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.