The weird and wonderful life of Dracunculus medinensis

Unlike many other parasites which are spread through directly contaminated food and water or transmitted by biting insects, Dracunculus medinensis has an intriguing life cycle involving harmless copepods and worms bursting from the skin. The nematode starts it's life as a free-floating egg in a body of water, usually a pond or a slow moving river. The egg eventually hatches and the larvae is ingested by copepods of the Cyclops genus as they comb the water for food. Once inside the unsuspecting crustacean, the larvae will mature into it's infective stage within approximately 14 days. The larvae will live inside the copepod until a human host comes along. If the person is gathering drinking water and they happen to scoop up some infected copepods, they can easily become infected if the water is not treated beforehand. When ingested, the infected copepod will be broken down by the digestive system, allowing the nematode larvae to escape into the intestines of the human (Potter). There it will penetrate the intestinal lining and migrate to subcutaneous tissue by traveling through the lymphatic system. The worm will slowly mature within the host until they reach their adult stage within a year (Hopkins 1981). Assuming both male and female worms are present within the host, the worms will mate once reaching adult stage. The males then die and are broken down by the body. The females, however, will make their way into extremities, often the legs, and move closer to the skin.. There they will create an pustule on the skin, which will eventually burst into a small ulcer, often with the female worm's head at the center. There the worm will wait until the host comes in contact with water. When the when the infected human exposes their affected limb to water, such as by walking into a pond for drinking water collection, the female worm will release its eggs (Manson, 1895). The worm usually creates a severe burning sensation when forming the pustule on the skin, and the host is likely to scratch at it and put the limb in water to help with the pain. This often allows the worm quicker access to water. After the eggs are released, they will hatch and once again be ingested by copepods.


Works Cited

Hopkins, D. R., Foege, W. H. 1981. Guinea Worm Disease. Science, Vol. 212, No. 4494. 495.

Manson, P. 1895. On The Guinea-Worm. The British Medical Journal, Vol. 2, No. 1822. 1350-1351

Potter, M. 1995 (Revised 2012.). Dracunculus medinensis (On line), Filarial Genome Network. Accessed October 12, 2012 at http://plpnemweb.ucdavis.edu/nemaplex/taxadata/Dmedinensis.HTM