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9/15

A TB cluster in a recent migrant community

A number of TB cases were identified in the Midlands and North of England over an 8 year period.

The majority of the cases were in members of a closely linked recent immigrant community in this region – their country of origin has a high incidence of TB.

  • What do you think are the advantages of using genomics as an epidemiological tool in this situation?

  • Are there any disadvantages? If so – what?

Take some time to think through your answers before checking them.

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What do you think are the advantages of using genomics as an epidemiological tool in this situation?

Genomics would provide a high level of discrimination between strains and could identify closely related isolates (those with few SNPs between them). Together with other epidemiological information, this may identify transmission networks.

Genomics also has the potential to rule out transmission between individuals whose TB isolates differ by a large number of SNPs – in this immigrant community this may help to target resources and prevent unnecessary investigations. Being able to target investigations more appropriately has many advantages, in addition to allowing better use of resources, it may help to build confidence in TB and other health services in communities where this is sometimes difficult to achieve.

Are there any disadvantages? If so – what?

One possible disadvantage of this approach is that if isolates are found to differ by between 5 and 12 SNPs, the probability of transmission is unclear and further epidemiological investigations may be required. However, as more TB genomes from possible clusters are sequenced evidence around this level of genome variation will become more robust.

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