This World TB Day 2017 theme is: Unite to End TB; Leave no one behind. Many people infected with TB find themselves discriminated against because of their illness. Others are scared to seek treatment because they fear intolerance, whether that be because of their race, gender, religion or their status as migrants and refugees. We can only end TB if these patients can access treatment.
Mario Raviglione, Director of the Global Tuberculosis Programme at the World Health Organization (WHO), notes that “TB is a classical disease of poverty, of the marginalised, of the discriminated against.” This year’s World TB Day theme was chosen to address the plight of those who are scared of the social repercussions of seeking treatment. He adds that only with education will social taboos around TB be eradicated.
This message is especially poignant since TB is one of the top ten causes of death worldwide. Shockingly, 60% of TB cases occur in just six countries: one of those being South Africa. TB preys on those with weakened immune systems, so it is no surprise that it is the biggest killer of HIV-positive people. In 2015, TB was responsible for 35% of HIV-related deaths. (1)

Whilst TB control is successful in many countries around the world, there are still millions of people left behind: still getting infected and not getting treatment. In fact, if you count the number of TB cases in the UK, the USA, Canada and France the total is still less than the number of TB cases in the city of Cape Town.
Robin Wood, CEO of the Desmond Tutu HIV Foundation (DTHF), believes that TB can only be eradicated by “stopping people from being infected with TB in the first place.” Treatment is, of course, important, but TB is highly infectious. A newly infected person will exhale the bacteria into the air and infect others well before getting symptoms themselves. Wood highlights two requirements to prevent new infections: a well-ventilated environment and reducing cases of TB in the local community.
These issues are crucial for the people that this World TB Day hopes to raise awareness for refugees, those in poverty, and those who are discriminated against. Groups who typically live in overpopulated areas or struggle to access treatment.
Preventing new infections is not simple, but DTHF has embarked on research and outreach, taking us closer to a TB-free world.

Our Research

Carl Morrow, Principal Scientific Officer at DTHF Medical Research Council (MRC) Flagship Project, notes that one of the biggest barriers to TB eradication is that scientists don’t fully understand the transmission of the disease. It is straightforward to gather sputum samples and grow the TB bacteria in a petri dish. In contrast, it is very tricky to collect samples of exhaled air from a patient. Considering that rebreathed air is the main culprit for transmission, it is imperative to study it to understand the disease. However, it was widely deemed to be an impossible feat; the concentrations of bacteria in the breath too tiny to see. Like a grain of salt in a sand pit.

Fortunately, great science starts with the word ‘impossible’. Morrow is happy to say that “we have done the impossible” and measured the concentration of TB in exhaled air. You can count the number of TB bacteria in one litre of air with one hand: 5 microbes. Whilst five microbes in one litre of air might seem like a small amount, it is a much larger concentration than was predicted.
The MRC Flagship project has made huge experimental bounds: refining methods for capturing exhaled air, quantifying the number of TB bacteria in an air sample and characterising the genes of the TB microbes in those samples. This groundbreaking research is far from over. The next stage is to determine how the mechanisms in those airborne TB microbes make them so infectious.

TB Transmission Risk in the Community

The first step in creating successful TB prevention strategies is to figure out in what sort of environments the microbe thrives. DTHF has been measuring the possibility of catching TB by using measurements of carbon dioxide (CO₂) in the environment. When we breathe, we inhale air to use oxygen and then exhale CO₂. The air outside has relatively low levels of CO₂ because the wind carries exhaled air up into the atmosphere. However, if a person sits in a room with all the windows and doors shut, it will have higher levels of CO₂ as they rebreathe the same air. The amount of CO₂ in the air is different in your home, on a bus, at school or in the office. The more carbon dioxide in the room, the more air you share with others and the greater the risk of transmitting TB.

To get a sense of how likely it is a that a child may contract TB at a school in Cape Town, DTHF gave a pupil a CO₂ monitor. It tracked the changes in CO₂ in the atmosphere as they went about their school day (3). Morrow points out that they measured “a potential transmission risk, not an actual transmission risk” since the CO₂ monitor is unable to gauge the amount of TB in the air, just the amount that could be shared.
There are two areas where the amount of rebreathed CO₂ were significantly higher than the rest of the school: regions E and F. Wood explains that these two classrooms only had windows on one side of the room. This reduces the air flow and the students rebreathed more air which increases the risk of new TB infections.
Wood commented how modern buildings aren’t always designed with health in mind. “High ceilings are good, but schools are now overcrowded, and they put them into low-ceiling modern, buildings and don’t ventilate them.” He highlights that architecture with health in mind would be a big step in combating TB.
To watch Robin Wood’s public lecture on TB transmission in Cape Town, recorded at the Steve Lawn Memorial Inaugural Lecture, please click here.

The Tutu Tester  – Taking Treatment to the Community

Alongside research into tuberculosis, DTHF also provides outreach services. In Cape Town, there are communities where treatment for TB is hard to find. So, the Tutu Tester and the Tutu Teen  Truck, rainbow-coloured clinics-on-wheels, take essential medical facilities straight to these communities.

Since they began, the Tutu Tester has seen over 6,000 patients and the Teen Truck, solely for adolescents, has seen nearly 4,000. What is remarkable about their patients is the unprecedented engagement with young men when compared to traditional clinics. This indicates the success of mobile clinics in reaching difficult-to-reach populations.

“These people don’t come in on their own steam, so we take the service to them,” comments Philip Smith, the mobile services programme manager. He explains that in areas of poverty there aren’t enough medical facilities which results in overcrowding and long waiting times. 

The Tutu fleet is equipped with a specialist, rapid-testing TB machine called GeneXpert. This is a point-of-care diagnostic machine for TB and drastically reduces waiting times for a TB status diagnosis. This tool can hopefully increase access to medication and care.

The fight to end TB doesn’t end on World TB Day. 

Stopping TB will be a challenge, but the end is in sight. The Desmond Tutu HIV Foundation will continue to research TB and provide outreach for those most in need.
Even with momentum building, there is still need to raise awareness for this disease. If you feel like joining the ‘fight’ to end TB, please consider donating to the Desmond Tutu HIV Foundation here. Additionally, you could contribute to the Steve Lawn Memorial Fund, to continue his work researching tuberculosis.
You can also tweet us and show your support by using the hashtags #EndTB and #WTBD2017.
We can unite to end TB.
 
References:

1. Tuberculosis Fact Sheet 2016. World Health Organisation. [Online] available: http://www.who.int/mediacentre/factsheets/fs104/en/ 
2. Tuberculosis 2016 report. World Health Organisation. [Online] available: http://www.who.int/tb/publications/global_report/en/
3. Richardson ET, Morrow CD, Kalil DB, Bekker LG, Wood R. Shared Air: A Renewed Focus on Ventilation for the Prevention of Tuberculosis Transmission. PLoS One. 2014; 9(5): e96334. [Online] available https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4012987/
4. Scanning Electron  Microscopic image of Tuberculosis. Public Health Image Library. [Online] available: https://phil.cdc.gov/phil/details.asp?pid=8438

 
Written by Caroline Reid