Infection with tongue worms in Australian animals

We present our findings on the prevalence, distribution, histopathology and specific identification of an intriguing parasite, the tongue “worm” in Australia. The tongue-worm, Linguatula serrata (Pentastomida: Linguatulidae) is an obligate arthropod parasite that may be found in the nostrils of carnivores. Larval stages of the parasite inhabit the lymph nodes, liver and lungs of their intermediate hosts, including various species of livestock and wildlife. Tongue worms are of zoonotic significance, human infection with both adult and larval stages of the parasite having been reported in several countries. In Australia there have been few reports of tongue worms, generally as an accidental finding. In this study we examined wild canids, vulpids and lapids as well as domestic livestock in South-Eastern Australia for infection with these parasites. A combined morphological and molecular approach was used for their specific identification. The prevalence of these parasites in the region was unexpectedly high, with 67% of the wild dogs examined affected. Histopathological examination of the host tissues revealed mechanical damage to the mucosal membranes in the nasal cavity and moderately severe granulomatous lymphadenitis with some intra-lesional parasitic remnants in damaged lymph nodes. Currently tongue worm infection and the human and animal disease impacts arising from infection are not of primary concern to Australian veterinarians and health practitioners. Wildlife is now recognised globally as an important source of emerging human pathogens. The prevalence of these zoonotic parasites in Australian carnivores indicates the importance of increasing public awareness of these zoonotic parasites, particularly health professionals and veterinarian.