Dracunculus insignis

Taxonomy: Order Spirurida, Superfamily Dracunculoidea

Spirurids of veterinary importance include stomach dwelling nematodes (i.e. Physaloptera, Spirocerca, Habronema, and Draschia) as well as members of the Superfamily Filarioidea (i.e. Stephanofilaria, Dirofilaria, Onchocerca, and Setaria).  All undergo indirect life cycles using arthropod intermediate hosts.  Dracunculus insignis is a spirurid nematode of mustelids (mink, raccoon, otter) that is very rarely diagnosed in dogs in North America.  Adult nematodes live in 3-5 cm swellings in the subcutaneous tissues (often of the limbs).  On contact with water, adult females emerge from blisters on the skin and release first stage larvae.  The larvae are ingested by an aquatic crustacean (copepod), and develop to third stage larvae (L3) at a temperature dependent rate.  Definitive hosts (including dogs) are infected by ingesting L3 in a copepod intermediate host or in a frog or fish paratenic host.  Dogs infected with the parasite can be treated by placing the affected limb in water, encouraging the adult female to emerge, and/or by dissection and removal of adult worms.  Dracunculus insignis is not zoonotic, but a relative, Dracunculus medinensis (the Guinea worm), found in Africa and the Middle East, is the cause of dracunculiasis in people.