Characterization of the Tongue Worm, Linguatula serrata (Pentastomida), Identified from Hares (Lepus europaeus) in Romania

Linguatula serrata (Frölich, 1789) is a widespread parasite known as the tongue worm belonging to the family Linguatulidae. The adult form of the parasite is usually located in the upper respiratory tract of domestic and wild carnivores while the larval forms are located in the visceral organs of intermediate hosts (various herbivorous mammals). Twenty-four European brown hares (Lepus europaeus) were examined in this study, of which two were positive with L. serrata nymphs. The collected nymphs were examined morphologically using electron-microscopic analysis and molecularly by amplification of 18S rRNA and COX1 genes. Lung tissue samples were also collected and histopathological examination was performed. Histopathological examination revealed the following lesions: generalized inflammatory oedema, granulomas with necrosis, calcification and fibrosis in the bronchial tree. The results of molecular sequencing for L. serrata specimens collected from the European brown hares are deposited in GenBank. This study presents the first report on Linguatula serrata nymphs collected from L. europaeus in Romania, using molecular and morphological characterization simultaneously.

Are feral goats intermediate hosts for Linguatula (Pentastomida) in Australia?

Feral goats, Capra hircus (Bovidae), currently occur across 28% of Australia, and are found in all states and territories as well as some offshore islands. Feral goats are harvested for live export or processed as game meat, with feral goats making up approximately 90% of goats sent to slaughter in Australia. Nymphs of the pentastomid parasite, Linguatula serrata, are common parasites of goats elsewhere in the world, where they cause Halzoun or Marrara disease in humans through the consumption of nymphs in raw or semi-cooked edible offal. Despite being commonly encountered in cattle at slaughter in Australia, L. serrata nymphs have never been reported from feral goats in Australia. Goats at slaughter, however, commonly show infections of lymph nodes, the majority of which are diagnosed as caseous lymphadenitis caused by bacteria, although a small number have no known aetiology. Examination of 33 feral goats from locations in New South Wales and South Australia found a Linguatula sp. nymph encased in the mesenteric lymph node of one goat from the Cooma region of New South Wales. The potential risk of transmission of Linguatula sp. to humans and other domestic animals is discussed. This study has highlighted the importance of continued surveys of feral animals for infection with parasites, especially as their distribution changes.

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An infective nymphal Linguatula sp. was collected from the lymph nodes of a feral goat in Australia.

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This is the first report of the feral goat as an intermediate host for Linguatula in Australia.

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Linguatula poses a zoonotic risk.

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The importance of continued surveys of parasites of feral animals is highlighted.

Characterization of tongue worms, Linguatula spp. (Pentastomida) in Romania, with the first record of an unknown adult Linguatula from roe deer (Capreolus capreolus Linnaeus)

Specimens of the pentastomid parasite, Linguatula serrata, have been reported from several animals in Romania, including some domestic dogs translocated to other parts of Europe. In this study, gray wolves (Canis lupus, n = 80), golden jackals (C. aureus, n = 115), red foxes (Vulpes vulpes, n = 236), and roe deer (Capreolus capreolus, n = 1) were examined for pentastomes. Overall, 17.5% of wolves were found to be infected with specimens of Linguatula, with a range of infections of one to five individuals per animal. Golden jackals and foxes had much lower infection levels, with 1.73% of golden jackals and 1.69% of foxes infected; both host species were found to be infected with one or two individual pentastomes per animal. The single deer specimen was infected with three individual pentastomes. The pentastomes collected from the wolves and golden jackals were determined to be immature and mature adult specimens of L. serrata based on morphological examination and molecular analysis using the 18S rRNA gene. No pentastomes collected from the red foxes were available for identification. The pentastomes collected from the roe deer were expected to be L. arctica but determined to be mature adult male specimens of an unknown Linguatula, herein, referred to as Linguatula sp. based on its morphology; the results of molecular sequencing for the Linguatula specimen collected from the deer were inconclusive, preventing a final species identification. This study presents the first report of L. serrata in any hosts from Romania through both morphological and molecular characterization, and also presents the first report of a Linguatula sp. in Ca. capreolus, utilizing morphological characterization. Issues of morphological variability are discussed, including the presence of spines in the hook pit of specimens of Linguatula. This study highlights the need to examine all specimens of Linguatula to confirm the stage of development. Despite the inconclusive molecular result for some specimens, the authors still urge future researchers to incorporate a combined molecular and morphological approach in identifying specimens of Linguatula.

