Causes

• Weakened immune system

  • Great Famine (1315-1317)

    • Torrential rain

    • Harsh winters

    • Ate work animals and seed to survive

    • No crops could grow on wet soil

• Human waste in water streams

  • In streets

• Crowded environments

• Bubonic plague

  • Fleas → lived on rats

  • ↑ lived on other animals

  • Rats bit humans

• Pneumonic plague

  • Air-borne

  • Spread through sneezes, coughs

  • Spread more quickly

• As infected people traveled, disease spread

Consequences (effects on GERMS)