A 2-year-old girl experiences severe pain, trouble breathing, and vomiting from a bark scorpion sting; a neuroscientist experiences multi-organ failure and nearly dies from a leptospirosis infection that he caught while swimming in Hawaii; a 20-year-old woman suffers from severe vomiting, extreme headaches, twitching and a strange crawling sensation in her head that turns out to be caused by Balamuthia mandrillaris and dies from it.