Microscopic Monsters (S01E07)

What unpleasant intruders lurk in our homes and on our bodies? Fleas, parasites, worms, and all sorts of tiny, revolting creatures. Mark is constantly scratching, but the source of his discomfort remains a mystery. The Shrinking Scientists spring into action to uncover the truth. They are joined in the studio by microscope specialist Robert Hooke, who lends his expertise to the investigation.