Guest blog for World TB Day

We have a guest blog from Dr Jessica Potter and Dr Adrienne Milner to mark World Tuberculosis (TB) Day.

Introduction

The 24^th March each year marks World TB Day – the date in 1882 on which Dr Robert Koch presented his famous paper that demonstrated that tuberculosis (TB) was not an inherited disease as some thought ¹ but rather caused by a bacterium – Mycobacterium tuberculosis.

In the 21^st century, despite being completely treatable, TB remains a disease of the marginalised, thriving in spaces where human rights have not been realised.  Some have argued ^1,2 that with an increased understanding of how TB is spread and the medicalisation of its treatment, strategies to rid the world of TB focus too heavily on control and surveillance, with underinvestment in mechanisms to improve the wider social and political determinants of TB ³.

Social Determinants of TB

TB has long been associated with poverty ^4–6 and conditions associated with poverty such as overcrowding, poor nutrition and lack of access to appropriate health services.  It was improvements in these ‘social determinants of health’ ⁷ that were responsible for the steady decline in mortality from TB in the early 1900s, well before the advent of effective antibiotic treatment in the mid 20^th century.

By 1993 however, fuelled by the HIV epidemic and globalisation amongst other factors ⁸, TB was declared a global emergency ⁹. In high-income, low-TB burden countries the distribution of disease shifted with most cases occurring amongst migrants.

Particular health challenges are encountered throughout the migratory journey ¹⁰ and these differentially affect disease risk ¹¹.   The ‘healthy migrant effect’ describes the fact that most migrants arrive at their destination in good health ^12,13. However, this advantage deteriorates after arrival ¹⁴.  This is likely to occur because of stresses that accompany the experience of being a migrant such as those associated with the acculturation process ¹⁵, language barriers, employment struggles and lack of social support (Wilkinson & marmot 2003).  In the case of TB, both direct transmission of active disease or reactivation of latent TB may be facilitated by the particular stressors and environmental conditions experienced during ¹⁶ and after the migration process ¹⁷.  Thus migration in and of itself has recently been labelled as a social determinant of health ^18–20.

TB in the UK

In 2016 there were 5,664 cases of TB in the UK, 74% among the non UK-born population ²¹.  Countries of origin amongst foreign-born patients reflect both migrant flows and the global distribution of TB, with the highest numbers of cases amongst people from South Asia and Sub-Saharan Africa (ibid). Evidence suggests these cases occur largely as a result of reactivation of latent infection originally acquired abroad rather than through recent transmission ^22,23.

TB control strategies in the UK centre around three key principles: early diagnosis, effective treatment and preventative treatment for those at high risk (including both treatment for LTBI and vaccination) (WHO). In 2015 Public Health England and NHS England launched the joint national tuberculosis strategy with an aim of achieving a year on year reduction in TB incidence.  The strategy highlights ten key areas for improvement including: access to services and early diagnosis; comprehensive contact tracing; improved BCG vaccination uptake; tackling TB in underserved populations; and the new entrant screening programme which is the only area to come with additional financial support.

The impact of the hostile environment

Over the past 5 years successive governments have employed techniques to create a ‘hostile environment’ for those living in the UK illegally. These strategies include restricting access to services that have an effect on a range of the social determinants of health for migrants and in particular are detrimental to TB control efforts.  For example, overcrowding is a known risk factor for TB transmission. However, policies that restrict access for vulnerable migrants such as the ‘right to rent’ checks force vulnerable migrants into low budget, poorly maintained and often over-crowded accommodation.

As part of the NHS Visitor and Migrant Cost Recovery Programme, on 23^rd October 2017, upfront charging was introduced for those ineligible for free NHS care requiring non-urgent treatment.  Whilst TB is exempt from such charges, routes to diagnosis are often circuitous ²⁴, and patients are not always aware of their rights ²⁴.  Further, to determine eligibility, identification documents are required.  This process may not only deter those fearful of deportation from seeking healthcare ²5 but also those who do not have a passport such as the homeless or the elderly ²⁶. In fact, a recent study of over 2000 TB cases showed evidence of a significant association between the roll out of the Visitor and Migrant Cost Recovery Programme and worsening delays in diagnosis amongst the non-UK born population across three boroughs in a high burden setting in London ²⁷.

Conclusion

While the national TB strategy has laudable goals, its implementation is being challenged by anti-immigrant government policies that construct ‘adverse conditions of care’ ²⁸ for migrant TB patients in the UK. Although the risk of TB to the general public is currently low, diagnostic delay threatens the health and life of individuals infected with TB as well as heightens the exposure risk of others to the disease. We must challenge policies that restrict healthcare access to some of the most vulnerable in society.  Without doing so, we cannot hope to continue the downward trend in TB incidence experienced in recent years and eradication will have to wait for another century.

References

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