Inside the definitive host, the L3 larvae leave the digestive tract and migrate to deeper tissues, where within 60–70 days they undergo their final two molts to form sexually mature adults.

[1] Following the release of her larvae, the female worm dies, and is either extracted by the affected animal, or falls back into the tissue and is calcified.

[1] Adults of both sexes are narrow yellow-white colored worms, with a rounded front-end, and a conical tail-end with a pointed tip.

[1] Adult female Dracunculus worms are noted for their extraordinary length, with some growing up to 100 centimeters long.

[1] These are spread across the globe, with D. ophidensis in the United States, D. brasiliensis in Brazil, D. coluberensis and D. alii in India, D. houdemeri in Vietnam, D. doi in Madagascar, D. dahomensis in Benin, D. oesophageus in Italy, and D. mulbus in Australia and Papua New Guinea.

The only species known to infect a non-snake reptile is D. globocephalus which has been described in snapping turtles in the United States and Costa Rica.

[1] The major exception is D. medinensis, also known as Guinea Worm Disease, as it is by far the most studied Dracunculus as it infects humans.

[2][3] D. medinensis was historically widespread in sub-saharan Africa and South Asia,[1] but is now limited to dozens of cases annually in humans and domestic dogs, and may soon be driven to extinction due to eradication efforts.

It was described in 2009 based on a single female worm from an anaconda in Brazil, and has since also been found in a Brazilian brown-banded water snake.

[1] Case numbers have similarly fallen, from an estimated 3.5 million per year at the 1986 start of the eradication program, to just 15 in 2021.