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.

弓形虫被认为是许多澳大利亚本土物种的疾病风险。野猫是澳大利亚弓形虫的主要最终宿主，因此，对猫种群中弓形虫的流行病学进行调查对于了解野生动物构成的风险至关重要。对于针对猫中弓形虫的诊断测试，测试灵敏度和特异性的定义很差，因此需要经过验证的技术。这项研究的重点是澳大利亚维多利亚州菲利普岛的野猫种群。我们将新型实时PCR（qPCR）方案与改良的凝集试验（MAT）进行了比较，并使用贝叶斯潜伏类建模方法来评估每种测定法的诊断参数并评估其真实发生率。T. gondii在野猫中。此外，我们进行了多变量logistic回归分析，以确定与猫刚地弓形虫感染相关的危险因素。通过qPCR和MAT进行的弓形虫总体患病率分别为79.5％（95％置信区间72.6-85.0）和91.8％（84.6-95.8）。贝叶斯模型估计MAT的敏感性和特异性分别为96.2％（95％可信区间91.8-98.8）和82.1％（64.9-93.6），而qPCR分别为90.1％（83.6-95.5）和96.0％（82.1-99.8），分别。在菲利普岛上的野生猫中，弓形虫感染的真实患病率估计为90.3％（83.2-95.1）。多变量logistic回归分析表明弓形虫感染与体重呈正相关，这种影响会随着季节而改变。不论体重如何，冬季困在家中的猫都有很高的感染几率。本研究表明，将qPCR应用于组织是对野生猫种群中弓形虫进行测试的高度灵敏，特异且在逻辑上可行的工具。此外，弓形虫感染在菲利普岛上的野猫中非常普遍，这可能对地方性和引入的有袋动物种群产生重大影响。