Causative agent of dracunculosis (Medina or Guinea worm infection)
Male Dracunculus medinensis worms are 1-4cm long, the females measure 50-100cm in body length. Humans contract the disease by ingesting drinking water contaminated with intermediate hosts ("water fleas": fresh water crustacea, Cyclops) containing infective Dracunculus larvae. From the intestine the parasites migrate through the body, females and males mate in the connective tissue, and after approximately 10-12 months p.i. mature females eventually move to the surface of the skin of the legs and feet in 90% of the cases. There, the female provokes an edema, a blister, and then an ulcer. Skin perforation is accompanied by pain, fever, and nausea; secondary bacterial infections occur in approx. 30% of cases. When the wound contacts water, the female extends the anterior end out of it and releases numerous larvae. The larvae are ingested by intermediate hosts and develop into infective stages.
Diagnosis is usually based on the clinical manifestations.
The WHO has been running a control program since the early 1980s based mainly on education of the population and filtration of drinking water using simple cloth or nylon filters. Annual infection incidences have been reduced from three and a half million cases in 1986 to about 75 000 in 2000 (WHO, 2004). Dracunculosis now still occurs in 14 sub-Saharan African countries, but has been officially declared eliminated in some formerly endemic countries (including India, Pakistan, and some African countries). Approximately 73% of all cases are currently reported from Sudan.
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