Comparison of the modified agglutination test and real-time PCR for detection of Toxoplasma gondii exposure in feral cats from Phillip Island, Australia, and risk factors associated with infection

Toxoplasma gondii is considered a disease risk for many native Australian species. Feral cats are the key definitive host of T. gondii in Australia and therefore, investigating the epidemiology of T. gondii in cat populations is essential to understanding the risk posed to wildlife. Test sensitivity and specificity are poorly defined for diagnostic tests targeting T. gondii in cats and there is a need for validated techniques. This study focused on the feral cat population on Phillip Island, Victoria, Australia. We compared a novel real-time PCR (qPCR) protocol to the modified agglutination test (MAT) and used a Bayesian latent class modelling approach to assess the diagnostic parameters of each assay and estimate the true prevalence of T. gondii in feral cats. In addition, we performed multivariable logistic regression to determine risk factors associated with T. gondii infection in cats. Overall T. gondii prevalence by qPCR and MAT was 79.5% (95% confidence interval 72.6-85.0) and 91.8% (84.6-95.8), respectively. Bayesian modelling estimated the sensitivity and specificity of the MAT as 96.2% (95% credible interval 91.8-98.8) and 82.1% (64.9-93.6), and qPCR as 90.1% (83.6-95.5) and 96.0% (82.1-99.8), respectively. True prevalence of T. gondii infection in feral cats on Phillip Island was estimated as 90.3% (83.2-95.1). Multivariable logistic regression analysis indicated that T. gondii infection was positively associated with weight and this effect was modified by season. Cats trapped in winter had a high probability of infection, regardless of weight. The present study suggests qPCR applied to tissue is a highly sensitive, specific and logistically feasible tool for T. gondii testing in feral cat populations. Additionally, T. gondii infection is highly prevalent in feral cats on Phillip Island, which may have significant impacts on endemic and introduced marsupial populations

Eimeria trichosuri: Phylogenetic position of a marsupial coccidium, based on 18S rDNA sequences

Phylogenetic analysis of the genus Eimeria suggests that parasite and host have coevolved over broad evolutionary timescales. Here we extend this analysis by determining the 18S rDNA gene sequence of the marsupial coccidium, Eimeria trichosuri, and assessing its phylogenetic position relative to Eimeria from birds, reptiles and placental mammals. This analysis placed E. trichosuri clones in a clade that diverged before the major clade comprising species from placental mammals. The position of E. trichosuri is consistent with host phylogeny where marsupials represent an ancient evolutionary line that predates the placental mammal line.4 page(s

Pacific Gulls (<i>Larus pacificus</i>) as Potential Vectors of <i>Coxiella burnetii</i> in an Australian Fur Seal Breeding Colony

Recently, Coxiella burnetii has been described as a novel pathogen potentially contributing to decreased pup production in Australian fur seals (AusFS, Arctocephalus pusillus doriferus). Pacific gulls (PGs, Larus pacificus) are known to scavenge AusFS placental material during the fur seal breeding season. It is hypothesized that PGs may act as vectors for this pathogen. In the present study, cloacal swabs, oral swabs and serum were collected from PGs on Kanowna Island (KI, an AusFS breeding colony) and a nearby island, Seal Island (SI), not occupied by pinnipeds. All sample sets were evaluated with qPCR for the com1, htpAB and IS1111 markers. Most oral and cloacal swabs from KI tested positive on both the com1 (94.1%; 88.2%) and htpAB targets (76.5%; 76.5%). Amplification was very low from the SI oral swabs and cloacal swabs. Only the KI serum samples had amplification (17.7% for both com1 and htpAB). There was no IS1111 amplification in either colony. The results demonstrate that PGs can potentially act as vectors for the spread of C. burnetii. In some birds, C. burnetii was detectable in the serum, indicating that gulls can experience bacteraemia. It appears that different feeding strategies in the same species within the same ecosystem can have profound effects on the prevalence of pathogens. Further studies are required to better understand the epidemiology and potential risks of this organism

Virus survey in populations of two subspecies of bent-winged bats (<i>Miniopterus orianae bassanii</i> and <i>oceanensis</i>) in south-eastern Australia reveals a high prevalence of diverse herpesviruses

<div><p>While bats are often viewed as carriers of infectious disease agents, little research has been conducted on the effects these potential pathogens may have on the bat populations themselves. The southern bent-winged bat (<i>Miniopterus orianae bassanii</i>) is a critically endangered subspecies endemic to south-eastern Australia. Population numbers of this bat have been declining for the past 50 years, but the reasons for this are unclear. As part of a larger study to determine if disease could be a contributing factor to this decline, 351 southern bent-winged bats from four locations were captured, and oral swabs were collected and tested for the presence of potentially pathogenic viruses. Results were compared with those obtained from 116 eastern bent-winged bats (<i>Miniopterus orianae oceanensis</i>) from three different locations. The eastern bent-winged bat is a related but more common and widespread subspecies whose geographical range overlaps partly with southern bent-winged bats. Herpesviruses were detected in bent-winged bats from all seven locations. At least six novel herpesviruses (five betaherpesviruses and one gammaherpesvirus) were identified. The prevalence of herpesvirus infection was higher in eastern bent-winged bats (44%, 51/116), compared to southern bent-winged bats (27%, 95/351), although this varied across the locations and sampling periods. Adenoviruses and a range of different RNA viruses (lyssaviruses, filoviruses, coronaviruses and henipaviruses) were also tested for but not detected. The detected herpesviruses did not appear to be associated with obvious ill health, and may thus not be playing a role in the population decline of the southern bent-winged bat. The detection of multiple novel herpesviruses at a high prevalence of infection is consistent with our understanding of bats as hosts to a rich diversity of viruses.</p></div

Prevalence of herpesvirus DNA in oropharyngeal swabs, including proportion of sequence-confirmed positive swabs (confirmed), collected from populations of southern and eastern bent-winged bats from south-eastern Australia.

<p>All bats are adults unless otherwise indicated.</p

Phylogenetic tree demonstrating the relationship between six bent-winged bat herpesviruses detected in southern and eastern bent-winged bats from south-eastern Australia using PCR, and a selection of viruses from the <i>Alpha</i>- (red), <i>Beta</i>- (blue) and <i>Gammaherpesvirinae</i> (purple) subfamilies.

<p>The tree was generated from the 45 amino acid long alignment using MrBayes v3.2.6 [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0197625#pone.0197625.ref047" target="_blank">47</a>] with four heated chains, a chain length of 1,000,000, sampling every 10,000 iterations, and a burn in of 10%. GenBank accession numbers are located to the right of each virus.</p

Comparison of bent-winged bat (BWB) herpesvirus sequences, detected by PCR analysis, from southern and eastern bent-winged bats from south-eastern Australia, with the bat herpesvirus in GenBank with the closest identity.

<p>Comparison of bent-winged bat (BWB) herpesvirus sequences, detected by PCR analysis, from southern and eastern bent-winged bats from south-eastern Australia, with the bat herpesvirus in GenBank with the closest identity.</p

Distribution of herpesviruses detected in each of the seven bent-winged bat locations sampled across Victoria and South Australia (southern bent-winged bat: Naracoorte, Portland 1 & 2, Allansford; and eastern bent-winged bat: Christmas Hills, Eildon and Lakes Entrance).

<p>Numbers represent the number of viruses of each type present in the population. D15-like viruses = green. NG46-like viruses = orange. N7050-like viruses = blue. CH20-like viruses = maroon. E22-like viruses = lilac. CH6-like viruses = salmon.</p