National Institute of Public Health and the Environment, Antonie van Leeuwenhoeklaan 9, Bilthoven, The Netherlands.
Int J Food Microbiol. 2010 Dec 15;144(2):243-9. doi: 10.1016/j.ijfoodmicro.2010.09.026. Epub 2010 Oct 30.
Salmonella is a key human pathogen worldwide, most often associated with food poisoning incidences. There is a small number of predominant serotypes found in human cases. The role of exposure in the epidemiology of Salmonella can be explained using dose-response assessment both for infection and acute enteric illness. Dose-response studies are traditionally based on human challenge experiments but an alternative is to use outbreak data. Such data were collected from the published literature which included estimates of the dose ingested and the attack rate. Separate dose-response models for infection and illness given infection were fitted using a multi-level statistical framework. These models incorporated serotype and susceptibility as categorical covariates, and adjusted for heterogeneity in exposure. The results indicate that both the risk of infection and the risk of illness given infection increase with dose. The dose-response model incorporating data from all outbreaks had an infection ID50 of 7 CFU's and illness ID50 of 36 CFUs. This is indicative of much higher infectivity and pathogenicity compared with feeding studies of healthy human volunteers with laboratory adapted strains. No differences were found in the outbreak models between serotypes and susceptibility categories. However, for serotypes other than S. Enteritidis or S. Typhimurium, results indicate that a minor proportion of individuals exposed will not fall ill even at high doses. The dose-response relations indicate that outbreaks are associated with higher doses making it more likely to have a higher attack rate. Applications of the dose-response model in outbreak situations where either dose or attack rate is missing were successfully used to clarify the epidemiology. Finally, the dose-response models described here can be readily used in quantitative microbiological risk assessment to predict human infection and illness rates. A simple Excel spreadsheet implementing the model has been prepared and is available from the authors.
沙门氏菌是全球范围内的主要人类病原体，通常与食物中毒事件有关。在人类病例中发现了少数主要血清型。可以使用感染和急性肠道疾病的剂量反应评估来解释暴露在沙门氏菌流行病学中的作用。剂量反应研究传统上基于人体挑战实验，但另一种方法是使用暴发数据。这些数据是从已发表的文献中收集的，其中包括摄入剂量和攻击率的估计值。使用多水平统计框架分别为感染和感染后疾病拟合了感染和疾病的剂量反应模型。这些模型将血清型和易感性作为分类协变量纳入其中，并针对暴露的异质性进行了调整。结果表明，感染的风险和感染后患病的风险都随剂量增加而增加。纳入所有暴发数据的剂量反应模型的感染 ID50 为 7 CFU，疾病 ID50 为 36 CFU。这表明与用实验室适应株喂养健康人体志愿者的喂养研究相比，感染性和致病性要高得多。在暴发模型中，在血清型和易感性类别之间未发现差异。但是，对于除肠炎沙门氏菌或鼠伤寒沙门氏菌以外的血清型，结果表明，即使在高剂量下，暴露的少数个体也不会生病。剂量反应关系表明，暴发与较高剂量有关，因此更有可能出现较高的攻击率。在剂量或攻击率缺失的暴发情况下成功应用剂量反应模型来阐明流行病学。最后，可以在定量微生物风险评估中轻松使用此处描述的剂量反应模型来预测人类感染和疾病率。作者已经准备了一个简单的 Excel 电子表格来实现该模型，并可供作者使用。
