24 March is World Tuberculosis Day. Tuberculosis is curable and preventable – yet 1.8 million people died as a result of it in 2015 alone, meaning it ranks alongside HIV as the world’s most deadly infectious disease. This graphic take a look at the basics of the disease, and how it can be treated.
Tuberculosis (TB) is an odd disease in that many people contract it without showing any symptoms or experiencing ill effects. This is known as latent tuberculosis, and it’s estimated that one third of the world’s population is infected. People with latent tuberculosis cannot transmit the disease to others, but it can progress to active tuberculosis in around 10% of cases. Left untreated, active tuberculosis kills around half of those infected.
Tuberculosis occurs worldwide, but the greatest number of deaths occur in developing countries. Just six countries accounted for 60% of new tuberculosis cases in 2015: India, Indonesia, China, Nigeria, Pakistan, and South Africa. People suffering from HIV are particularly susceptible, and lifestyle factors such as smoking can also increase a person’s risk of developing active TB.
Treating tuberculosis is challenging because the bacteria that cause it divide much more slowly than most bacteria, taking around 15-20 hours to do so. As many antibiotics target bacterial cell division, this can make the TB bacteria take much longer to wipe out. In addition the bacteria have a unique cell wall containing waxes formed from mycolic acids which render many antibiotics ineffective.
As a consequence, TB treatment is not a quick and easy fix. It requires a regime of four front line antibiotics over a period of several months to wipe out the infection completely. Worse, resistance to one or more of these antibiotics is becoming more common, requiring second line drugs which can be less effective or have toxic side-effects to be used.
World Tuberculosis Day aims to raise awareness of the fact that tuberculosis is still an epidemic in many parts of the world. The World Health Organisation has set a target of reducing the number of deaths worldwide by 95% by 2035, and in order for this to happen new drugs to tackle the disease will be crucial. You can see progress on new treatments at the Stop TB Partnership’s site, and there’s more on the aims of World Tuberculosis Day from the World Health Organisation.
Thanks to Dr. Elizabeth Fullam of the University of Warwick for the suggestion for this graphic.
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References & Further Reading
- Tuberculosis – Centers for Disease Control and Prevention
- Treatment of tuberculosis disease – Centers for Disease Control and Prevention
- Pathophysiological implications of cell envelope structure in Myobacterium tuberculosis and related taxa – D E Minnikin and others
- Advances in the development of new tuberculosis drugs and treatment regimens (£) – A Zumla and others