The disease caused by infection with this parasite is usually termed dracontiasis and the parasite Dracunculus medinensis or the Guinea worm.
The geographical distribution includes India, Arabia, the West Coast of Africa and Brazil.
Life History.—The male has not surely been seen in man so that the pathological condition is entirely connected with the female worm. Almost invariably the female worm, which measures about two feet long by 1/12 inch broad, tends to wander down to the connective tissue structures of the lower extremity. In about 10% of the cases the worm may present elsewhere, as scrotum, back or arms. At the posterior extremity there is a sort of anchoring hook.
With the anterior extremity the worm presses against the overlying skin and causes the formation of a blister-like lesion.
This vesicle later on bursts and, if water is applied to the spot, a delicate tube, the uterus, is extruded and there exude a few drops of a milky fluid, which swarms with the sharp-tailed, striated, sheathless embryos. It is thought that the pouring forth of embryos, when water touches the part, is in order that the embryos may reach the water of a pool through which the infected native may be wading. Once in the water of such a pool, the larvae are swallowed by Cyclops and gaining the body cavity of this little crustacean, they continue to develop for about one month.
During this period there are two ecdyses, the first after about two weeks, when the tail becomes blunt.
When one takes these infected cyclops into the stomach, by drinking water containing them, the cyclops is killed by the gastric juice and the Guinea worm larva breaks out of the dead intermediary host and bores its way through the stomach wall and possibly goes to the tissues about the retroperitoneal region. As a matter of fact we are in ignorance of the exact cycle which goes on, until the fertilized female, with her embryo-distended uterine tube, reaches the lower extremity. A cross section of the female shows the body of the worm to be almost entirely made up of uterus, with an insignificant alimentary canal pressed to one side.
The period of incubation is from 8 to 12 months.
Usually there are no other symptoms than discomfort from the blister and a feeling of heaviness about the affected extremity. At times there may be pain and fever. The parasite may fail to gain exit to the skin surface or die before reaching maturity. In such cases she may become calcified or give rise to abscess formation. The x-ray plate may show a convoluted cord-like structure with frequent breaks in the line.
