Transmission dynamics of pulmonary tuberculosis between autochthonous and immigrant sub-populations

<p>Abstract</p> <p>Background</p> <p>The overall incidence of tuberculosis (TB) in Western Europe has been declining since the 19^thCentury. 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.</p> <p>Methods</p> <p>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 (IS<it>6110 </it>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.</p> <p>Results</p> <p>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.</p> <p>Conclusion</p> <p>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.</p

Impact of Classroom Computer Availability on Preschoolers’ Social Interactions

Despite increases in computer availability in the classroom, very little data exists on computer availability and its use in Head Start classrooms. Therefore, the purpose of this study was to examine the impact of availability of computers on urban preschoolers’ naturally occurring social interactions in Head Start classrooms across one school year. The sample consisted of 66, predominantly African American, children in four urban, Head Start classrooms. A quasi-experimental design was employed in which three classrooms had computers, while one classroom served as the control. Naturally occurring social interactions were observed during free-play sessions over an 8-month period. Hierarchical linear modeling was used to analyze differences in social interactions across classrooms and school year. Results suggest that classroom computer availability may increase the interactive behavior of preschoolers. Results suggest that investing resources into a computer center in the Head Start classroom can have a positive effect on social development

Classroom Computers and Social Interaction among Low-Income Preschool Children

Despite increases in computer availability in the classroom, very little data exists on computer availability and its use in Head Start classrooms. Therefore, the purpose of this study was to examine the impact of availability of computers on urban preschoolers’ naturally occurring social interactions in Head Start classrooms across one school year. The sample consisted of 66, predominantly African American, lower income preschool children in four urban, Head Start classrooms. A design was employed in which three classrooms had computers, while one classroom served as the comparison group. Naturally occurring social interactions were observed during free-play sessions over an 8-month period. Differences in social interactions across classrooms and school year were analyzed. Results suggest that classroom computer availability may increase the interactive behavior of preschoolers. Implications of study findings for use of computer centers in the preschool classroom are discussed