Skip to main content

Increasing awareness about latent tuberculosis infection

The BSI recently funded a Communicating Immunology Grant to BSI member Alice Halliday to produce a film about tuberculosis (TB). Here, Alice tells us more about the global issues surrounding TB and the work her team are doing to improve knowledge and awareness around this issue in London communities. 

Tuberculosis (TB) is a global problem, and is currently the leading infectious killer worldwide. The infectious cause, the bacterium Mycobacterium tuberculosis, has existed and evolved alongside humans since we first migrated out of Africa 70,000 years ago. Perhaps due to this close evolutionary relationship, the bacterium is arguably the most successful human pathogen, and is estimated to infect up to a third of the global population. It is particularly skilled in avoiding attack by the immune system, living and replicating inside cells which are normally proficient in killing microbes: macrophages. It is also able to avoid killing by host T cells, which, while mounting a measurable and seemingly ‘appropriate’ response to the bacteria, are rendered unable to reach all of the bacteria at the site of infection and kill them.

In most infected individuals, the bacteria and the immune system reach a kind of truce: the bacteria exist in low numbers within macrophages inside the body tissue (usually the lungs), and the immune system prevents them from multiplying, spreading, and causing harm. This state of truce is known as latent TB infection, and in the vast majority of people this is considered a healthy state with low risk of developing to disease. However, sometimes an individual’s immune system can lose control of the bacteria, and they can begin to multiply exponentially within the body and cause active disease, which can be deadly if untreated.


The burden of TB

On the global scale, the areas of the world with the highest burden of TB are countries in Sub-Saharan Africa, the Indian subcontinent and South-East Asia. However, there are pockets of high TB incidence all over the world. Within Europe, England has one of the highest rates of TB, with 5,758 cases reported in 2015. Approximately 40 % of these cases were within the London area. As in other western countries, many of these new TB cases are cases of progression from latent TB infection, particularly within non-UK born populations who have previously lived in areas of high TB incidence.

As latent TB infection represents a large reservoir of potential active disease, the World Health Organisation now recommends targeted screening of all individuals who have recently arrived from high endemic areas. In 2015, Public Health England and the NHS launched a new collaborative strategy for Tuberculosis, which includes a latent TB screening programme targeted for new entrants from high endemic countries. By finding more cases of latent TB and providing these people with preventative treatment, it is predicted that the rates of new TB disease cases in England will fall.

There are many barriers to the success of the latent TB screening programme, including a lack of awareness about latent TB, a lack of engagement with primary care services amongst migrant communities, and stigma associated with TB disease.  As few as 30% of new entrants eligible for screening register with a GP within the first 5 years of arriving to the country.


Developing the film

The animation team presenting the video at Imperial Festival

To raise awareness about latent TB, and to encourage people to engage with their GPs to get tested, our team of scientists from the TB Research Centre at Imperial College London developed an animation about latent TB infection, with support from the BSI Communicating Immunology Award. Additional support was provided by the NIHR HPRU in Respiratory Infections. Our team of three: Alice Halliday (a post-doctoral immunologist), Ishita Marwah (a clinical research fellow) and Mica Tolosa-Wright (a research technician), developed a short script and animation outline. The film focuses on what latent TB infection is and how the immune system plays a role in the outcome of infection. We worked with an animation studio, Alternative View Studios, who developed the outline script into a professional 2-minute animation with a voice-over. Throughout the process, our team worked with other Imperial College members of staff who work directly with latent TB patients and the screening programme.


First film screening

The final version of the film was ready  at the end of April 2017 and was screened to hundreds of members of the public at the Imperial Festival in early May. The film-making team used this opportunity to seek feedback and evaluation of the film from 182 people. Of those who completed the evaluation, only 39% had heard of latent TB infection before watching the film. After watching the film, 85% correctly identified the percentage of the global population that has latent TB infection – which is 33%. Over 90% of the respondents found the film to be either crystal clear, or mostly clear. The respondents also answered questions to found out what they had learned about how active TB is transmitted. The initial results of the evaluation of these data are encouraging, but a full evaluation with the target audience is now required to ascertain whether the film will have a positive impact on engagement with the latent TB screening programme.

In the coming months, we will run a focus group and evaluation session with individuals who are eligible for latent TB screening in Tower Hamlets.  We have also gained additional funds to translate the film into several key languages spoken by the target audience of new entrants. Meanwhile, talks are underway to show the film in GP clinics in areas around London that have the highest rates of TB. The team involved, usually based entirely in the lab, has found the whole experience exciting and rewarding. The film is now publicly available, and will help build awareness about what latent TB is. As said in the film: “TB is preventable and curable” and we hope that by spreading this message and empowering people to seek testing and treatment, we can start to win the battle against this important disease.

Alice Halliday

Research Associate, TB Research Centre and HPRU in Respiratory Infections

National Heart and Lung Institute, Imperial College London

You can read more about TB and the work of the team in this Imperial Medicine blog