Tuberculosis screening

Tuberculosis (TB) screening and early detection methods, for professionals working with at-risk populations in the UK.

The onset of tuberculosis (TB) can be insidious, and early stages can be difficult to detect. This can lead to diagnostic delays. Almost all forms of TB are treatable and curable, but delays in detection and treatment can result in less favourable outcomes for the individual and possible spread to other people.

Screening can be defined in many ways. The UK National Screening Committee is responsible for population screening and runs the national NHS screening programmes. It defines screening as a ‘process of identifying apparently healthy people who are at increased risk of a disease or condition’.

There are different types of screening for TB, including those aimed at detecting latent TB infection (LTBI) in people without symptoms, and those aiming to detect early active TB disease. These TB screening initiatives are not currently overseen by the UK National Screening Committee, however, LTBI screening is recommended by NICE for people at higher risk of TB.

There are also efforts to detect the most infectious forms of TB at the earliest possibility, by raising awareness among professionals and the public, or through active case finding of TB affecting the lungs. Awareness raising, LTBI screening and active case finding support each other as public health activities.

TB active case finding

Active case finding (ACF) is a strategy to identify and treat people with TB who would otherwise not seek prompt medical care (Golub et al, 2005), targeting high-risk groups. Detecting TB early allows early treatment initiation and prevents further spread.

Active case finding usually focuses on detecting of pulmonary TB using chest X-rays or performing a symptom enquiry.

Upon finding abnormal results, further tests can follow, such as the collection of the patients’ sputum. ACF has been widely used among risk groups in low incidence countries.

In the UK, ACF is performed among the following groups:

  • professionals at risk of TB (eg healthcare workers)
  • close contacts of patients with TB (if active TB is suspected)
  • people with social risk factors such as

    • homeless people
    • people with drug and/or alcohol problems
    • prisoners
    • immigrants from countries were TB is common

TB awareness raising

Tuberculosis occurs in many different forms, the onset of TB is not always clear, and the typical symptoms do not always appear.

TB awareness raising makes healthcare professionals and members of the public more alert to the epidemiology and clinical manifestations of TB.

Maintaining increased awareness of TB among health professionals, high-risk groups and people who work with them, teachers and the public is very important. This can be done through various activities such as the production of information and educational materials about TB in various formats and languages, using various forms of media, community groups and training.

In the UK, several organisations are involved with awareness raising activities including TB Alert and the National Knowledge Service.

Latent TB infection (LTBI)

In 2014, the WHO estimated 9.6 million new TB cases and 1.5 million TB deaths worldwide (WHO global tuberculosis report 2015.

Compared to other European countries, the incidence of tuberculosis in the UK has remained high. Most cases in the UK occur among individuals who were born or spend considerable time in a country where TB is very common. It is likely that the majority of TB cases in the UK are the result of ‘reactivation’ of latent TB infection (LTBI), an asymptomatic phase of TB, which can last for years.

Screening tests for LTBI are available:

It is not feasible or cost-effective to screen an entire population for LTBI but screening for specific groups at high risk in the UK is recommended by the National Institute for Health and Care Excellence (NICE). These groups include:

  • close contacts of patients with TB
  • healthcare workers
  • immunosuppressed patients (e.g. those with HIV)
  • migrants from countries where TB is common

There is good evidence that LTBI screening for people arriving from areas with a TB incidence of 150/100,000 or more is cost effective for the NHS.

In keeping with NICE guidance, successful local LTBI screening pilots have been carried out by local authorities and primary care trusts, but the coordination and targeting of these screening activities in the past was not ideal. As a result, the Collaborative TB Strategy for England 2015 to 2020 recommends systematic LTBI testing and treatment for 16 to 35 year olds who recently arrived in the UK from high incidence countries (WHO TB rates of 150/100,000 or over and Sub-Saharan Africa) as a key strategy intervention. New NHS funding has been made available to support the implementation of a systematic LTBI testing and treatment programme in England.

A number of documents have been developed to support the implementation of LTBI testing and treatment in England:

See NHS England’s collaborative TB strategy FAQs on commissioning, data returns, information governance and communications.

Watch a short film where Dominik Zenner summarises the national LBTI testing and treatment programme, courtesy Camden GP CCG.

National surveillance and data reporting system for LTBI testing and treatment has been approved by the PHE Caldicott Guardian and Chief Knowledge Officer as well as other national and local information governance leads. Data transfer and storage strictly adheres to PHE and NHS guidelines and policies, to the highest level of information governance standards. The legal ability for PHE to collect patient identifiable data is based in regulation 3 of section 251 (National Health Service Act 2006).

The act comes with the obligation to communicate to patients how their information is processed and utilised (‘Fair processing notice’), which is included in the LTBI testing and treatment patient information leaflet.

Pre-entry TB screening for migrants

Since the late 1960s, UK border control agencies have required migrants to have a medical examination at the ports of entry into the UK. Chest x-rays were introduced at London’s Heathrow and Gatwick airports to ‘screen’ for active TB of the lungs (pulmonary TB). However, this method was not effective at identifying latent TB infection (LTBI).

From May 2012, the Home Office replaced the system of active TB case finding at ports with ‘pre-entry TB screening’ prior to migrants applying for a visa to enter the UK. A systematic review of pre-entry screening programmes was conducted by Aldridge et al.

Everyone who applies for a UK visa for more than 6 months and who is resident in a country where TB is common (over 40/100,000), will be screened for pulmonary TB at one of the UK approved TB screening centres.

Visa applications can only be processed once the applicant has been issued with a certificate of clearance to show they’re free from active pulmonary TB. A map of the screening providers is available.

Instructions on pre-entry TB screening for the UK are the UK rules for pre-entry TB screening.

The TB screening for the UK patient information leaflet provides information about the screening process. All providers screening for the UK are subject to UK quality assurance. Public Health England collaborates closely with the Home Office to support the development of Quality Assurance (QA) systems to ensure that the pre-entry TB screening programme is “fit for purpose” in delivering its stated objectives.

The UK collaborates with a number of other countries (Australia, Canada, New Zealand and the USA) in the pre-entry screening. Most of these countries have used a pre-entry screening system for many years and have considerable experience with such a system.

Pre-entry TB screening will contribute to reducing the scale of the problem of active TB in the UK. However, many of the new cases in the UK are due to latent TB, which can become active after several years. Pre-entry screening can only detect TB among people with active pulmonary disease at the time of screening.

UK pre-entry tuberculosis screening reports.