Linguatula serrata in an imported dog in Germany: Single-case or emerging disease?

Linguatula serrata is a worm-like parasite with zoonotic potential that inhabits the nasal cavities of canids. Although most cases of linguatulosis are associated with unspecific and rather mild respiratory symptoms, cases of unusual infestations and severe courses in both animals and humans have been reported. In central and northern Europe, the pathogen used to appear only sporadically, however, within the last few years the number of detections has increased noticeably. In July 2020 an approximately nine-month-old dog, imported from Romania, was presented in a veterinary practice in Gotha, central Germany, due to persistent worsening cough. Despite antibiotic treatment the tussis became more severe until the dog expectorated multiple worm-like structures. Three of these specimens were sent to the Institute of Parasitology (Faculty of Veterinary Medicine, University of Leipzig, Leipzig) for morphological and genetic species identification. The latter was based on a 1000-bp fragment of the mitochondrial cytochrome c oxidase subunit I gene (cox1) and the complete nuclear 18S rRNA gene. The dog presented in this study suffered from a severe respiratory impairment caused by worm-like parasites inhabiting its upper respiratory tract. The detected parasites were morphologically identified as female specimens of the so-called tongue-worm L. serrata, which was confirmed by pairwise alignment and phylogenetic analysis of the produced sequences. We report an unusually severe case of L. serrata infection in an imported dog and discuss the spread of this potentially dangerous parasite in central and northern Europe.

28S rRNA sequences for Linguatula spp

Identification of specimens belonging to the genus Linguatula (Pentastomida) is relatively easy due to their unique morphology. However, differentiation between species of Linguatula can be challenging for several reasons, including considerable differences between different developmental stages of the parasite within and between species. Currently, 18S rRNA and Cox1 sequences are the only available comparable sequences in GenBank, but recent research has discussed the utility of 28S rRNA for pentastomid phylogenetics. This study presents 28S rRNA gene sequences for two members of the genus Linguatula. Sequences of 28S rRNA were successfully obtained from well-identified samples of L.serrata (collected in Australia) and L.nuttalli (collected in South Africa), with voucher specimens. Phylogenetic analysis of the 28S rRNA region showed 6% difference between L.serrata and L.nuttalli, with low levels of intraspecific variation. In comparison, 18S rRNA and Cox1 sequences from the same specimens showed 0.23% and 13% interspecific differences, respectively. The results of this study show that 28S rRNA has greater genetic diversity to allow for improved differentiation between species of Linguatula than 18S rRNA but is on par with Cox1. Records that do not provide adequate morphological or molecular data to justify independent specific diagnoses must be regarded cautiously, and the need for continued research on species of Linguatula, using a combined morphological and molecular analysis, across a number of different hosts, development stages, geographical regions and molecular markers is highlighted.

The first Linguatula serrata case in an imported dog in Finland

Linguatula serrata is a pentastomid parasite infecting carnivores as definitive hosts and herbivores as intermediate hosts. In carnivores, including dogs, it usually parasitises the nasal cavity and sinuses, causing upper respiratory signs. This case report presents the first canine Linguatula case in Finland in an imported dog originating from Spain. In addition to the unremarkable clinical history of the dog, the treatment, parasite's morphology and molecular analysis are described, and the zoonotic potential is discussed.

Verification of the Spotted-Tail Quoll, Dasyurus maculatus, as a Definitive Host for the Pentastomid Linguatula sp. in Australia

PURPOSE

Specimens of a pentastomid, identified as a nymphal Linguatula serrata, have previously been reported from the nasal cavity of the endangered Australian marsupial, the spotted-tail quoll, Dasyurus maculatus. These specimens were made available for morphological and molecular characterisation to confirm their species identity.

METHODS

Specimens were examined by light microscopy. Molecular sequencing attempts were unsuccessful.

RESULTS

Examination showed that the specimens were adult pentastomes of the genus Linguatula. Morphological differences are reported between these specimens and published measurements of specimens from other hosts collected from the same region.

CONCLUSIONS

This is the first confirmed report of an adult Linguatula pentastome in a native Australian animal. Due to the small number of specimens and the lack of successful molecular characterisation, the pentastomes have been referred to Linguatula sp. until future work can confirm the species identity. The need for combined molecular and morphological analysis of pentastome specimens is reiterated.