Guinea Worm

Dracunculus medinensis or Guinea worm is a nematode that causes dracunculiasis, also known as guinea worm disease. The disease is caused by the female which, at up to 800 mm (31 in) in length, is among the longest nematodes infecting humans. In contrast, the longest recorded male Guinea worm is only 40 mm (1.6 in).
The common name "guinea worm" is derived from the Guinea region of Western Africa.
== Description ==
D. medinensis larvae are found in fresh water, where they are ingested by copepods of the genus Cyclops. Within the copepod, the D. medinensis larvae develop to an infective stage within 14 days. When the infected copepod is ingested by a mammalian host, the copepod is dissolved by stomach acid and the D. medinensis larvae migrate through the wall of the mammalian intestine, and mature into adults. One hundred days after infection, a male and female D. medinensis meet and sexually reproduce within the host tissue. The male dies in the host tissue while the female migrates to the host's subcutaneous tissue. Approximately one year after infection, the female causes the formation of a blister on the skin's surface, generally on the lower extremities, though occasionally on the hand or scrotum. When the blister ruptures, the female slowly emerges over the course of several days or weeks. This causes extreme pain and irritation to the host. When the host submerges the affected body part in water, the female expels thousands of larvae into the water. From here, the larvae infect copepods, continuing the life cycle.
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