The largest prison outbreak of TB in Western Europe investigated using whole-genome sequencing

BACKGROUND: In March 2011, the Department of Public Health East in Ireland were notified of two cases of TB in two prisoners sharing a cell. We define the resulting outbreak and highlight the role of public health and laboratory-based molecular epidemiology in map- ping and control of a prison outbreak. METHODS: Cases were identified through clinical pre- sentation, contact tracing, case-finding exercise or enhanced laboratory surveillance. Mycobacterium tu- berculosis isolates were genotyped and underwent whole-genome sequencing (WGS). RESULTS: Of the 34 cases of TB linked to the outbreak, 27 were prisoners (79%), 4 prison officers (12%) and 3 community cases (9%). M. tuberculosis was isolated from 31 cases (culture positivity: 91%). A maximum of six single-nucleotide polymorphisms separated the isolates, with 22 being identical, suggestive of a highly infectious 'super-spreader' within the prison. Isolates belonged to the Beijing sub-lineage, and were susceptible to first-line anti-TB agents. A case-finding exercise incidentally detected a prisoner with multidrug-resistant TB. Of the 143 prison officers screened, 52% had latent TB infection. Litigation costs exceeded five million euros. CONCLUSION: This constitutes the largest prison outbreak of TB in Western Europe investigated using WGS. A robust prison entry TB screening and education programme is required to effect better TB control, and prevent future outbreaks and attendant litigation.

Automated summary

This study investigated the largest outbreak of TB in a prison in Western Europe, using molecular epidemiology and detection methods to reveal the spread of the epidemic. The presence of a highly infectious "super-spreader" in the prison highlighted the importance of TB control in correctional facilities.