Life Cycle of Dracunculus medinensis

1a and 1b. People become infected by drinking unfiltered water containing tiny crustaceans (copepods) that are infected with larvae of Dracunculus or by eating undercooked fish or frogs harboring the larvae.

2. After the copepods are swallowed, they die and release the larvae, which penetrate the wall of the stomach and intestine and enter the abdominal cavity. There, larvae mature into adult worms, which then mate.

3. After mating, the male worms die, and the pregnant females move through tissues under the skin usually to the lower legs or feet. About a year after people are infected, the pregnant female worm comes to the surface of the skin, creating a blister. The blister causes severe, burning discomfort and eventually breaks open.

4. When people attempt to relieve the burning by soaking their leg or foot in water, the pregnant worm releases larvae into the water.

5. The larvae are ingested by another copepod.

6. Inside the copepod, the larvae change into different forms and become able to cause infection. When people swallow the copepods, the cycle is completed.