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Setting: A retrospective study in an urban setting with a high tuberculosis incidence., Objective: To study the molecular epidemiology and disease dynamics of a prevalent Mycobacterium tuberculosis strain family, F29, a subset of the Beijing strains., Design: Multi-locus DNA fingerprinting and genomic analysis was used to characterise F29 isolates. Demographic and molecular epidemiologic data were correlated with those of other isolates from the setting. The geographic locations of five F29 strain clusters were plotted using a geographic information system (GIS) and an index for geographic distribution was calculated. Their cumulative temporal occurrence was also plotted., Results: The genomic similarity of F29 to the Beijing-strains was confirmed. A high degree of clustering predicted high disease transmission. Spatial distribution was mostly widespread except for one cluster. Smaller foci of transmission were observed. The temporal spread showed ongoing transmission., Conclusion: F29 belongs to the Beijing strain group. The prevalence and high degree of strain clustering, with limited geographic clustering, indicates that F29 strains are endemic in the study community. However, recent epidemiologic events also contributed to the disease spread. The combination of molecular epidemiologic, spatial and temporal data has enhanced our understanding of the disease dynamics of Beijing strains in our study community.

Background Epidemiological studies have shown an inverse relation of mycobacterial infection and the frequency of allergic diseases and asthma. Recent evidence suggests that allergic inflammation may be inhibited in the presence of chronic and persistent infections, such as that by Mycobacterium tuberculosis (MTB). The relation of tuberculin skin test (TST) size, an accepted marker of MTB infection and the frequency of allergic disease symptoms has not been reported from an area where MTB infection is endemic. Objective To investigate the association of TST and allergic disease symptoms, in children living in a tuberculosis (TB) endemic area. Methods In this cross-sectional study, 841 children aged 6–14 years from randomly selected household addresses in two poor communities of Cape Town, South Africa, were investigated with TST and standardized International Study on Asthma and Allergies in Childhood-based questionnaire on allergic disease symptoms. Results Children with positive TST (⩾10 mm) were significantly less likely to have allergic disease symptoms, in particular allergic rhinitis (AR) (adjusted odds ratio 0.43; 95% confidence interval 0.24–0.79) than those with negative TST. This association remained significant after adjusting for possible confounders and correcting for the effect of clustering (>1 child per household address) in the sample. There was a significant inverse linear trend in the relation of TST size in millimetre and the frequency of allergic disease symptoms, in particular AR ( P<0.001). Conclusions These results of inverse association of strong TST reaction and allergic disease symptoms in children from a TB endemic area are in support of the hypotheses that allergic inflammation may be inhibited by chronic infections, such as MTB. [ABSTRACT FROM AUTHOR]