Calvin's Things to Avoid: Not Wearing Enough Insect Repellent

Let me introduce you to the Filarial Worm (Wuchereria bancrofti). These worms are tiny, round, thread-like parasites that travel from human to human via the mosquito, the buzzing, flitting insect angel of death and pestilence.
In a fascinating example of parasite ingenuity, filarial worm embryos living underneath the skin can sense the onset of nighttime, which is their cue to head upward to the skin's surface in order to increase their chances of being sucked up by a passing mosquito. When they get sucked up, they grow into larvae within the mosquito's body and then get themselves injected into new hosts.
While they feed, these greedy little worms then block the body's lymphatic system—a network of channels, lymph nodes, and glands that helps maintain proper fluid levels in the body by draining lymph from tissues into the bloodstream. This blockage causes fluids to collect in the tissues, which can lead to great swelling, called "lymphedema." Body parts, including your genitals, can swell so enormously that they resemble an elephant's foreleg in size, texture, and color. This is the severely disfiguring and disabling condition of elephantiasis, which according to the Pacific Program to Eliminate Lymphatic Filariasis, is the second-leading cause of permanent and long-term disability in the world. (Oh, by the way, “mental illness” is No. 1.)
Beware! Elephantiasis seems to be spreading! It is estimated that 120 million people in the world have lymphatic filariasis. And more and more cases are being reported every year. Pull out your bug spray, and apply generously.