Tuberculosis: The Forgotten Pandemic
In our Zoom for Thought on February 23rd, 2021, UCD Discovery Director Prof. Patricia Maguire spoke to Stephen Gordon, Professor at UCD School of Veterinary Medicine, about “Tuberculosis: The Forgotten Pandemic”. In case you missed it, here are our Top Takeaway Thoughts.
A Brief History of TB
Tuberculosis (TB) is a bacterial lung disease which infects both humans and animals. The bacterial causative agent was discovered in the 1880s by Robert Koch. The TB vaccine BCG is one of the most widely used in the world, with 150 million doses given annually. Despite also having antibiotics and drugs to treat it, TB is still one of the most lethal infectious diseases globally. There are 10 million new cases of active TB in humans annually, leading to about 1.5 million deaths - or a death every 20 to 25 seconds.
COVID-19 and TB
The COVID-19 pandemic has understandably seen a transfer of resources away from control of TB towards control of COVID-19. Because of this, case detection rates for TB are falling, along with our ability to control the disease. Both COVID-19 and TB are lung diseases whose outcomes rely on access to healthcare and are therefore impacted by poverty. “Can we stop the transmission chain? That's the overarching driver.” Most cases of TB are found in India, Africa, Southeast Asia and the Western Pacific.
One Health
The COVID-19 pandemic has increased public awareness of zoonotic transmission - infection that moves from animals to humans. It has brought attention to the idea of One Health, which looks at the interaction between human, animal and environmental health. Interdisciplinary research is at the heart of One Health. “You really do need a vast array of expertise,” says Gordon, a molecular bacteriologist. “You need expertise from veterinarians, human medics, expertise in wildlife surveillance. A huge amount of expertise needs to be brought to bear on this issue to really try and make an impact in terms of disease control.”
TB Anti-vaxxers
Global rollout of the BCG vaccine ramped up after World War II - and there were anti-vaxxers back then too. In India the anti-vaccine movement centred around the ongoing need to improve equality of access to healthcare generally. The idea that “simply layering in a vaccine on top of that may not be enough was a big debate that went on there”.
No BCG in Ireland
Until 2015 Irish newborn babies routinely had a BCG vaccine. But given the TB incidence rates in Ireland are about five per 100,000 - and that BCG vaccines are in high demand worldwide - the issue arose about whether we should “be using these vaccines if they are in short supply”. Some 150 million neonates worldwide get the BCG vaccine every year through the World Health Organization’s Expanded Programme on Immunization (EPI).
Eradication Challenge
TB is a chronic infection, about a quarter of the world’s population is infected who have a 5-10% lifetime risk of developing active TB. You can be infected but not necessarily progress to disease. Comorbidities like HIV coinfection, malnutrition, smoking and diabetes can accelerate progression to disease, making it a 5-10% annual risk of disease if infected. “TB is an infection that can persist latently inside us over a very long period of time - only breaking down to active disease at a later date - and that makes it difficult to think about how we could eradicate it globally. It's an incredibly well adapted pathogen to us in terms of its ability to infect and persist until the right moment to cause active disease. The weight of infection globally is enormous because of that.”
Remembering Pandemics
It is “absolutely critical” that we remember the current pandemic “in terms of the mobilisation of expertise and research to tackle COVID-19”. We need to be able to sustain this knowledge “not only for the next pandemic, not only for TB, but for other issues like antimicrobial resistance or things like climate change. All of these issues require multidisciplinary interactions and new ways of thinking”.