Listen to the creepy frog puppet & you too will avoid intestinal worms. Why did I post this? Because I care about you. Yeah, you're welcome. Previously.
Lymphatic filariasis (or, more dramatically, "elephantiasis") is spread by mosquitoes. The mosquitoes transmit worms to your blood, the worms mate while you sleep, and their progeny travel to your lymph nodes to live a happy life. Unfortunately for you, the worms can get too big, allowing fluid to collect in your limbs or scrotum. Lucky for your neighbors, the disease can be controlled using salt. (China already did it).
Ascaris lumbricoides. According to estimates, about 1.5 billion people--about a quarter of the earth's population--are hosts to the Ascaris lumbricoides parasitic worm. Ascaris worms can grow to be 18 inches in length, and use their host's windpipe and esophagus to migrate between the small intestine and the lungs. A single human host may support dozen of large worms, which can be contracted by contact with fecal matter, animals, or undercooked pork. Under some circumstances (the worms dislike anesthesia, for example) one or more worms may exit from the mouth (a horrifying image), or the anus (one of the most disgusting images I have ever seen, and not safe for work, obviously). Here, the removal of a worm is caught on video (Realplayer). Too disgusting to post? Almost. But 1.5 billion people have got these in their bodies right now. That's what's grosser than gross.
A worm that builds a home inside the human body, lives there happily until breeding time, then begins a journey to emerge from the skin and find a body of water to lay its eggs in. Although this may very well be a pleasant journey for the worm, for the human, it's an excrutiating one. And so we begin The Tale of the Guinea Worm.