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(Guinea Worm Disease; Fiery Serpent)
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.
About 25 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. The Carter Center reports that there were only 542 cases in 2012; all were in 4 African countries—South Sudan, Chad, Mali, and Ethiopia.
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 (eg, when a person attempts to relieve the severe discomfort by immersing the affected limb), 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.
Infection is typically asymptomatic for the first year. Symptoms typically develop when the worm erupts through the skin. 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, causing 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.
The chronic stage of infection is associated with inflammation and pain in the joints and other signs of arthritis. Sequelae include fibrous ankylosis of joints and contraction of tendons.
Treatment consists of slow removal of the adult worm (which may be up to 80 cm long) 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 anthelmintic drugs for this disease; the beneficial effect of metronidazole (250 mg po tid for 10 days) has been ascribed to the drug’s anti-inflammatory and antibacterial properties.
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