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Blood (Intracellular) and Other Tissue Protozoa 109

vomiting. The symptoms are moderate at the time the and enter the abdominal and retroperitoneal (kidney
adult worm penetrates the skin and the blister bursts. cavities). After copulation, the male dies and the gravid
(pregnant) female approaches the surface of the skin of
Life Cycle an infected individual where a blister forms, then ul-
cerates and exposes the worm. This process takes ap-
The life cycle for D. medinensis is quite simple in com- proximately a year to complete. Upon contact with fresh
parison with some other parasitic organisms. Ingestion water, the female worm emerges upon which her uterus
of unfiltered water containing the infected copecod of prolapses (dropping down of an internal organ) and ex-
the genus Cyclops, a tiny water flea which harbors the in- tremely large numbers of first-stage larvae are released
fective larvae of D. medinensis, begins the reproductive into the surrounding water. These larvae are fed upon by
cycle. These crustaceans are the intermediate host for a particular species of Cyclops, the intermediate host, and
the causative organism for the disease of dracunculiasis. in about a week or slightly longer, the larvae are infective
After ingestion of the copecods, these hosts die and re- for humans who may ingest dirty water containing the
lease the larvae which penetrate the digestive organs infected Cyclops crustaceans (Figure 4-23).

Source: Centers for Disease Control and Prevention (CDC)

FIGURE 4-23 Life cycle of D. medinensis