Museum material reveals a frog parasite emergence after the invasion of the cane toad in Australia

<p>Abstract</p> <p>Background</p> <p>A parasite morphologically indistinguishable from <it>Myxidium immersum </it>(Myxozoa: Myxosporea) found in gallbladders of the invasive cane toad (<it>Bufo marinus</it>) was identified in Australian frogs. Because no written record exists for such a parasite in Australian endemic frogs in 19^thand early 20^thcentury, it was assumed that the cane toad introduced this parasite. While we cannot go back in time ourselves, we investigated whether material at the museum of natural history could be used to retrieve parasites, and whether they were infected at the time of their collection (specifically prior to and after the cane toad translocation to Australia in 1935).</p> <p>Results</p> <p>Using the herpetological collection at the Australian Museum we showed that no myxospores were found in any animals (<it>n </it>= 115) prior to the cane toad invasion (1879-1935). The green and golden bell frog (<it>Litoria aurea</it>), the Peron's tree frog (<it>Litoria peronii</it>), the green tree frog (<it>Litoria caerulea</it>) and the striped marsh frog (<it>Limnodynastes peronii</it>) were all negative for the presence of the parasite using microscopy of the gallbladder content and its histology. These results were sufficient to conclude that the population was free from this disease (at the expected minimum prevalence of 5%) at 99.7% confidence level using the 115 voucher specimens in the Australian Museum. Similarly, museum specimens (<it>n </it>= 29) of the green and golden bell frog from New Caledonia, where it was introduced in 19^thcentury, did not show the presence of myxospores. The earliest specimen positive for myxospores in a gallbladder was a green tree frog from 1966. Myxospores were found in eight (7.1%, <it>n </it>= 112) frogs in the post cane toad introduction period.</p> <p>Conclusion</p> <p>Australian wildlife is increasingly under threat, and amphibian decline is one of the most dramatic examples. The museum material proved essential to directly support the evidence of parasite emergence in Australian native frogs. This parasite can be considered one of the luckiest parasites, because it has found an empty niche in Australia. It now flourishes in > 20 endemic and exotic frog species, but its consequences are yet to be fully understood.</p

Refugia or reservoir? Feral goats and their role in the maintenance and circulation of benzimidazole-resistant gastrointestinal nematodes on shared pastures

Gastrointestinal nematodes threaten the productivity of grazing livestock and anthelmintic resistance has emerged globally. It is broadly understood that wild ruminants living in sympatry with livestock act as a positive source of refugia for anthelmintic-susceptible nematodes. However, they might also act as reservoirs of anthelmintic-resistant nematodes, contributing to the spread of anthelmintic resistance at a regional scale. Here, we sampled managed sheep and cattle together with feral goats within the same property in New South Wales, Australia. Internal transcribed spacer 2 (ITS-2) nemabiome metabarcoding identified 12 gastrointestinal nematodes (Cooperia oncophora, Cooperia punctata, Haemonchus contortus, Haemonchus placei, Nematodirus spathiger, Ostertagia ostertagi, Teladorsagia circumcincta, Oesophagostomum radiatum, Oesophagostomum venulosum, Trichostrongylus axei, Trichostrongylus colubriformis and Trichostrongylus rugatus). Isotype-1 β-tubulin metabarcoding targeting benzimidazole resistance polymorphisms identified 6 of these nematode species (C. oncophora, C. punctata, H. contortus, H. placei, O. ostertagi and T. circumcincta), with the remaining 3 genera unable to be identified to the species level (Nematodirus, Oesophagostomum, Trichostrongylus). Both ITS-2 and β-tubulin metabarcoding showed the presence of a cryptic species of T. circumcincta, known from domestic goats in France. Of the gastrointestinal nematodes detected via β-tubulin metabarcoding, H. contortus, T. circumcincta, Nematodirus and Trichostrongylus exhibited the presence of at least one resistance genotype. We found that generalist gastrointestinal nematodes in untreated feral goats had a similarly high frequency of the benzimidazole-resistant F200Y polymorphism as those nematodes in sheep and cattle. This suggests cross-transmission and maintenance of the resistant genotype within the wild ruminant population, affirming that wild ruminants should be considered potential reservoirs of anthelmintic resistance

Rat lungworm (Angiostrongylus cantonensis) active larval emergence from deceased bubble pond snails (Bullastra lessoni) into water

