved diagnostics and integration into existing surveillance frameworks could enhance our understanding of its true epidemiological role and prevent it from being endemic.