Department of Animal and Public Health, School of Veterinary Medicine, Universidad Nacional Mayor de San Marcos, Lima, Peru.
Tropical and Highlands Veterinary Research Institute, Universidad Nacional Mayor de San Marcos, Lima, Peru.
PLoS One. 2022 Mar 14;17(3):e0264898. doi: 10.1371/journal.pone.0264898. eCollection 2022.
Taenia solium is an important cause of acquired epilepsy worldwide and remains endemic in Asia, Africa, and Latin America. Transmission of this parasite is still poorly understood despite the design of infection experiments to improve our knowledge of the disease, with estimates for critical epidemiological parameters, such as the probability of human-to-pig infection after exposure to eggs, still lacking. In this paper, a systematic review was carried out and eight pig infection experiments were analyzed to describe the probability of developing cysts. These experiments included different pathways of inoculation: with ingestion of proglottids, eggs, and beetles that ingested eggs, and direct injection of activated oncospheres into the carotid artery. In these experiments, different infective doses were used, and the numbers of viable and degenerated cysts in the body and brain of each pig were registered. Five alternative dose-response models (exponential, logistic, log-logistic, and exact and approximate beta-Poisson) were assessed for their accuracy in describing the observed probabilities of cyst development as a function of the inoculation dose. Dose-response models were developed separately for the presence of three types of cysts (any, viable only, and cysts in the brain) and considered for each of the four inoculation methods ("Proglottids", "Eggs", "Beetles" and "Carotid"). The exact beta-Poisson model best fit the data for the three types of cysts and all relevant exposure pathways. However, observations for some exposure pathways were too scarce to reliably define a dose-response curve with any model. A wide enough range of doses and sufficient sample sizes was only found for the "Eggs" pathway and a merged "Oral" pathway combining the "Proglottids", "Eggs" and "Beetles" pathways. Estimated parameter values from this model suggest that a low infective dose is sufficient to result in a 50% probability for the development of any cyst or for viable cyst infections. Although this is a preliminary model reliant on a limited dataset, the parameters described in this manuscript should contribute to the design of future experimental infections related to T. solium transmission, as well as the parameterization of simulation models of transmission aimed at informing control.
猪带绦虫是全世界获得性癫痫的一个重要病因，在亚洲、非洲和拉丁美洲仍然流行。尽管为了增进对这种疾病的了解设计了感染实验，但这种寄生虫的传播仍未得到很好的理解，关键的流行病学参数（例如，暴露于虫卵后人类感染猪的概率）仍未得到估计。本文进行了系统评价，并分析了 8 个猪感染实验，以描述形成囊尾蚴的概率。这些实验包括不同的接种途径：摄入孕节、虫卵和摄入虫卵的甲虫，以及将活化的六钩蚴直接注入颈动脉。在这些实验中，使用了不同的感染剂量，并记录了每头猪体内和脑中存活和退化的囊尾蚴数量。评估了 5 种替代剂量反应模型（指数、逻辑、对数逻辑和精确和近似贝塔泊松），以确定它们在描述观察到的囊尾蚴发育概率与接种剂量的关系方面的准确性。为存在的三种类型的囊尾蚴（任何类型、仅存活的和脑中的囊尾蚴）分别开发了剂量反应模型，并考虑了四种接种方法（“孕节”、“虫卵”、“甲虫”和“颈动脉”）中的每一种。精确的贝塔泊松模型最适合三种类型的囊尾蚴和所有相关暴露途径的数据。然而，对于某些暴露途径的观察结果太少，无法使用任何模型可靠地定义剂量反应曲线。只有“虫卵”途径和合并的“口服”途径（合并“孕节”、“虫卵”和“甲虫”途径）发现了足够宽的剂量范围和足够的样本量。从该模型估计的参数值表明，低感染剂量足以使任何囊尾蚴或存活的囊尾蚴感染的发展概率达到 50%。尽管这是一个依赖于有限数据集的初步模型，但本文描述的参数应有助于设计与猪带绦虫传播相关的未来实验感染，并有助于参数化旨在提供控制信息的传播模拟模型。
