The White Death: Tuberculosis

Jul 20, 2024

The White Death: Tuberculosis

Introduction

  • Steve (Kurzgesagt narrator) introduces John Green for a special story.
  • The story is about tuberculosis (TB) or the White Death.

Historical Impact

  • TB has haunted humanity for thousands or millions of years.
  • Present during significant human milestones (e.g., taming fire, venturing out of Africa).
  • In 1815, TB caused 1 in 4 deaths in Britain.
  • Over the last 200 years, TB killed 1 billion people - more than all wars and natural disasters combined.
  • TB is still the infectious disease with the highest kill count today.
  • 1 in 4 humans alive are currently infected with TB (Mycobacterium tuberculosis).

The Silent Predator

  • TB is very infectious but often remains quiet, careful not to kill recklessly.
  • Adaptation: Perfectly adapted to the human immune system and difficult to kill.

Infection Mechanism

Entry and Initial Attack

  • TB bacteria enter the body through airways and settle in the lungs.
  • Macrophages: Immune cells that attack and devour TB bacteria, but TB has evolved to resist this.
  • Bacteria modify macrophages, turning them into hosts and consuming them slowly.
  • TB bacteria replicate slowly compared to other microbes.

Formation of Granulomas

  • Immune response is triggered by decaying macrophages, but TB bacteria resist many attacks.
  • Granulomas: Formed by immune cells to contain TB bacteria.
    • Center: Infected and dead macrophages.
    • Surrounding: Immune cells to contain bacteria.
  • Granulomas protect TB from medication and immune attacks, leading to a stalemate.
  • 2 billion people have inactive TB (infection is sleeping).

Active Tuberculosis

  • In 1 in 10 cases, TB becomes active.
  • Symptoms: Difficult breathing, coughing (sometimes blood), fever, weight loss.
  • Inflammation: Immune response causes inflammation in the lungs, leading to damage.
  • Spread: Coughing spreads millions of bacteria to others.
  • Untreated, TB can overtake the body, spreading to other organs and causing death.
  • In 2023, 1.3 million people died from TB.

Challenges in Combating TB

Slow but Deadly Disease

  • TB kills slowly, unlike fast-killing diseases (e.g., COVID-19), making it less alarming.
  • Slow progression often leads to mild symptoms for months, delaying diagnosis and treatment.
  • TB spreads through prolonged close contact (family, friends, coworkers).
  • Crowded and poorly ventilated environments increase transmission.

Antibiotic Resistance

  • TB is curable with a 4-month regimen of antibiotics.
  • Antibiotic Era: Significant progress between 1940 and 1965, followed by a decline in new drug development.
  • Resistance: Strains of TB have developed antibiotic resistance.
  • Distribution Issues: Inconsistent cure distribution; TB is almost extinct in the US and Europe but prevalent in Africa, South America, and Asia.
  • Six countries (India, China, Indonesia, Philippines, Pakistan, Nigeria) account for two-thirds of TB cases.

New Developments

  • Since 2012, new drugs and better vaccines have been developed.
  • Quick tests for TB have been created by companies that made COVID-19 tests.

Call to Action

  • Knowledge and awareness are crucial to combating TB.
  • Partners in Health: Organization working on fighting TB through clinical trials and care delivery.
  • Link to more information and to the Crash Course Lecture on TB provided.

Conclusion

  • TB has been with humanity for millions of years but can be eradicated.
  • Continued awareness, research, and proper medication distribution are key to ending TB.