[5] The length of specimens exhibits extreme sexual dimorphism, as the longest recorded male Guinea worm is only 4 cm (1+1⁄2 in).

Dracunculus medinensis ("little dragon from Medina") was described in Egypt as early as the 15th century BCE and possibly was the "fiery serpent" afflicting the Israelites described in the Bible.

This led Russian naturalist Alexei Pavlovich Fedchenko to discover in 1870 that D. medinensis is similarly transmitted via copepod intermediate hosts.

After maturing and mating within the host, the males die and females (length 70–120 cm or 28–47 in) migrate in subcutaneous tissue towards the skin's surface.

Around a year after the infection, the female causes the formation of a blister on the skin's surface, generally on the lower extremities, though occasionally on the hand or scrotum.

[12] The parasite relies on people accidentally consuming microcrustaceans of the genus Cyclops (copepods), that dwell in stationary bodies of water such as ponds, large, open wells (with stairs), or rain-filled cisterns.

[13] As it emerges to the subcutaneous tissue, the female releases a toxic chemical that may result in nausea, rash at site, diarrhea, dizziness, localized edema, reddish papule, blister, and itching.

[13] Arthritis or paraplegia can result from a worm that fails to reach the skin and gets calcified in or along the joint or finds its way into the central nervous tissue.

[13] Aseptic abscesses and cystic swelling can also occur when worms rupture before emerging, causing an acute inflammatory response from the host's immune system.

After each day's worth of extraction, the exposed portion of the worm is wrapped around a piece of rolled-up gauze or small stick to maintain tension.

Once secure, topical antibiotics are applied to the affected region, to help prevent secondary infections due to bacteria, which is then wrapped in gauze to protect the wound.