一项研究提出，给奶牛接种疫苗防范大肠埃希氏菌O157可能减少将近85%的人类大肠埃希氏菌感染病例，这种感染导致了严重的胃肠疾病和死亡。Louise Matthews及其同事使用兽医数据、人类监测数据和分子数据研究了大肠埃希氏菌O157从奶牛传给人的风险，并且估计了为牛这种大肠埃希氏菌感染的主要储存宿主接种疫苗的效率。有两种针对这种细菌的疫苗，能减少牛在其粪中排出这种细菌的频率、时间和数量。然而，成本和管理问题妨碍了这些疫苗的广泛使用。这组作者证明了只有在奶牛在粪便中排出大量的这种细菌的罕见环境下，人感染大肠埃希氏菌O157的风险才是重大的。由于目前可用的疫苗针对细菌排出率，这组作者预测说，为牛接种疫苗可能减少人感染大肠埃希氏菌的病例将近85%，这远远高于关于这些疫苗对牛的效率的研究预测的50%的数字。这组作者说，这些发现强有力地支持了畜牧业采用这些疫苗。（生物谷 Bioon.com）
生物谷推荐的英文摘要
PNAS doi: 10.1073/pnas.1304978110
Predicting the public health benefit of vaccinating cattle against Escherichia coli O157
Louise Matthewsa,1, Richard Reevea,b, David L. Gallyc, J. Chris Lowd, Mark E. J. Woolhousee, Sean P. McAteerc, Mary E. Lockingf, Margo E. Chase-Toppinge, Daniel T. Haydona, Lesley J. Allisong, Mary F. Hansong, George J. Gunnh, and Stuart W. J. Reidi
Identifying the major sources of risk in disease transmission is key to designing effective controls. However, understanding of transmission dynamics across species boundaries is typically poor, making the design and evaluation of controls particularly challenging for zoonotic pathogens. One such global pathogen is Escherichia coli O157, which causes a serious and sometimes fatal gastrointestinal illness. Cattle are the main reservoir for E. coli O157, and vaccines for cattle now exist. However, adoption of vaccines is being delayed by conflicting responsibilities of veterinary and public health agencies, economic drivers, and because clinical trials cannot easily test interventions across species boundaries, lack of information on the public health benefits. Here, we examine transmission risk across the cattle–human species boundary and show three key results. First, supershedding of the pathogen by cattle is associated with the genetic marker stx2. Second, by quantifying the link between shedding density in cattle and human risk, we show that only the relatively rare supershedding events contribute significantly to human risk. Third, we show that this finding has profound consequences for the public health benefits of the cattle vaccine. A naïve evaluation based on efficacy in cattle would suggest a 50% reduction in risk; however, because the vaccine targets the major source of human risk, we predict a reduction in human cases of nearly 85%. By accounting for nonlinearities in transmission across the human–animal interface, we show that adoption of these vaccines by the livestock industry could prevent substantial numbers of human E. coli O157 cases.
