Medical Fun Facts Podcast

MFF0035: Consumption

If I’ve timed this correctly, tonight’s show is dropping on Monday 30 January 2017 and I’m currently in India as the show becomes available. I’m in Delhi for work. I’m attending a World Health Organization meeting on poliovirus containment.

Tonight’s episode is about something beginning with the letter T. So why have I mentioned Consumption? No, I’m not interested in a consumption tax. And no; this is not a show about consuming food, although if you go and visit my food blog at you’ll come across lots to consume.

No, tonight’s show is about tuberculosis. TB used to be called consumption because of the significant weight loss patients experienced. It was like the disease was consuming the patient. TB was also called the white plague (as opposed to the black plague) because of the extreme pallor of the patients. In patients whose disease progressed rapidly, they were said to be suffering from galloping consumption.

I’ve referred to TB in previous shows. TB is a good example for differentiating between infection and disease in episode 6 and when the letter G came up in episode 21. Ghon as in Ghon focus was the centre of attention.

Almost like Syphilis in episode 34, tuberculosis is another ancient disease of medicine.

Deaths from TB are significant. More than one million people every year die from TB. More than 10 million people have TB. As you can imagine the burden is largest in developing countries. Recent advances in diagnosis and treatment have seen many millions of lives saved.

Mycobacterium tuberculosis is a slow-growing bacterium. Its thick waxy cell wall is also protective. These features make TB difficult to diagnose and difficult to treat. Latent infection is the norm. Many people have TB infection but do not yet demonstrate symptoms of the disease. In such people, a sputum specimen is rarely going to produce acid-fast bacilli so other indirect methods are necessary for a diagnosis. In this situation, interferon-gamma IFNγ is measured in plasma after whole blood is collected and stimulated with mitogens. This lymphocyte stimulation assay is a measure of cell-mediated immunity. The IFNγ is elaborated by effector T-cell lymphocytes that have immunological memory to specific antigens. When these effector T cells are stimulated in whole blood they respond quickly and elaborate cytokines including IFNγ. The measurement of IFNγ and the quantification can provide valuable clinically relevant information. Testing for latent infection has become important for patients about to undergo therapy using immunosuppressive drugs. In patients with TB infection, depressing the immune system can reactivate the infection so that such patients develop TB disease.

Unlike many other bacterial infections, TB needs to be treated with multiple antimicrobials. TB is a special situation and has been studied extensively over decades with ample evidence to demonstrate persistent infection and the value of multiple long-term antimicrobials.

Unfortunately, we are now seeing antimicrobial resistance in Mycobacterium tuberculosis so much so that there are some strains resistant to almost all known TB medication. Because travel has become cheaper and easier, people with multi-drug resistant and extensively drug-resistant TB are moving around the globe. This is partially why, when people wish to emigrate and move to another country, receiving countries often have quite stringent testing protocols in place to determine if a potential immigrant is a risk to the population.

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