Epidemiology

Tracking a TB Network

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Science  25 Mar 2011:
Vol. 331, Issue 6024, pp. 1493
DOI: 10.1126/science.331.6024.1493-b

Improvements in two very different methods of investigation led to better understanding of the dynamics of a tuberculosis (TB) outbreak in British Columbia, Canada. A 10-fold increase in TB cases was reported in a Canadian community between 2006 and 2008. Initial genotyping analysis by Gardy et al. suggested that the outbreak was clonal; however, whole-genome sequencing of M. tuberculosis isolates produced a different picture: The cases were the result of two outbreaks. Examination of historical isolates indicated that the two lineages were present before the recent outbreak, which suggested that it was a social or environmental effect, not a genetic mutation, which triggered the increase in cases. Social network analysis was then used to build a picture of risk behavior, interactions, and social meeting places. When this was combined with the whole-genome data, the investigators were able to identify sources of the outbreak and a likely contribution of increased crack cocaine use. As sequencing costs go down and network analyses become more sophisticated, it is likely that these strategies will be increasingly used in public health efforts.

N. Engl. J. Med. 364, 730 (2011).

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