TB is back with a vengeance

If you were a teenager before 2005, one reminder of tuberculosis in British life is that small circular scar on your bicep. Maybe you’ve explained to your children why it’s there, if you ever knew. The BCG is no longer a routine vaccination in the UK, a revision which signalled to many that TB was over. What used to be known as consumption became treatable, preventable and ostensibly consigned to medical history as a threat of the past.

We tell stories about diseases as if they are constant things. ‘It’s no worse than flu’ has become a familiar phrase; but flu is not all that common, it varies wildly in severity and changes strain every year. Pathogens evolve and mutate, avoiding the risk of staying the same for too long. Despite public familiarity with Covid variants, the idea that the virus is acquiring several new identities – perhaps more infectious or lethal than what’s come before – is unnerving. That an antique bacterial scourge such as TB is also shapeshifting to subvert our biochemical and immunological defences is unthinkable. But true.

Infectious diseases do not replace or make way for each other; they overlap. Lungs hollowed out by TB are a perfect den for coronavirus. Bodies with Aids often die from TB, as HIV patients’ immune systems are weakened beyond resistance. This microbial economy stands in contrast to our divided social and emotional resources. A prominent infectious disease diverts media attention, healthcare budgets and sympathy away from others. Covid has been dominating headlines, but TB has been making quiet inroads for years. Now almost a third of the world’s population is infected. Once transmitted, the bacteria can nestle for decades in a healthy immune system before starting to replicate. In 2020, one and a half million people died from TB.