Gautam R, Kulow M, Park D, Gonzales T K, Dahm J, Shiroda M, Stasic A J, Döpfer D, Kaspar C W, Ivanek R
Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences,Texas A&M University,College Station, TX,USA.
College of Veterinary Medicine,University of Wisconsin,Madison, WI,USA.
Epidemiol Infect. 2015 Jan;143(2):274-87. doi: 10.1017/S0950268814000867. Epub 2014 Apr 14.
A pen infection-transmission experiment was conducted to elucidate the role of pathogen strain and environmental contamination in transmission of Escherichia coli O157:H7 (ECO157) in cattle. Five steers were inoculated with a three-strain mixture of ECO157 and joined with five susceptible steers in each of two experimental replicates. Faecal and environmental samples were monitored for ECO157 presence over 30 days. One ECO157 strain did not spread. Transmission rates for the other two strains were estimated using a generalized linear model developed based on a modified 'Susceptible-Infectious-Susceptible' mathematical model. Transmission rates estimated for the two strains (0·11 and 0·14) were similar. However, the rates significantly (P = 0·0006) increased 1·5 times for every 1-unit increase in the level of environmental contamination measured as log10 c.f.u. Depending on the level of environmental contamination, the estimated basic reproduction numbers varied from <1 to 8. The findings indicate the importance of on-farm measures to reduce environmental contamination for ECO157 control in cattle that should be validated under field conditions.
进行了一项围栏感染传播实验，以阐明病原体菌株和环境污染在牛群中大肠杆菌O157:H7（ECO157）传播中的作用。给五头公牛接种了ECO157的三菌株混合物，并在两个实验重复中分别与五头易感公牛合群。在30天内监测粪便和环境样本中ECO157的存在情况。一种ECO157菌株没有传播。使用基于改良的“易感-感染-易感”数学模型开发的广义线性模型估计了其他两种菌株的传播率。估计的两种菌株的传播率（0·11和0·14）相似。然而，以log10 c.f.u.衡量的环境污染水平每增加1个单位，传播率显著（P = 0·0006）增加1·5倍。根据环境污染水平，估计的基本繁殖数从<1到8不等。研究结果表明，在农场采取措施减少环境污染对于牛群中ECO157的控制非常重要，这应在田间条件下进行验证。
