Recent Transmission of Tuberculosis and Related Social-demographic Determinants in Taiwan: a Spatial Analysis
Date Issued
2009
Date
2009
Author(s)
NG, IN-CHAN
Abstract
Backgrounduberculosis (TB) remains a major global health problem. Although the global TB incidence peaked in 2003, total number of deaths and cases are still rising due to population growth. In Taiwan, the number of TB reported case is highest among all infectious diseases. Previously it was believed that reactivation was the major mechanism for tuberculosis development, and so epidemiological research and contact investigation were regarded as less important control measures. However, from the fact that the risk of becoming active disease is the highest in the first two years after infection, and from genotyping results that there is a substantial proportion of clustered isolates; these imply that incidence of TB could be due to recent transmission rather than reactivation. In this way, early detection would be important to block transmission and targeted local area screening would be a more cost-effective method to achieve it.tudy Aimy means of spatial statistic methods, we would like to find out if recent transmission exists in Taiwan as well as where recent transmission takes place. ethodse explored if there was spatial dependency of TB cumulative incidence in the township level by spatial lag regression model. Significance of the spatial lag variable after controlling other variables inferred recent transmission in the township level. Using point data, we also detected TB spatial clusters in Taipei by means of Nearest Neighbor Hierarchical Clustering (NNH) and Spatial Scan Statistics. Recent transmission might take place where clusters could still be detected after adjusting for total population and elderly population. Spoligotyping and MIRU-VNTR assay were used to differentiate isolates of M. tuberculosis for the TB cases in the clusters.esultsn the spatial lag model, spatial lag parameters were significant after adjusting for other variables. TB cumulative incidence of neighboring townships had substantial effect on that of itself which implied that recent transmission existed on a global scale. By means of cluster detection method, after adjusting for total population and elderly population, clusters could still be found, thus rejecting the hypothesis that active TB cases were originated from reactivation of latent TB. Recent transmission took place where the clusters were found. Genotyping result reinforced this interpretation.onclusionsoth township-level analysis and point-data analysis strongly indicated that recent TB transmission occurred at community in Taiwan. Using spatial analysis and genotyping techniques can be an effective method for identifying discrete geographic areas in which on-going TB transmission is likely to occur.
Subjects
tuberculosis
recent transmission
spatial analysis
geographic information system (GIS)
spatial cluster detection
SDGs
Type
thesis
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