But under the microscope, she observed something entirely different. E. histolytica was taking bites out of human cells. Looking through the microscope, “ You could see little parts of the human ...

The single-celled parasite Entamoeba histolytica infects 50 million people each year, killing nearly 70,000. Usually, this wily, shape-shifting amoeba causes nothing worse than diarrhea.

Back then, people believed that it killed cells by injecting them with a poison. But as she watched it through a microscope, she saw something very different. E. histolytica was actually taking bites ...