Research news: April 2011
N Engl J Med2011;364:730-9
After traditional contact tracing failed to find the source of an outbreak of tuberculosis in a community in British Columbia, whole genome sequencing and social network analysis were used and proved superior to standard epidemiological methods. At first, it seemed that all 41 cases of tuberculosis stemmed from a single index patient, given that initial genotyping suggested the outbreak was clonal. However, a whole genome analysis of Mycobacterium specimens revealed two distinct lineages of M tuberculosis among the infected people, suggesting that two simultaneous outbreaks had occurred.
A social network approach was used to improve identification of key people, places, and behaviours that contributed to the spread of the outbreak. This enabled the researchers to learn that many respondents had transient living arrangements, nearly two thirds used crack cocaine and misused alcohol, and many frequented specific locations—including two hotels, meal and community centres, and several crack