Strachan Norval J C, Dunn Geoffrey M, Locking Mary E, Reid Thomas M S, Ogden Iain D
School of Biological Sciences, UK.
Int J Food Microbiol. 2006 Nov 1;112(2):129-37. doi: 10.1016/j.ijfoodmicro.2006.06.021. Epub 2006 Aug 28.
The three main pathways of Escherichia coli O157 infection are foodborne, environmental (including direct contact with animals and their faeces and contaminated water supplies) or person to person contact. The disease is often nicknamed the 'burger bug' but it appears that environmental risk factors may be more important. In this study we use four techniques (outbreak analysis, case-control studies, disease mapping and quantitative microbial risk assessment (QMRA)) to determine whether burgers or environmental pathways present the greater risk in Scotland. Analysis of E. coli O157 outbreaks in Scotland from 1994 to 2003 associated with either meat or dairy foods, or with environmental transmission shows that approximately 40% [M1] of these outbreaks were foodborne, 54% were environmental and 6% involved both transmission routes. However, the largest outbreaks tend to be foodborne accounting for 83% of outbreak cases. Case-control studies indicate strong risk associations with environmental exposure in Scotland, the UK as a whole and the USA, but burgers appear to be more of a risk in the USA. Canadian, Scottish and Swedish disease mapping studies found positive association with indicators of cattle density. In Grampian (North-East Scotland) we found that there was a positive association with cattle and sheep density (divided by human population density) as well as percentage of population on private water supplies. We found 63% of cases in rural postcodes compared with 37% urban after correcting for population differences suggesting that at least 26% of cases may be classified as environmental. QMRA showed that on average, the risk was 100 times greater when visiting a pasture than eating a burger in Grampian. However, it is difficult to determine which pathway actually causes most illnesses as it is unknown how many burgers are consumed daily and what is the frequency of human visits to pasture. The implementation of hygienic food processing post-1996 Central Scotland outbreak and the preference for 'well done' burgers may account for this food being a relatively low risk thus making the 'burger bug' term less appropriate in the UK.
大肠杆菌O157感染的三条主要途径是食源性、环境性（包括直接接触动物及其粪便以及受污染的水源）或人际接触。这种疾病常被昵称为“汉堡病菌”，但环境风险因素似乎更为重要。在本研究中，我们使用四种技术（暴发分析、病例对照研究、疾病绘图和定量微生物风险评估（QMRA））来确定在苏格兰，汉堡途径还是环境途径带来的风险更大。对1994年至2003年苏格兰与肉类或奶制品相关的、或通过环境传播的大肠杆菌O157暴发进行分析表明，这些暴发中约40%是食源性的，54%是环境性的，6%涉及两种传播途径。然而，规模最大的暴发往往是食源性的，占暴发病例的83%。病例对照研究表明，在苏格兰、整个英国和美国，环境暴露与风险有很强的关联，但在美国，汉堡似乎风险更大。加拿大、苏格兰和瑞典的疾病绘图研究发现，与牛密度指标呈正相关。在格兰扁（苏格兰东北部），我们发现与牛和羊的密度（除以人口密度）以及使用私人供水的人口百分比呈正相关。在校正人口差异后，我们发现农村邮政编码地区的病例占63%，城市地区占37%，这表明至少26%的病例可归类为环境性病例。QMRA显示，在格兰扁，平均而言，参观牧场时的风险比吃汉堡高100倍。然而，很难确定哪种途径实际上导致了大多数疾病，因为每日食用汉堡的数量以及人们参观牧场的频率尚不清楚。1996年后苏格兰中部暴发疫情后实施的卫生食品加工措施以及对“熟透”汉堡的偏好，可能是这种食品风险相对较低的原因，因此在英国，“汉堡病菌”这一说法不太恰当。
