Introduction

Worldwide, tuberculosis (TB) causes 1.3 million deaths each year, and there are at least 9.27 million new cases annually.1 Global population mobility on a scale never seen before means that the UK, along with many other countries with a previously low incidence of the disease, has over the last two decades seen a sharp rise in TB. Indeed most doctors are probably more likely to see a case of TB in the next year than at any other time in their professional lives. In the UK, there are now in excess of 8400 new cases per annum, >70% of them occurring in individuals born outside the country,2 and the picture is similar in the USA, where over half of all cases occur in those born abroad.3 The annual UK rate of TB for those born abroad (87/100 000) is >20 times higher than that for the UK-born population (including UK-born members of ethnic minority groups). For the Black African population in the UK who were born outside this country the rate (at 309/100 000) is 75 times higher than in the UK-born population generally, reflecting the very high TB rates associated with HIV co-infection in sub-Saharan Africa.2

Clearly, current methods of TB screening for new entrants, largely for active TB only, are not working, and debate about how they might be improved has spread beyond health professionals to become the focus of media comment, often hostile, and the subject of political attention and debate.4 We discuss the limitations of current UK screening methods, suggest that the natural history of infection with the TB bacterium means that they cannot succeed and consider alternative approaches.