Dracunculus Medinensis

Dracunculus Medinensis

Morphology

Dracunculus Medinensis long and thin, they are often confused with filarial worms. Adult female worms measure 70 - 120 cm long by only 2mm in diameter. The male worm is rarely seen but measures a mere 2 cm long by 0.4 mm in diameter. The gravid female, filled with uteri containing rhabditform larvae.

Life Cycle

Human infection is initiated through the ingestion of water contaminated with infected copepods, genus cyclops. These tiny crustaceans, also known as water fleas, harbor the infective third stage larvae of Dracunculus Medinensis. Upon release, the larvae migrate through the duodenum wall, develop, mate, and mature in the loose connective tissue. The intire process takes about a year. As the female approaches the skin, a papule forms, then develops into a blister, and ultimately ulcerates, exposing the worm. Upon contact with fresh water, a portion of the worm`s uterus prolapses and large numbers of first stage larvae are discharged into the water. The life cycle continues as these larvae are ingested by the appropriate species of cyclops, which serve as the intermediate host. Within the copepod, the larvae take about 8 days to become infective for humans.

cyclops

Transmission & Pathogenesis

Following the ingestion of the infected copepod, few or no clinical symptoms occur until just before the blister forms. The gravid female worms`s migration to the skin may provoke localized redness and pain. As the blister forms, there is an onset of fever and generalized allergic symptoms, including: uticaria, intense itching, asthma attacks, periorbital edema, nausea and vomiting. There is a relief of symptoms when the blister ruptures, releasing larvae and worm metabolites into the fluid environment. A portion of the worm will continue to protrude from the wound until larval release is complete. Worms are gradually extracted by winding on a stick, and the ulcer usually heals over in a matter of a few weeks or months. If, however, the worm is damaged or broken during removal, secondary infection, cellulitis, inflamation or abscess formation may result. Occasionally, the adult worm does not erupt through the skin and becomes encapsulated and calcified in the subcutaneous tissue.

blister forms

Laboratory Diagnosis

Diagnosis of dracunculiasis is typically based on clinical manifestations. X-rays may be used to locate dead calcified worms in subcutaneous tissues.

dracunculiasis

Treatment & Prevention

Method to remove adult worm is slowly wind the worm around a stick at rate of few centimetres per day carefully to ensure patient not expose to secondary infection (if worm is broken). 

Prevention depends on the provision of properly treated, safe, drinking water (boiled water).