Brookes Victoria J, Jordan David, Davis Stephen, Ward Michael P, Heller Jane
Graham Centre for Agricultural Innovation, NSW Department of Primary Industries and Charles Sturt University, Pugsley Place, Wagga Wagga, NSW 2650, Australia.
School of Animal and Veterinary Sciences, Faculty of Science, Charles Sturt University, Wagga Wagga, NSW 2678, Australia.
PLoS One. 2015 Dec 29;10(12):e0146016. doi: 10.1371/journal.pone.0146016. eCollection 2015.
Strains of Shiga-toxin producing Escherichia coli O157 (STEC O157) are important foodborne pathogens in humans, and outbreaks of illness have been associated with consumption of undercooked beef. Here, we determine the most effective intervention strategies to reduce the prevalence of STEC O157 contaminated beef carcasses using a modelling approach.
A computational model simulated events and processes in the beef harvest chain. Information from empirical studies was used to parameterise the model. Variance-based global sensitivity analysis (GSA) using the Saltelli method identified variables with the greatest influence on the prevalence of STEC O157 contaminated carcasses. Following a baseline scenario (no interventions), a series of simulations systematically introduced and tested interventions based on influential variables identified by repeated Saltelli GSA, to determine the most effective intervention strategy.
Transfer of STEC O157 from hide or gastro-intestinal tract to carcass (improved abattoir hygiene) had the greatest influence on the prevalence of contaminated carcases. Due to interactions between inputs (identified by Saltelli GSA), combinations of interventions based on improved abattoir hygiene achieved a greater reduction in maximum prevalence than would be expected from an additive effect of single interventions. The most effective combination was improved abattoir hygiene with vaccination, which achieved a greater than ten-fold decrease in maximum prevalence compared to the baseline scenario.
Study results suggest that effective interventions to reduce the prevalence of STEC O157 contaminated carcasses should initially be based on improved abattoir hygiene. However, the effect of improved abattoir hygiene on the distribution of STEC O157 concentration on carcasses is an important information gap-further empirical research is required to determine whether reduced prevalence of contaminated carcasses is likely to result in reduced incidence of STEC O157 associated illness in humans. This is the first use of variance-based GSA to assess the drivers of STEC O157 contamination of beef carcasses.
产志贺毒素大肠杆菌O157（STEC O157）菌株是人类重要的食源性病原体，疾病暴发与食用未煮熟的牛肉有关。在此，我们使用建模方法确定最有效的干预策略，以降低受STEC O157污染的牛肉胴体的流行率。
一个计算模型模拟了牛肉收获链中的事件和过程。实证研究的信息用于对模型进行参数化。使用Saltelli方法的基于方差的全局敏感性分析（GSA）确定了对受STEC O157污染的胴体流行率影响最大的变量。在基线情景（无干预）之后，一系列模拟系统地引入并测试了基于重复的Saltelli GSA确定的有影响变量的干预措施，以确定最有效的干预策略。
STEC O157从牛皮或胃肠道转移到胴体（改善屠宰场卫生）对受污染胴体的流行率影响最大。由于输入之间的相互作用（由Saltelli GSA确定），基于改善屠宰场卫生的干预措施组合在最大流行率降低方面比单一干预措施的累加效应预期的更大。最有效的组合是改善屠宰场卫生并接种疫苗，与基线情景相比，最大流行率降低了十倍以上。
研究结果表明，降低受STEC O157污染的胴体流行率的有效干预措施最初应基于改善屠宰场卫生。然而，改善屠宰场卫生对STEC O157在胴体上浓度分布的影响是一个重要的信息空白——需要进一步的实证研究来确定受污染胴体流行率的降低是否可能导致人类STEC O157相关疾病发病率的降低。这是首次使用基于方差的GSA来评估牛肉胴体STEC O157污染的驱动因素。
