April 15 - Enterobius vermicularis

Got kids? Then, perhaps you also have Enterobius vermicularis, pinworms. These are oxyurid nematodes and one of the most prevalent diseases of children in the developed world - and the most common nematode infection in the U.S. Adult worms mate in the small intestine, after which the males promptly die and pass out of the host's bodies. Females then settle down in the large intestine and begin to fill their bodies with large numbers of eggs - more than 15,000 of them. She's not content to just pop out those eggs - no, she actually takes an active role in the process. She emerges from the anus and then does one of three things - she either expels them herself, or sometimes she just dies and her body dissolves, or sometimes, the host helps when they itch and kill her and break her open and release the eggs. Then the real fun begins - because those 15,000 eggs are sticky and can go everywhere, especially when little hands touch their bums and then touch, well, everything! Infection occurs when the eggs are ingested. The eggs are very resistant and can even be found in dust that can become airborne and inhaled, to be swallowed later. The photo is of a piece of Scotch tape with eggs attached - this is a common means of diagnosis. The tape is placed over the child's anus over the course of several mornings and then examined for the eggs under a microscope.