Carl Zimmer

“In 1494, King Charles VIII of France invaded Italy. Within months, his army collapsed and fled. It was routed not by the Italian army but by a microbe. A mysterious new disease spread through sex killed many of Charles’s soldiers and left survivors weak and disfigured. French soldiers spread the disease across much of Europe, and then it moved into Africa and Asia. Many called it the French disease. The French called it the Italian disease. Arabs called it the Christian disease. Today, it is called syphilis.”
― Carl Zimmer

“Some ancient eukaryote swallowed a photosynthesizing bacteria and became a sunlight gathering alga. Millions of years later one of these algae was devoured by a second eukaryote. This new host gutted the alga, casting away its nucleus and its mitochondria, keeping only the chloroplast. That thief of a thief was the ancestor or Plasmodium and Toxoplasma. And this Russian-doll sequence of events explains why you can cure malaria with an antibiotic that kills bacteria: because Plasmodium has a former bacterium inside it doing some vital business.”
― Carl Zimmer, Parasite Rex: Inside the Bizarre World of Nature's Most Dangerous Creatures