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Dracunculiasis is infection with Dracunculus medinensis. Symptoms are a painful, inflamed skin lesion, which contains an adult worm, and debilitating arthritis. Diagnosis is by inspection. Treatment is slow removal of the adult worm.
Twenty years ago, dracunculiasis was endemic in much of tropical Africa, Yemen, India, and Pakistan. Today, because of international efforts to interrupt transmission, infection occurs mainly within a narrow belt of African countries and Yemen.
Pathophysiology
Humans become infected by drinking water containing infected microcrustaceans (copepods). The larvae are released, penetrate the bowel wall, and mature in the abdominal cavity into adult worms in about 1 yr. After mating, the male dies, and the gravid female migrates through subcutaneous tissues, usually to the distal lower extremities. The cephalic end of the worm produces an indurated papule that vesiculates and eventually ulcerates. On contact with water, a loop of the worm's uterus prolapses through the skin and discharges motile larvae. Worms that do not reach the skin die and disintegrate or become calcified. Larvae are ingested by copepods.
In most endemic areas, transmission is seasonal and each infectious episode lasts about 1 yr.
Symptoms and Signs
Infection is initially asymptomatic; symptoms usually develop when the worm erupts. Local symptoms include intense itching and a burning pain at the site of the skin lesion. Urticaria, erythema, dyspnea, vomiting, and pruritus are thought to reflect allergic reactions to worm antigens. If the worm is broken during expulsion or extraction, a severe inflammatory reaction ensues with disabling pain. Symptoms subside and the ulcer heals once the adult worm is expelled. In about 50% of cases, secondary bacterial infections occur along the track of the emerging worm. Chronic sequelae include fibrous ankylosis of joints and contraction of tendons.
Diagnosis
Diagnosis is obvious once the white, filamentous adult worm appears at the cutaneous ulcer. Calcified worms can be localized with x-ray examination; they have been found in Egyptian mummies. Serodiagnostic tests are not specific.
Treatment
Treatment consists of slow removal of the adult worm over days to weeks by rolling it on a stick. Surgical removal under local anesthesia is an option but is seldom available in endemic areas. There are no effective drugs for this disease; the beneficial effect of metronidazole (250 mg tid for 10 days) has been ascribed to the drug's anti-inflammatory and antibacterial properties rather than to anthelmintic effects.
Prevention
Filtering drinking water through a piece of cheesecloth, chlorination, or boiling effectively protects against dracunculiasis.
Last full review/revision December 2009 by Richard D. Pearson, MD
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