Dracunculus 
Dracunculus medinensis is often grouped with the filariae, but 
since the life cycle differs significantly it is discussed separately. 
The diagnostic and infective stages, however, are drawn in proportion 
to those of the filariae. The sizes of the adult Dracunculus worms are 
relative to each other but not to filariae adults. 
D. medinensis , or the guinea worm, is probably the “fiery serpent” 
referred to in biblical writings and is a parasite of man in Africa, 
southwestern Asia, northeastern South America and West Indies. 
Man acquires infections with Dracunculus by ingestion of the 
arthropod host containing infective larvae, rather than by bite of the 
vector as is true of most of the other blood parasites. After slowly 
maturing in the loose connective tissue or serous cavities, the 
gravid female migrates to the superficial cutaneous tissue. First 
stage larvae are liberated from the female worm directly into the 
external environment, in this case into water, through an ulcer or 
blister which forms on the skin over the worm’s vaginal opening. 
The free-swimming larvae are ingested by a species of Cyclops and 
mature in the body cavity in about three weeks. 
In many respects, Dracunculus differs from other blood and tissue 
parasites. While it requires an intermediate host for completion of its 
life cycle like the filariae, its choice of host (a crustacean rather 
than a species of Diptera ), mode of entry into both arthropod and 
human (by ingestion), and the existence of free-swimming larvae are 
markedly different from the patterns of other blood and tissue 
parasites. 
Man is not the only definitive host of Dracunculus . Both domestic 
and wild animals — dogs, cats* foxes, mink, even horses and cattle — 
have been reported infected. 
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