While many of us harbor secret fears of vicious or venomous animals, most are unaware that some of the deadliest creatures on Earth live right on and even inside us: microscopic parasites. Take a fascinating tour of a hidden, miniature world that will make your skin crawl.

Under the microscope, parasitic life forms resemble something out of a horror movie, but not all are deadly. Learn about the minute, harmless insects that live in our hair, under our skin and even on our eyelashes. Meet the microscopic, one-celled protozoa that live within our blood cells, causing diseases like malaria and killing millions of people annually. Perhaps most fascinating about these invaders are their incredible life cycles and survival strategies. They can adapt faster than we can attack and have shown a remarkable immunity to treatment, often turning our body's best defenses against us.