Centre for Immunity, Infection and Evolution, University of Edinburgh, King's Buildings, UK.
Epidemics. 2012 Dec;4(4):171-8. doi: 10.1016/j.epidem.2012.09.001. Epub 2012 Sep 15.
Animal trade in industrialised livestock-production systems creates a complex, heterogeneous, contact network that shapes between-herd transmission of infectious diseases. We report the results of a simple mathematical model that explores patterns of spread and persistence of livestock-associated Methicillin-resistant Staphylococcus aureus (LA-MRSA) in the Danish pig-industry associated with this trade network. Simulations show that LA-MRSA can become endemic sustained by animal movements alone. Despite the extremely low predicted endemic prevalence, eradication may be difficult, and decreasing within-farm prevalence, or the time it takes a LA-MRSA positive farm to recover a negative status, fails to break long-term persistence. Our results suggest that a low level of non-movement induced transmission strongly affects MRSA dynamics, increasing endemic prevalence and probability of persistence. We also compare the model-predicted risk of 291 individual farms becoming MRSA positive, with results from a recent Europe-wide survey of LA-MRSA in holdings with breeding pigs, and find a significant correlation between contact-network connectivity properties and the model-estimated risk measure.
在工业化畜牧业生产系统中，动物贸易形成了一个复杂的、异质的接触网络，这种网络影响着传染病在畜群之间的传播。我们报告了一个简单数学模型的结果，该模型探索了与贸易网络相关的丹麦养猪业中与耐甲氧西林金黄色葡萄球菌（LA-MRSA）相关的传播和持续模式。模拟结果表明，仅通过动物运动，LA-MRSA 就可能成为地方性疾病。尽管预测的地方性流行率极低，但根除可能很困难，降低农场内的流行率，或者使 LA-MRSA 阳性农场恢复阴性状态所需的时间，并不能打破长期的持续存在。我们的结果表明，低水平的非运动诱导传播强烈影响 MRSA 的动态，增加了地方性流行率和持续存在的可能性。我们还将模型预测的 291 个个体农场发生 MRSA 阳性的风险与最近在有繁殖猪的农场进行的欧洲范围内 LA-MRSA 调查结果进行了比较，并发现接触网络连通性特性与模型估计的风险度量之间存在显著相关性。
