Investigation of an ongoing cluster of tuberculosis (TB) associated with prisons, England

Prisons are high-risk environments for the spread of tuberculosis (TB).We investigated an ongoing prison-associated TB cluster to identify common exposures.We defined cases as residents in England with laboratory confirmed TB belonging to the genetic cluster.We extracted records from the national TB surveillance system, linked to prison operational data, and conducted descriptive analysis of demographic, clinical, and phylogenetic data.Years were masked for anonymity.Over six years, 12 individuals were identified, predominantly male (83%) and median age 34 years, in London, East Midlands, and East of England.Prison history was noted for 7/12 (58%) at 13 prisons.Everyone without prison history completed treatment, but 2/7 with prison history were lost to follow-up and 5/7 were still in treatment or outcome not evaluated.We identified frequent prison transfers and concurrent stays of four individuals at Prison B, and two at Prison G. Phylogenetic analysis indicated distinct sub-clusters with and without prison history, suggesting expansion of the cluster from community into prisons.Prisons continue to play a role in TB in England.Factors such as frequency of transfers could hinder treatment completion and control of transmission.Combining phylogenetic, epidemiological, and prison operational data facilitated investigation of transmission pathways.