Section Clinical Tropical Medicine, Department for Infectious Diseases, University Hospital Heidelberg, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany.
BMC Infect Dis. 2009 Dec 4;9:197. doi: 10.1186/1471-2334-9-197.
The overall incidence of tuberculosis (TB) in Western Europe has been declining since the 19th Century. However, immigrant sub-groups from high-prevalence countries are slowing down this trend. The aim of this study was to describe how immigration influences TB transmission in Germany. For that we prospectively investigated the dynamics of TB transmission between TB high-prevalence immigrant and TB low-prevalence local populations with molecular epidemiological methods and conventional contact investigations. Besides, we assessed transmission in relation to social mixing using an innovative tool that measures the integration of immigrants into the local social environment.
A prospective study of confirmed culture positive cases of pulmonary TB and their contacts was carried out in a German federal state from 2003 to 2005. Data for the study included: 1) case data routinely collected by the local public health staff and transmitted to the state health office and the national surveillance centre, 2) a study questionnaire designed to capture social interactions of relevance for TB transmission and 3) molecular genotyping data (IS6110 DNA fingerprint and spoligotyping). The proportion of German cases caused by foreign-born cases, and vice versa, was estimated and an integration index was computed using a selected set of questions from the study questionnaire.
A total of 749 cases of culture-positive pulmonary tuberculosis voluntarily enrolled in the study, representing 57.8% of all registered cases diagnosed over the study period. Data that included study questionnaire and DNA fingerprinting were available for 41% (n = 308) of the study participants. Forty-seven clusters, defined as a least two cases infected by the same TB strains, were identified by molecular methods and included 132 (17%) of the study participants. Epidemiological links were identified for 28% of the clusters by conventional epidemiological data. In mixed clusters, defined as clusters including German and foreign-born individuals, the probability of cases to be caused by foreign-born cases was estimated at 18.3%. We observed a trend to mixed clusters with increasing time spent by immigrants in the host country. This group also presented comparatively higher integration indexes than immigrants in immigrant-only clusters.
Our results confirm the findings of other studies that there is no significant TB transmission from TB high-prevalence immigrant to TB low-prevalence autochthonous population. This may be explained by the good performance of tuberculosis screening programmes for certain groups arriving in Germany from high- prevalence countries, by a low degree of mixing of immigrants with the local population or by a combination of both.
自 19 世纪以来，西欧的结核病（TB）总发病率一直在下降。然而，来自高发病率国家的移民亚群正在减缓这一趋势。本研究的目的是描述移民如何影响德国的结核病传播。为此，我们采用分子流行病学方法和常规接触调查，前瞻性研究了来自高发病率移民和低发病率本地人群之间的结核病传播动态。此外，我们还使用一种创新工具评估了与社会融合相关的传播情况，该工具可衡量移民融入当地社会环境的程度。
我们在德国一个联邦州进行了一项针对确诊的肺结核病培养阳性病例及其接触者的前瞻性研究，研究时间为 2003 年至 2005 年。研究数据包括：1）当地公共卫生人员常规收集并传输到州卫生办公室和国家监测中心的病例数据；2）一份旨在捕获与结核病传播相关的社会互动的研究问卷；3）分子基因分型数据（IS6110 DNA 指纹图谱和 spoligotyping）。估计了由外国出生病例引起的德国病例比例和反之亦然，并使用研究问卷中的一组选定问题计算了融合指数。
共有 749 例培养阳性肺结核病患者自愿参加了该研究，占研究期间登记的所有病例的 57.8%。包括研究问卷和 DNA 指纹图谱的数据可用于 41%（n=308）的研究参与者。通过分子方法确定了 47 个簇，定义为至少有两个病例感染了相同的结核菌株，这些簇包括 132 名（17%）研究参与者。通过常规流行病学数据确定了 28%的簇的流行病学联系。在混合簇中，定义为包括德国人和外国出生者的簇，外国出生者引起的病例的概率估计为 18.3%。我们观察到随着移民在东道国停留时间的增加，混合簇的趋势。与仅由移民组成的簇相比，该组的融合指数也相对较高。
我们的结果证实了其他研究的发现，即来自高发病率移民的结核病向低发病率的当地人群传播没有显著意义。这可能是由于德国对来自高发病率国家的某些群体实施了良好的结核病筛查计划，移民与当地人口的混合程度较低，或者两者的结合。