Angiostrongylus cantonensis (the rat lungworm) is a zoonotic parasite of non-permissive accidental (dogs, humans, horses, marsupials, birds) hosts. The 3rd stage larvae (L3s) in the intermediate host (molluscs) act as the source of infection for accidental hosts through ingestion. Larvae can spontaneously emerge from dead gastropods (slugs and snails) in water, which are experimentally infective to rats. We sought to identify the time when infective A. cantonensis larvae can autonomously leave dead experimentally infected Bullastra lessoni snails. The proportion of A. cantonensis larvae that emerge from crushed and submerged B. lessoni is higher in snails 62 days post-infection (DPI) (30.3%). The total larval burden of snails increases at 91 DPI, indicating that emerged larvae subsequently get recycled by the population. There appears to be a window of opportunity between 1 and 3 months for infective larvae to autonomously escape dead snails. From a human and veterinary medicine viewpoint, the mode of infection needs to be considered; whether that be through ingestion of an infected gastropod, or via drinking water contaminated with escaped larvae

Extensive production of Neospora caninum tissue cysts in a carnivorous marsupial succumbing to experimental neosporosis

Experimental infections of Sminthopsis crassicaudata, the fat-tailed dunnart, a carnivorous marsupial widely distributed throughout the arid and semi-arid zones of Australia, show that this species can act as an intermediate host for Neospora caninum. In contrast to existing models that develop relatively few N. caninum tissue cysts, dunnarts offer a new animal model in which active neosporosis is dominated by tissue cyst production. The results provide evidence for a sylvatic life cycle of N. caninum in Australia between marsupials and wild dogs. It establishes the foundation for an investigation of the impact and costs of neosporosis to wildlife

Afternoon shedding of a new species of Isospora

The Regent Honeyeater (Xanthomyza phyrigia) is an endangered Australian bird species. Breeding populations have been established at Australian zoos in support of re-introduction programs. This species is the host of a new species of Isospora (Apicomplexa). Oocysts are spherical, 25.8 (22.5- 28.75) by 23.8 (20-26.25) µm with a colourless to pale yellow smooth wall undergoing rapid exogenous sporulation, 90% sporulated oocysts in 8 hours at 20 C. Each oocyst contains one polar granule. Sporocysts are ovoid, 18.67 (17-19) by 9.49 (9-10) µm with a flat Stieda body and spherical substieda body devoid of a hyaline body. The asexual stages and sexual phase is within the enterocytes of the duodenum and jejunum. Faeces collected in the morning (AM, n=84) and in the afternoon (PM, n=90) revealed significant diurnal periodicity in oocyst shedding; 21% (18 of 84) of the AM were positive with the mean of 499 oocysts.g-1 compared to the PM with 91% (82 of 90) bird faeces positive with the mean of 129,723 oocysts.g-1. Therefore, parasite checks for these birds should be carried out in the afternoon to obtain an accurate result. In conclusion, it is plausible that captive birds with high parasite burdens could be less likely selected by females for reproduction after release due to their duller plumage than their wild counterparts. Keywords: coccidia, Isospora, Regent Honeyeater, honeyeater, diurnal shedding, oocysts, recovery program

Parasite spread at the domestic animal - wildlife interface: anthropogenic habitat use, phylogeny and body mass drive risk of cat and dog flea (Ctenocephalides spp.) infestation in wild mammals

Spillover of parasites at the domestic animal - wildlife interface is a pervasive threat to animal health. Cat and dog fleas (Ctenocephalides felis and C. canis) are among the world's most invasive and economically important ectoparasites. Although both species are presumed to infest a diversity of host species across the globe, knowledge on their distributions in wildlife is poor. We built a global dataset of wild mammal host associations for cat and dog fleas, and used Bayesian hierarchical models to identify traits that predict wildlife infestation probability. We complemented this by calculating functional-phylogenetic host specificity to assess whether fleas are restricted to hosts with similar evolutionary histories, diet or habitat niches.Over 130 wildlife species have been found to harbour cat fleas, representing nearly 20% of all mammal species sampled for fleas. Phylogenetic models indicate cat fleas are capable of infesting a broad diversity of wild mammal species through ecological fitting. Those that use anthropogenic habitats are at highest risk. Dog fleas, by contrast, have been recorded in 31 mammal species that are primarily restricted to certain phylogenetic clades, including canids, felids and murids. Both flea species are commonly reported infesting mammals that are feral (free-roaming cats and dogs) or introduced (red foxes, black rats and brown rats), suggesting the breakdown of barriers between wildlife and invasive reservoir species will increase spillover at the domestic animal - wildlife interface.Our empirical evidence shows that cat fleas are incredibly host-generalist, likely exhibiting a host range that is among the broadest of all ectoparasites. Reducing wild species' contact rates with domestic animals across natural and anthropogenic habitats, together with mitigating impacts of invasive reservoir hosts, will be crucial for reducing invasive flea infestations in wild mammals

Climate change models predict southerly shift of the cat flea (Ctenocephalides felis) distribution in Australia

