Domestic cats are the most important definitive hosts for Toxoplasma gondii, the agent of an important global zoonosis. Serial sera from cats orally inoculated either with T. gondii tissue cysts (n = 3) or sporulated oocysts (n = 3) and from 65 client-owned cats, plus sera from 1,757 client-owned cats presented to veterinarians in Switzerland were analysed for an antibody response to T. gondii by ELISA. Risk factors for seropositivity and prevalence were estimated with a generalised linear and beta regression model. The first model examined the association of an OD₄₀₅ value as the dependent variable, with gender, age, and outside access as possible independent variables. In the second model, we first analysed the data assuming a bimodal distribution representing two overlapping distributions of OD₄₀₅ values from positive and negative cats, enabling the assignment of a probability of true infection status to each cat. Mean probabilities of true infection status across groups represent an estimate of true prevalence. These probabilities were then regressed against age, gender and outside access. Antibody kinetics in cats orally inoculated with tissue cysts, shedding oocysts, did not differ significantly from those of cats inoculated with sporulated oocysts without detectable oocyst excretion, suggesting extraintestinal parasite invasion and exposure to tachyzoites in both situations at an early stage of infection. Analysis of serial serum samples suggested a persisting long-term humoral immune response. Of the client-owned cats, 42.4% (95% confidence interval (CI): 40.1–44.6) had a positive true infection status. This was higher (56.3% (95% CI: 53.2–59.6)) in cats with outside access than in those without (22.1% (95% CI: 18.9–25.4)). In the first model, the factors age (P < 0.0001), gender (male: P = 0.046), and outside access (P < 0.0001) were independently associated with significantly higher OD₄₀₅ values. In the second model, the probability of having a positive true infection status increased with age (P < 0.0001), was higher with outside access (P < 0.0001) and in outdoor male cats (P = 0.0006).

家猫是弓形虫最重要的最终宿主，弓形虫是一种重要的全球人畜共患病病原体。对口服接种弓形虫组织囊肿（n  = 3）或孢子化卵囊（n  = 3）的猫和 65 只客户拥有的猫的系列血清，以及来自瑞士兽医的 1,757 只客户拥有的猫的血清进行了分析ELISA对弓形虫的抗体反应。使用广义线性和β回归模型估计血清阳性和患病率的危险因素。第一个模型检查了 OD ₄₀₅的关联 值作为因变量，性别、年龄和外部访问作为可能的自变量。在第二个模型中，我们首先分析了数据，假设双峰分布代表 OD _{405 的}两个重叠分布来自阳性和阴性猫的值，从而能够为每只猫分配真实感染状态的概率。各组真实感染状态的平均概率代表真实流行率的估计值。然后根据年龄、性别和外部访问对这些概率进行回归。口服接种组织包囊、脱落卵囊的猫的抗体动力学与接种孢子化卵囊的猫的抗体动力学没有显着差异，而没有可检测到的卵囊排泄，这表明在感染的早期两种情况下，肠外寄生虫入侵和暴露于速殖子。对系列血清样本的分析表明存在持续的长期体液免疫反应。在客户拥有的猫中，42.4%（95% 置信区间 (CI)：40.1-44.6）具有阳性真实感染状态。这更高（56.3%（95% CI：53.2-59.6)) 在有外部通路的猫中比没有通路的猫 (22.1% (95% CI: 18.9-25.4))。在第一个模型中，因子年龄（P  < 0.0001）、性别（男性：P  = 0.046）和外部访问（P  < 0.0001）与显着更高的 OD ₄₀₅值独立相关。在第二个模型中，具有正的真正感染状态的概率随着年龄的（增加的P  <0.0001），被与外部访问（较高P  <0.0001）并在户外公猫（P  = 0.0006）。