Dracunculus nematodes are some of the longest nematode species to infect humans. Females of the genus sometimes grow to nearly a meter in length. Female worms extracted from patients in Pakistan were measured to be between 50 and 80 cm long and approximately 1 to 2 mm wide. (Muller, 1971) Male worms are rarely found, but in two separate cases, their lengths were found to be around 20 and 40 mm long. The mouth of the female worm is a triangular opening surrounded by a plate as well as 4 internal and 4 external papillae. Immature females may have separate internal papillae, while mature worms will have the papillae doubled as pairs. The female worms have a double uterus, with an anterior and posterior branch. The uterus has been described as often containing so many embryos that the worm’s gut is compressed against the body wall and is therefore non-functional. (Muller, 1971) The average number of embryos released by a female was found by Muller to be over 500,000 the first time they were exposed to water, while re-exposure to water in later days resulted in a release of fewer embryos. Larval worms have a striated cuticle as well as lateral ridges. The mouth papillae of the larvae are arranged in the same way as the adult worms, except that there are wider spaces between the internal papillae. Amphids are found near the internal papillae of the worm’s mouth. Male and larval worms are described as having phasmid structures with possible secretory functions as well as associated cilia which may be chemoreceptors. (Muller, 1971)
Works cited:
Muller, R. 1971. Dracunculus and Dracunculiasis. In: Dawes,
B. editor. Advances in Parasitology, volume 9. London. Academic Press Inc. 73-140.
Wow these things are huge! I would imagine they could really do some damage to a host. Is it possible that since the males have similar characteristcs to the larvae and are much smaller than females, that males later develop into females?
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