By Rachel Pugh
Tackling latent TB infection in the UK by screening new entrant to the country and use of pre-entrant screening appears to be having an effect on TB rates, which have begun to decrease for the first time in 20 years.
The number of cases of active TB has come down to around 5000 cases per year after the introduction of a national TB strategy, making the UK officially a ‘low incidence country.’ In announcing what he called this ‘good news’, Professor Onn Min Kon, a respiratory physician at Imperial College London, underlined the importance of continuing to focus on latent TB, in order to eradicate active TB.
Pre-entry screening has contributed to the decline by a third of TB between 2011 and 2015. New entrant TB testing and treatment funded by the NHS has a 17 per cent positivity rate and a treatment uptake of 62 per cent of whom 81 per cent complete the course.
But reaching people with the latent disease is a challenge as the WHO has identified them principally as contacts of people with active TB (who can number more than 30), patients awaiting TNF, dialysis and organ transplants and hard-to-reach people such as homeless people, drug addicts and prisoners.
Professor Kon said: “This group cannot just be handled by a TB doctor isolated in a clinic, you will have to talk to many other people to identify social risk factors.” This might involve working with a diversity of groups such as Citizens Advice Bureaux, pharmacies and housing officers.
The use of molecular diagnostics and whole-genome sequencing appear to hold promise in improving the speed of diagnosis and drug resistance compared with conventional smear and culture methodologies. Professor Kon highlighted the Xpert MTB/RIF which is endorsed by WHO and requires no technical expertise to administer and can produce a result within a working day. Whole-genome sequencing has been endorsed by the NHS and offers greater precision about transmission and more targeted contact tracing.
Against the trend of the reduction in TB rates, multi-drug resistant TB continues to be a significant public health concern globally and locally. New drugs are emerging which give hope in this field, especially Bedaquiline, a mycobacterial bactericidal drug, which also kills non-tuberculous mycobacteria.
Professor Kon said recent trials by GSK have raised hopes of a vaccine, the first since the introduction a century ago of the BCG. This showed that M72/AS01E provided 54.0 per cent protection for Mycobacterium tuberculosis-infected adults against active pulmonary tuberculosis disease, without evident safety concerns1, the big news in a slow-moving clinical field.