Reconsidering the risks of Linguatula in Australia: A review of an overlooked introduced parasite.

Abstract

Linguatula serrata is a globally distributed zoonotic parasite that remains largely overlooked in public health. Although traditionally described as having an indirect life cycle involving carnivorous definitive hosts and herbivorous intermediate hosts, emerging evidence suggests greater complexity in transmission pathways and host associations, with some observations raising the possibility of a direct life cycle. In Australia, L. serrata, likely introduced through domestic animals and livestock during colonisation, is now well established across both introduced and native hosts, indicating sustained transmission at the wildlife-livestock-human interface, although human infection has not been reported. Recognised transmission pathways, via ingestion of eggs from environmental contamination or infective nymphs in raw or undercooked offal, are plausible in Australia. This Perspective synthesises current knowledge of its biology, transmission, and host range, and highlights its role as both a foodborne and environmentally transmitted zoonosis. We argue that the absence of reported human cases likely reflects under-recognition due to non-specific clinical presentation, diagnostic limitations, and limited awareness among health professionals. Together, these observations suggest that L. serrata may be more epidemiologically relevant in Australia than currently recognised and should be reconsidered within Australia's One Health and zoonotic disease frameworks.