White bloods cells, known scientifically as leukocytes, are immune system cells that fight infect. The immune system is made up of a network of cells, tissues, and organs that work together to protect the body. Sometimes our bodies encounter pathogens like bacteria, or in this case a parasitic worm. Roundworms, or nematodes, are parasites that can infect people by living and feeding in the intestines. There are different kinds of worms that can cause infection, and they can range in length from 1 millimeter to 1 meter. Luckily, this worm was no challenge for these hungry white blood cells. ...