Abstract Background Bioclimatic variables play an integral part in the life-cycle of Ctenocephalides felis, the most common flea found on companion animals. It is essential that we understand the effects of climate on C. felis distribution as fleas are a major veterinary and public health concern. This study investigated the current distribution of C. felis in Australia and future projections based on climate modelling. Results Typing of C. felis was undertaken using the cytochrome c oxidase subunit 1 (cox1) mitochondrial DNA (mtDNA) region and current distribution of haplotypes was mapped by Maximum Entropy (Maxent) niche modelling. All C. felis haplotypes have been predicted to persist in environments along the eastern and southern coastlines of Australia and distinct ecological niches were observed for two C. felis haplogroups. Clade ‘Cairns’ haplogroup thrives under the northern coastal tropical conditions whilst Clade ‘Sydney’ haplogroup persists in temperate climates along the eastern and southern coasts. The model was then used to predict areas that are projected to have suitable climatic conditions for these haplogroups in 2050 and 2070 under the Intergovernmental Panel on Climate Change (IPCC) climate change scenarios. Under all IPCC Representative Concentration Pathways (RCP) climate change scenarios, the geographical range of all haplotypes was reduced by 5.59–42.21% in 2050 and 27.08–58.82% by 2070. The ranges of all clades were predicted to shift south along the eastern coastline. Conclusions As future temperatures exceed critical threshold temperatures for C. felis development in the northern tropical areas, Clade ‘Cairns’ haplogroup is predicted to shift south along the coastline and possibly outcompete the temperate haplogroup in these areas. If C. felis haplogroups possess distinct climatic niches it suggests a potential for these to be biologically distinct and have differing developmental rates and vector capabilities

Cryptosporidium parvum Mitochondrial-Type HSP70 Targets Homologous and Heterologous Mitochondria

A mitochondrial HSP70 gene (Cp-mtHSP70) is described for the apicomplexan Cryptosporidium parvum, an agent of diarrhea in humans and animals. Mitochondrial HSP70 is known to have been acquired from the proto-mitochondrial endosymbiont. The amino acid sequence of Cp-mtHSP70 shares common domains with mitochondrial and proteobacterial homologues, including 34 amino acids of an NH(2)-terminal mitochondrion-like targeting presequence. Phylogenetic reconstruction places Cp-mtHSP70 within the mitochondrial clade of HSP70 homologues. Using reverse transcription-PCR, Cp-mtHSP70 mRNA was observed in C. parvum intracellular stages cultured in HCT-8 cells. Polyclonal antibodies to Cp-mtHSP70 recognize a ∼70-kDa protein in Western blot analysis of sporozoite extracts. Both fluorescein- and immunogold-labeled anti-Cp-mtHSP70 localize to a single mitochondrial compartment in close apposition to the nucleus. Furthermore, the NH(2)-terminal presequence of Cp-mtHSP70 can correctly target green fluorescent protein to the single mitochondrion of the apicomplexan Toxoplasma gondii and the mitochondrial network of the yeast Saccharomyces cerevisiae. When this presequence was truncated, the predicted amphiphilic α-helix was shown to be essential for import into the yeast mitochondrion. These data further support the presence of a secondarily reduced relict mitochondrion in C. parvum

Multisystemic toxoplasmosis associated with a type II-like Toxoplasma gondii strain in a New Zealand fur seal (Arctocephalus forsteri) from New South Wales, Australia

We report the first confirmed case of toxoplasmosis in an Australian pinniped. Presence of Toxoplasma gondii DNA was detected in the brain of a free-ranging subadult New Zealand fur seal (Arctocephalus forsteri) with nonsuppurative meningoencephalitis, hypophysitis, posterior uveitis, retrobulbar cellulitis, and myocarditis associated with protozoan cysts and tachyzoites. The emaciated seal stranded moribund on a beach in northern Sydney in New South Wales. Histopathology coupled with specific immunohistochemistry and PCR assays confirmed the presence of T. gondii. The T. gondii sample (NZfs8825) identified in this study has an identical genotype as the type II (ToxoDB PCR-RFLP genotype #1) based on the direct sequencing and virtual RFLP of multilocus DNA markers including SAG1, 5'- and 3'-SAG2, alt.SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and Apico. Direct sequencing of T. gondii B1 DNA marker from the T. gondii sample (NZfs8825) identified a type II-like strain, based on presence of non-archetypal B1 gene polymorphisms previously reported as unique to Australia. This study suggests that T. gondii oocysts originating from mainland Australia, which has a large population of feral cats, may act as a disease threat to native marine fauna. Therefore, emerging toxoplasmosis in the Arctic has a relevant parallel in the Southern Ocean within Australian waters with yet unknown relevance to Antarctica